Table of Contents


UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
     
FORM 10-Q
     
☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
For the quarterly period ended September 30, 2017March 31, 2018
 
or
 
☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
For the transition period from                    to                    

alliantenergylogo0331201810q.jpg
Commission
File Number
 
Name of Registrant, State of Incorporation,
Address of Principal Executive Offices and Telephone Number
 
IRS Employer
Identification Number
1-9894 ALLIANT ENERGY CORPORATION 39-1380265
  (a Wisconsin corporation)  
  4902 N. Biltmore Lane  
  Madison, Wisconsin 53718  
  Telephone (608) 458-3311  
   
1-4117 INTERSTATE POWER AND LIGHT COMPANY 42-0331370
  (an Iowa corporation)  
  Alliant Energy Tower  
  Cedar Rapids, Iowa 52401  
  Telephone (319) 786-4411  
   
0-337 WISCONSIN POWER AND LIGHT COMPANY 39-0714890
  (a Wisconsin corporation)  
  4902 N. Biltmore Lane  
  Madison, Wisconsin 53718  
  Telephone (608) 458-3311  
This combined Form 10-Q is separately filed by Alliant Energy Corporation, Interstate Power and Light Company and Wisconsin Power and Light Company. Information contained in the Form 10-Q relating to Interstate Power and Light Company and Wisconsin Power and Light Company is filed by each such registrant on its own behalf. Each of Interstate Power and Light Company and Wisconsin Power and Light Company makes no representation as to information relating to registrants other than itself.
Indicate by check mark whether the registrants (1) have filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrants were required to file such reports), and (2) have been subject to such filing requirements for the past 90 days.    Yes ☒  No ☐
Indicate by check mark whether the registrants have submitted electronically and posted on their corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrants were required to submit and post such files).    Yes ☒  No ☐
Indicate by check mark whether the registrants are large accelerated filers, accelerated filers, non-accelerated filers, smaller reporting companies, or emerging growth companies. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.
 Large Accelerated Filer  Accelerated Filer  Non-accelerated Filer  Smaller Reporting Company Emerging Growth Company
Alliant Energy Corporation☒           
Interstate Power and Light Company      ☒     
Wisconsin Power and Light Company      ☒     
If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐
Indicate by check mark whether the registrants are shell companies (as defined in Rule 12b-2 of the Exchange Act).    Yes ☐  No ☒
Number of shares outstanding of each class of common stock as of September 30, 2017March 31, 2018:
Alliant Energy CorporationCommon stock, $0.01 par value, 231,204,360231,481,828 shares outstanding
  
Interstate Power and Light CompanyCommon stock, $2.50 par value, 13,370,788 shares outstanding (all of which are owned beneficially and of record by Alliant Energy Corporation)
  
Wisconsin Power and Light CompanyCommon stock, $5 par value, 13,236,601 shares outstanding (all of which are owned beneficially and of record by Alliant Energy Corporation)



Table of Contents


TABLE OF CONTENTS
 Page
Definitions
1
Forward-looking Statements
1
Part I. Financial Information
3
Item 1. Condensed Consolidated Financial Statements (Unaudited)
3
Alliant Energy Corporation
3
Interstate Power and Light Company
6
Wisconsin Power and Light Company
9
Combined Notes to Condensed Consolidated Financial Statements
12
1. Summary of Significant Accounting Policies
12
2. Regulatory Matters
1314
3. Property, Plant and Equipment
15
4. Receivables
1615
5. Investments
1716
6. Common Equity
1716
7. Debt
1816
8. Revenues
17
9. Income Taxes
1918
9.10. Benefit Plans
19
10.11. Fair Value Measurements
21
11.12. Derivative Instruments
2422
12.13. Commitments and Contingencies
2423
13.14. Segments of Business
2725
14.15. Related Parties
2826
Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations
2927
Item 3. Quantitative and Qualitative Disclosures About Market Risk
4234
Item 4. Controls and Procedures
4234
Part II. Other Information
4235
Item 1A. Risk Factors
4235
Item 2. Unregistered Sales of Equity Securities and Use of Proceeds
4335
Item 6. Exhibits
4335
Signatures
4436


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DEFINITIONS
The following abbreviations or acronyms used in this Form 10-Q are defined below:
Abbreviation or AcronymDefinitionAbbreviation or AcronymDefinition
20162017 Form 10-KCombined Annual Report on Form 10-K filed by Alliant Energy, IPL and WPL for the year ended Dec. 31, 20162017ITCIUBITC Midwest LLCIowa Utilities Board
AEFAlliant Energy Finance, LLCIUBIowa Utilities Board
AFUDCAllowance for funds used during constructionMarshalltownMarshalltown Generating Station
Alliant EnergyAlliant Energy CorporationMDAManagement’s Discussion and Analysis of Financial Condition and Results of Operations
ATCAFUDCAmerican Transmission CompanyAllowance for funds used during constructionMISOMidcontinent Independent System Operator, Inc.
ATIAlliant EnergyAE Transco Investments, LLCAlliant Energy CorporationMWMegawatt
CDDATCCooling degree daysAmerican Transmission Company LLCMWhMegawatt-hour
ATC HoldingsInterest in American Transmission Company LLC and ATC Holdco LLCN/ANot applicable
Corporate ServicesAlliant Energy Corporate Services, Inc.N/ANot applicable
DthDekathermNote(s)Combined Notes to Condensed Consolidated Financial Statements
DthDekathermNOxNitrogen oxide
EGUElectric generating unitNOxOPEBNitrogen oxideOther postretirement benefits
EPAU.S. Environmental Protection AgencyOPEBOther postretirement benefits
EPSEarnings per weighted average common sharePSCWPublic Service Commission of Wisconsin
FERCFederal Energy Regulatory CommissionRiversideRiverside Energy Center
Financial StatementsCondensed Consolidated Financial StatementsRMTSCRRMT, Inc.Selective catalytic reduction
FTRFinancial transmission rightSCRTax ReformSelective catalytic reductionTax Cuts and Jobs Act
Fuel-relatedElectric production fuel and purchased powerSO2U.S.Sulfur dioxideUnited States of America
GAAPU.S. generally accepted accounting principlesU.S.United States of America
HDDHeating degree daysWhiting PetroleumWhiting Petroleum Corporation
IPLInterstate Power and Light CompanyWPLWisconsin Power and Light Company

FORWARD-LOOKING STATEMENTS

Statements contained in this report that are not of historical fact are forward-looking statements intended to qualify for the safe harbors from liability established by the Private Securities Litigation Reform Act of 1995. These forward-looking statements can be identified as such because the statements include words such as “may,” “believe,” “expect,” “anticipate,” “plan,” “project,” “will,” “projections,” “estimate,” or other words of similar import. Similarly, statements that describe future financial performance or plans or strategies are forward-looking statements. Such forward-looking statements are subject to certain risks and uncertainties that could cause actual results to differ materially from those expressed in, or implied by, such statements. Some, but not all, of the risks and uncertainties of Alliant Energy, IPL and WPL that could materially affect actual results include:

federal and state regulatory or governmental actions, including the impact of energy, tax (including potential tax reform), financial and health care legislation, and regulatory agency orders;
IPL’s and WPL’s ability to obtain adequate and timely rate relief to allow for, among other things, earning a return on rate base additions and the recovery of costs, including fuel costs, operating costs, transmission costs, environmental compliance and remediation costs, deferred expenditures, deferred tax assets, capital expenditures, and remaining costs related to EGUs that may be permanently closed, earning their authorized rates of return, and the payments to their parent of expected levels of dividends;
the ability to continue cost controlsfederal and operational efficiencies;
state regulatory or governmental actions, including the impact of IPL’s pending retail electric base rate review;
weather effects on results of utility operations;
the impact of the economy in IPL’senergy, tax, financial and WPL’s service territorieshealth care legislation, and the resulting impacts on sales volumes, margins and the ability to collect unpaid bills;regulatory agency orders;
the impact of customer- and third party-owned generation, including alternative electric suppliers, in IPL’s and WPL’s service territories on system reliability, operating expenses and customers’ demand for electricity;
the impact of energy efficiency, franchise retention and customer disconnects on sales volumes and margins;
the impact that price changes may have on IPL’s and WPL’s customers’ demand for electric, gas and steam services and their ability to pay their bills;
developments that adversely impact the ability to implementutilize tax credits and net operating losses generated to date, and those that may be generated in the strategic plan;future, before they expire;
the abilitydirect or indirect effects resulting from terrorist incidents, including physical attacks and cyber attacks, or responses to qualify for the full level of production tax credits on planned new wind farms and such incidents;
the impact of penalties or third-party claims related to, or in connection with, a failure to maintain the security of personally identifiable information, including associated costs to notify affected persons and to mitigate their information security concerns;
employee workforce factors, including changes in key executives, ability to production tax credits for existing wind farms;hire and retain employees with specialized skills, ability to create desired corporate culture, collective bargaining agreements and negotiations, work stoppages or restructurings;
weather effects on results of utility operations;

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issues related to the availability and operations of EGUs, including start-up risks, breakdown or failure of equipment, performance below expected or contracted levels of output or efficiency, operator error, employee safety, transmission constraints, compliance with mandatory reliability standards and risks related to recovery of resulting incremental costs through rates;
disruptions in the supply and delivery of natural gas, purchased electricity and coal;
changes in the price of delivered natural gas, purchased electricity and coal due to shifts in supply and demand caused by market conditions and regulations;
impacts on equity income from unconsolidated investments due to further potential changes to ATC LLC’s authorized return on equity;
issues associated with environmental remediation and environmental compliance, including compliance with the Consent Decree between WPL, the EPA and the Sierra Club, the Consent Decree between IPL, the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa, the Coal Combustion Residuals Rule, the Clean Power Plan, future changes in environmental laws and regulations, including the EPA’s regulations for carbon dioxide emissions reductions from new and existing fossil-fueled EGUs, and litigation associated with environmental requirements;
the ability to defend against environmental claims brought by state and federal agencies, such as the EPA, state natural resources agencies or third parties, such as the Sierra Club, and the impact on operating expenses of defending and resolving such claims;
impacts that storms or natural disasterscontinued access to the capital markets on competitive terms and rates, and the actions of credit rating agencies;
inflation and interest rates;
the impact of the economy in IPL’s and WPL’s service territories may haveand the resulting impacts on their operationssales volumes, margins and recoverythe ability to collect unpaid bills;
changes in the price of costs associateddelivered natural gas, purchased electricity and coal due to shifts in supply and demand caused by market conditions and regulations;
disruptions in the supply and delivery of natural gas, purchased electricity and coal;
changes in the price of transmission services and the ability to recover the cost of transmission services in a timely manner;
developments that adversely impact the ability to implement the strategic plan;
ability to obtain regulatory approval for wind projects with restoration activities;
acceptable conditions, to acquire sufficient transmission-ready wind sites, to complete construction within the direct or indirect effects resulting from terrorist incidents, including physical attacks and cyber attacks, or responses to such incidents;
the impact of penalties or third-party claims related to, or in connection with, a failure to maintain the security of personally identifiable information, including associated costs to notify affected personscost caps set by regulators and to mitigate their information security concerns;meet all requirements to qualify for the full level of production tax credits;
the direct or indirect effects resulting from breakdown or failure of equipment in the operation of electric and gas distribution systems, such as mechanical problems and explosions or fires, and compliance with electric and gas transmission and distribution safety regulations;
issues related to the availability and operations of EGUs, including start-up risks, breakdown or failure of equipment, performance below expected or contracted levels of output or efficiency, operator error, employee safety, transmission constraints, compliance with mandatory reliability standards and risks related to recovery of resulting incremental costs through rates;
impacts that storms or natural disasters in IPL’s and WPL’s service territories may have on their operations and recovery of IPL’s future tax benefits from Iowa rate-making practices, including deductions for repairs expenditures and allocation of mixed service costs and recoverability of the associated regulatory assets from customers, when the differences reverse in future periods;
risks associated with non-regulated renewable investments;restoration activities;
any material post-closing adjustments related to any past asset divestitures, including the sales of IPL’s Minnesota electric and natural gas assets, and Whiting Petroleum, which could result from, among other things, indemnification agreements, warranties, parental guarantees or litigation;
continued accessAlliant Energy’s ability to sustain its dividend payout ratio goal;
changes to costs of providing benefits and related funding requirements of pension and OPEB plans due to the capital marketsmarket value of the assets that fund the plans, economic conditions, financial market performance, interest rates, life expectancies and demographics;
material changes in employee-related benefit and compensation costs;
risks associated with operation and ownership of non-utility holdings;
changes in technology that alter the channels through which customers buy or utilize Alliant Energy’s, IPL’s or WPL’s products and services;
impacts on competitive termsequity income from unconsolidated investments due to further potential changes to ATC’s authorized return on equity;
impacts of IPL’s future tax benefits from Iowa rate-making practices, including deductions for repairs expenditures, allocation of mixed service costs and rates,state depreciation, and recoverability of the actionsassociated regulatory assets from customers, when the differences reverse in future periods;
the impacts of credit rating agencies;
inflationadjustments made to deferred tax assets and interest rates;liabilities from changes in the tax laws;
changes to the creditworthiness of counterparties with which Alliant Energy, IPL and WPL have contractual arrangements, including participants in the energy markets and fuel suppliers and transporters;
current or future litigation, regulatory investigations, proceedings or inquiries;
reputational damage from negative publicity, protests, fines, penalties and other negative consequences resulting in regulatory and/or legal actions;
Alliant Energy’s ability to sustain its dividend payout ratio goal;
employee workforce factors, including changes in key executives, collective bargaining agreements and negotiations, work stoppages or restructurings;
changes in technology that alter the channels through which electric customers buy or utilize electricity;
material changes in employee-related benefit and compensation costs;
the effect of accounting standards issued periodically by standard-setting bodies;
the impact of adjustments made to deferred tax assets and liabilities from state apportionment assumptions;
the ability to utilize tax credits and net operating losses generated to date, and those that may be generated in the future, before they expire;
the ability to successfully complete tax audits and changes in tax accounting methods with no material impact on earnings and cash flows; and
•
factors listed in MDA and Risk Factors in Item 1A in the 20162017 Form 10-K.

Alliant Energy, IPL and WPL each assume no obligation, and disclaim any duty, to update the forward-looking statements in this report, except as required by law.

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PART I. FINANCIAL INFORMATION
ITEM 1. CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
ALLIANT ENERGY CORPORATION
CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)
For the Three Months For the Nine MonthsFor the Three Months
Ended September 30, Ended September 30,Ended March 31,
2017 2016 2017 20162018 2017
(in millions, except per share amounts)(in millions, except per share amounts)
Operating revenues:       
Revenues:   
Electric utility
$840.6
 
$864.3
 
$2,199.1
 
$2,209.1

$708.7
 
$677.6
Gas utility45.8
 39.5
 262.7
 248.7
185.6
 154.3
Other utility11.2
 9.4
 34.4
 35.0
13.2
 11.7
Non-regulated9.3
 11.4
 29.9
 30.2
Total operating revenues906.9
 924.6
 2,526.1
 2,523.0
Non-utility8.8
 10.3
Total revenues916.3
 853.9
Operating expenses:          
Electric production fuel and purchased power222.6
 245.9
 614.7
 646.3
203.2
 207.8
Electric transmission service121.0
 138.6
 363.3
 396.8
126.4
 124.7
Cost of gas sold15.0
 12.5
 135.5
 132.3
111.2
 92.2
Asset valuation charges for Franklin County wind farm—
 86.4
 —
 86.4
Other operation and maintenance169.1
 148.6
 467.1
 438.2
162.4
 148.6
Depreciation and amortization120.7
 104.1
 342.7
 308.7
120.4
 107.0
Taxes other than income taxes27.0
 25.9
 79.1
 77.2
27.0
 26.4
Total operating expenses675.4
 762.0
 2,002.4
 2,085.9
750.6
 706.7
Operating income231.5
 162.6
 523.7
 437.1
165.7
 147.2
Interest expense and other:       
Other (income) and deductions:   
Interest expense53.9
 48.8
 159.0
 144.8
59.2
 52.3
Equity income from unconsolidated investments, net(10.1) (9.2) (32.9) (28.8)(21.3) (11.5)
Allowance for funds used during construction(9.6) (15.8) (36.7) (44.3)(14.9) (17.0)
Interest income and other(0.2) (0.1) (0.4) (0.3)
Total interest expense and other34.0
 23.7
 89.0
 71.4
Other2.4
 4.2
Total other (income) and deductions25.4
 28.0
Income from continuing operations before income taxes197.5
 138.9
 434.7
 365.7
140.3
 119.2
Income taxes26.1
 7.5
 64.9
 47.2
16.8
 17.6
Income from continuing operations, net of tax171.4
 131.4
 369.8
 318.5
123.5
 101.6
Income (loss) from discontinued operations, net of tax—
 (0.4) 1.4
 (2.0)
Income from discontinued operations, net of tax—
 1.4
Net income171.4
 131.0
 371.2
 316.5
123.5
 103.0
Preferred dividend requirements of Interstate Power and Light Company2.6
 2.6
 7.7
 7.7
2.6
 2.6
Net income attributable to Alliant Energy common shareowners
$168.8
 
$128.4
 
$363.5
 
$308.8

$120.9
 
$100.4
Weighted average number of common shares outstanding (basic and diluted)231.0
 227.2
 229.2
 227.0
231.4
 227.6
Earnings per weighted average common share attributable to Alliant Energy common shareowners (basic and diluted):
          
Income from continuing operations, net of tax
$0.73
 
$0.57
 
$1.58
 
$1.37

$0.52
 
$0.43
Income (loss) from discontinued operations, net of tax—
 —
 0.01
 (0.01)
Income from discontinued operations, net of tax—
 0.01
Net income
$0.73
 
$0.57
 
$1.59
 
$1.36

$0.52
 
$0.44
Amounts attributable to Alliant Energy common shareowners:          
Income from continuing operations, net of tax
$168.8
 
$128.8
 
$362.1
 
$310.8

$120.9
 
$99.0
Income (loss) from discontinued operations, net of tax—
 (0.4) 1.4
 (2.0)
Income from discontinued operations, net of tax—
 1.4
Net income
$168.8
 
$128.4
 
$363.5
 
$308.8

$120.9
 
$100.4
Dividends declared per common share
$0.315
 
$0.29375
 
$0.945
 
$0.88125

$0.335
 
$0.315

The accompanying Combined Notes to Condensed Consolidated Financial Statements are an integral part of these statements.

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ALLIANT ENERGY CORPORATION
CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED)
September 30,
2017		 December 31,
2016		March 31,
2018		 December 31,
2017
(in millions, except per
share and share amounts)
(in millions, except per
share and share amounts)
ASSETS      
Current assets:      
Cash and cash equivalents
$9.2
 
$8.2

$19.1
 
$27.9
Accounts receivable, less allowance for doubtful accounts336.1
 493.3
343.2
 482.8
Production fuel, at weighted average cost80.9
 98.1
76.7
 72.3
Gas stored underground, at weighted average cost40.6
 37.6
16.3
 44.5
Materials and supplies, at weighted average cost99.1
 86.6
109.8
 105.6
Regulatory assets84.2
 57.8
74.9
 84.3
Other101.4
 95.5
85.9
 87.7
Total current assets751.5
 877.1
725.9
 905.1
Property, plant and equipment, net10,931.1
 10,279.2
11,439.6
 11,234.5
Investments:      
ATC Investment339.2
 317.6
ATC Holdings275.5
 274.2
Other119.4
 20.0
139.2
 121.9
Total investments458.6
 337.6
414.7
 396.1
Other assets:      
Regulatory assets1,952.3
 1,857.3
1,589.2
 1,582.4
Deferred charges and other21.4
 22.6
72.4
 69.7
Total other assets1,973.7
 1,879.9
1,661.6
 1,652.1
Total assets
$14,114.9
 
$13,373.8

$14,241.8
 
$14,187.8
LIABILITIES AND EQUITY      
Current liabilities:      
Current maturities of long-term debt
$105.2
 
$4.6

$855.7
 
$855.7
Commercial paper390.3
 244.1
336.4
 320.2
Other short-term borrowings95.0
 —
95.0
 95.0
Accounts payable478.1
 445.3
363.1
 477.3
Regulatory liabilities145.1
 186.2
172.2
 140.0
Accrued taxes39.4
 59.5
Other217.0
 222.3
251.1
 260.8
Total current liabilities1,470.1
 1,162.0
2,073.5
 2,149.0
Long-term debt, net (excluding current portion)4,255.1
 4,315.6
4,056.8
 4,010.6
Other liabilities:      
Deferred tax liabilities2,774.7
 2,570.2
1,511.6
 1,478.4
Regulatory liabilities483.4
 494.8
1,365.7
 1,357.2
Pension and other benefit obligations481.3
 489.9
488.9
 504.0
Other296.1
 279.3
313.8
 306.4
Total other liabilities4,035.5
 3,834.2
3,680.0
 3,646.0
Commitments and contingencies (Note 12)


 

Commitments and contingencies (Note 13)


 

Equity:      
Alliant Energy Corporation common equity:      
Common stock - $0.01 par value - 480,000,000 shares authorized; 231,204,360 and 227,673,654 shares outstanding2.3
 2.3
Common stock - $0.01 par value - 480,000,000 shares authorized; 231,481,828 and 231,348,646 shares outstanding2.3
 2.3
Additional paid-in capital1,838.2
 1,693.1
1,851.4
 1,845.5
Retained earnings2,324.8
 2,177.0
2,389.4
 2,346.0
Accumulated other comprehensive loss(0.4) (0.4)(0.5) (0.5)
Shares in deferred compensation trust - 454,532 and 441,695 shares at a weighted average cost of $23.52 and $22.71 per share(10.7) (10.0)
Shares in deferred compensation trust - 458,639 and 463,365 shares at a weighted average cost of $24.17 and $23.91 per share(11.1) (11.1)
Total Alliant Energy Corporation common equity4,154.2
 3,862.0
4,231.5
 4,182.2
Cumulative preferred stock of Interstate Power and Light Company200.0
 200.0
200.0
 200.0
Total equity4,354.2
 4,062.0
4,431.5
 4,382.2
Total liabilities and equity
$14,114.9
 
$13,373.8

$14,241.8
 
$14,187.8

The accompanying Combined Notes to Condensed Consolidated Financial Statements are an integral part of these statements.

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ALLIANT ENERGY CORPORATION
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)
For the Nine MonthsFor the Three Months
Ended September 30,Ended March 31,
2017 20162018 2017
(in millions)(in millions)
Cash flows from operating activities:      
Net income
$371.2
 
$316.5

$123.5
 
$103.0
Adjustments to reconcile net income to net cash flows from operating activities:      
Depreciation and amortization342.7
 308.7
120.4
 107.0
Deferred tax expense and tax credits102.7
 76.7
17.6
 22.7
Asset valuation charges for Franklin County wind farm—
 86.4
Other(7.1) (44.0)(14.8) (7.6)
Other changes in assets and liabilities:      
Accounts receivable72.8
 (101.0)(147.6) (143.2)
Sales of accounts receivable91.0
 (4.0)
Gas stored underground28.2
 25.4
Regulatory assets(108.9) 36.6
(3.4) (40.6)
Derivative assets11.0
 28.1
Accounts payable(59.6) (41.3)
Regulatory liabilities(64.8) (66.5)34.2
 14.2
Deferred income taxes101.0
 71.8
14.9
 32.8
Other(17.2) (27.2)(35.1) 18.5
Net cash flows from operating activities883.4
 654.0
89.3
 119.0
Cash flows used for investing activities:      
Construction and acquisition expenditures:      
Utility business(909.7) (743.6)(335.2) (268.9)
Alliant Energy Corporate Services, Inc. and non-regulated businesses(139.7) (43.3)
Other(20.3) (22.6)
Cash receipts on sold receivables284.3
 214.7
Other(22.9) 15.1
(14.0) (10.4)
Net cash flows used for investing activities(1,072.3) (771.8)(85.2) (87.2)
Cash flows from financing activities:   
Cash flows used for financing activities:   
Common stock dividends(215.7) (199.8)(77.5) (71.5)
Proceeds from issuance of common stock, net143.2
 20.4
Proceeds from issuance of long-term debt—
 300.0
Net change in commercial paper and other short-term borrowings281.2
 78.5
Net change in commercial paper62.1
 58.7
Other(18.8) (2.4)5.6
 (17.1)
Net cash flows from financing activities189.9
 196.7
Net increase in cash and cash equivalents1.0
 78.9
Cash and cash equivalents at beginning of period8.2
 5.8
Cash and cash equivalents at end of period
$9.2
 
$84.7
Net cash flows used for financing activities(9.8) (29.9)
Net increase (decrease) in cash, cash equivalents and restricted cash(5.7) 1.9
Cash, cash equivalents and restricted cash at beginning of period33.9
 13.1
Cash, cash equivalents and restricted cash at end of period
$28.2
 
$15.0
Supplemental cash flows information:      
Cash paid during the period for:      
Interest, net of capitalized interest
($158.5) 
($140.7)
($54.2) 
($51.8)
Income taxes, net
($11.4) 
($8.3)
$—
 
($2.3)
Significant non-cash investing and financing activities:      
Accrued capital expenditures
$197.2
 
$99.9

$144.9
 
$139.3
Beneficial interest obtained in exchange for securitized accounts receivable
$120.9
 
$149.0

The accompanying Combined Notes to Condensed Consolidated Financial Statements are an integral part of these statements.

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Table of Contents


INTERSTATE POWER AND LIGHT COMPANY
CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)
For the Three Months For the Nine MonthsFor the Three Months
Ended September 30, Ended September 30,Ended March 31,
2017 2016 2017 20162018 2017
(in millions)(in millions)
Operating revenues:       
Revenues:   
Electric utility
$489.0
 
$483.2
 
$1,217.6
 
$1,209.2

$405.7
 
$356.2
Gas utility27.4
 23.9
 147.2
 142.6
108.1
 83.1
Steam and other11.0
 9.1
 33.3
 34.1
12.0
 11.2
Total operating revenues527.4
 516.2
 1,398.1
 1,385.9
Total revenues525.8
 450.5
Operating expenses:          
Electric production fuel and purchased power122.5
 125.0
 330.0
 324.8
114.6
 109.5
Electric transmission service78.2
 95.9
 235.0
 270.7
90.8
 81.7
Cost of gas sold9.9
 8.0
 74.6
 76.3
60.6
 47.8
Other operation and maintenance104.4
 94.8
 288.7
 279.8
105.5
 93.2
Depreciation and amortization66.2
 52.7
 181.0
 157.8
64.8
 53.6
Taxes other than income taxes14.4
 13.9
 41.1
 40.6
13.9
 13.4
Total operating expenses395.6
 390.3
 1,150.4
 1,150.0
450.2
 399.2
Operating income131.8
 125.9
 247.7
 235.9
75.6
 51.3
Interest expense and other:       
Other (income) and deductions:   
Interest expense27.9
 25.5
 83.5
 75.4
29.8
 27.7
Allowance for funds used during construction(4.7) (13.8) (25.1) (36.2)(7.4) (14.3)
Interest income and other(0.1) —
 (0.2) (0.1)
Total interest expense and other23.1
 11.7
 58.2
 39.1
Other0.8
 1.8
Total other (income) and deductions23.2
 15.2
Income before income taxes108.7
 114.2
 189.5
 196.8
52.4
 36.1
Income tax benefit(14.3) (2.5) (18.6) (2.5)
Income tax expense (benefit)3.1
 (3.7)
Net income123.0
 116.7
 208.1
 199.3
49.3
 39.8
Preferred dividend requirements2.6
 2.6
 7.7
 7.7
2.6
 2.6
Earnings available for common stock
$120.4
 
$114.1
 
$200.4
 
$191.6

$46.7
 
$37.2
Earnings per share data is not disclosed given Alliant Energy Corporation is the sole shareowner of all shares of IPL’s common stock outstanding during the periods presented.
The accompanying Combined Notes to Condensed Consolidated Financial Statements are an integral part of these statements.

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INTERSTATE POWER AND LIGHT COMPANY
CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED)
September 30,
2017		 December 31,
2016		March 31,
2018		 December 31,
2017
(in millions, except per
share and share amounts)
(in millions, except per
share and share amounts)
ASSETS  
Current assets:      
Cash and cash equivalents
$4.7
 
$3.3

$2.9
 
$3.6
Accounts receivable, less allowance for doubtful accounts143.5
 240.7
145.9
 264.9
Production fuel, at weighted average cost56.7
 70.3
55.0
 52.4
Gas stored underground, at weighted average cost21.6
 16.3
3.6
 20.3
Materials and supplies, at weighted average cost52.6
 46.5
61.6
 60.6
Regulatory assets38.9
 17.7
38.1
 41.9
Other39.3
 27.7
23.2
 32.3
Total current assets357.3
 422.5
330.3
 476.0
Property, plant and equipment, net5,764.9
 5,435.6
6,088.5
 5,926.2
Other assets:      
Regulatory assets1,552.0
 1,441.1
1,192.8
 1,189.7
Deferred charges and other8.5
 5.5
16.2
 14.1
Total other assets1,560.5
 1,446.6
1,209.0
 1,203.8
Total assets
$7,682.7
 
$7,304.7

$7,627.8
 
$7,606.0
LIABILITIES AND EQUITY  
Current liabilities:      
Current maturities of long-term debt
$100.0
 
$—

$350.0
 
$350.0
Commercial paper4.0
 —
Accounts payable224.6
 186.3
183.2
 220.3
Accounts payable to associated companies56.4
 43.3
35.9
 50.1
Regulatory liabilities85.9
 149.6
102.4
 69.7
Accrued taxes39.3
 53.8
Other92.8
 88.8
127.4
 137.6
Total current liabilities603.0
 521.8
798.9
 827.7
Long-term debt, net (excluding current portion)2,095.0
 2,153.5
2,102.2
 2,056.0
Other liabilities:      
Deferred tax liabilities1,643.5
 1,511.8
926.5
 910.7
Regulatory liabilities298.9
 281.2
674.9
 685.7
Pension and other benefit obligations171.4
 173.2
171.6
 173.8
Other238.5
 214.2
239.2
 242.4
Total other liabilities2,352.3
 2,180.4
2,012.2
 2,012.6
Commitments and contingencies (Note 12)


 

Commitments and contingencies (Note 13)


 

Equity:      
Interstate Power and Light Company common equity:      
Common stock - $2.50 par value - 24,000,000 shares authorized; 13,370,788 shares outstanding33.4
 33.4
33.4
 33.4
Additional paid-in capital1,697.8
 1,597.8
1,797.8
 1,797.8
Retained earnings701.2
 617.8
683.3
 678.5
Total Interstate Power and Light Company common equity2,432.4
 2,249.0
2,514.5
 2,509.7
Cumulative preferred stock200.0
 200.0
200.0
 200.0
Total equity2,632.4
 2,449.0
2,714.5
 2,709.7
Total liabilities and equity
$7,682.7
 
$7,304.7

$7,627.8
 
$7,606.0

The accompanying Combined Notes to Condensed Consolidated Financial Statements are an integral part of these statements.

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INTERSTATE POWER AND LIGHT COMPANY
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)
For the Nine MonthsFor the Three Months
Ended September 30,Ended March 31,
2017 20162018 2017
(in millions)(in millions)
Cash flows from operating activities:   
Cash flows used for operating activities:   
Net income
$208.1
 
$199.3

$49.3
 
$39.8
Adjustments to reconcile net income to net cash flows from operating activities:   
Adjustments to reconcile net income to net cash flows used for operating activities:   
Depreciation and amortization181.0
 157.8
64.8
 53.6
Other26.2
 24.3
—
 3.1
Other changes in assets and liabilities:      
Accounts receivable12.4
 (66.5)(166.7) (147.0)
Sales of accounts receivable91.0
 (4.0)
Regulatory assets(107.8) (14.1)(3.3) (29.3)
Accounts payable(34.3) (24.7)
Regulatory liabilities(49.6) (64.5)21.7
 15.7
Deferred income taxes88.9
 67.7
11.2
 29.1
Other20.4
 (43.5)(7.9) 21.3
Net cash flows from operating activities470.6
 256.5
Cash flows used for investing activities:   
Utility construction and acquisition expenditures(470.1) (436.5)
Net cash flows used for operating activities(65.2) (38.4)
Cash flows from investing activities:   
Construction and acquisition expenditures(218.2) (127.6)
Cash receipts on sold receivables284.3
 214.7
Other(23.5) 1.1
(10.5) (8.7)
Net cash flows used for investing activities(493.6) (435.4)
Cash flows from financing activities:   
Net cash flows from investing activities55.6
 78.4
Cash flows from (used for) financing activities:   
Common stock dividends(117.0) (114.0)(41.9) (39.1)
Capital contributions from parent100.0
 65.0
Proceeds from issuance of long-term debt—
 300.0
Net change in commercial paper44.0
 —
45.9
 9.2
Other(2.6) 1.1
4.9
 (9.3)
Net cash flows from financing activities24.4
 252.1
Net increase in cash and cash equivalents1.4
 73.2
Cash and cash equivalents at beginning of period3.3
 4.5
Cash and cash equivalents at end of period
$4.7
 
$77.7
Net cash flows from (used for) financing activities8.9
 (39.2)
Net increase (decrease) in cash, cash equivalents and restricted cash(0.7) 0.8
Cash, cash equivalents and restricted cash at beginning of period7.2
 4.2
Cash, cash equivalents and restricted cash at end of period
$6.5
 
$5.0
Supplemental cash flows information:      
Cash (paid) refunded during the period for:   
Cash paid during the period for:   
Interest
($84.1) 
($72.5)
($28.2) 
($28.4)
Income taxes, net
$13.2
 
$0.7

$—
 
($2.6)
Significant non-cash investing and financing activities:      
Accrued capital expenditures
$71.0
 
$44.5

$68.3
 
$44.2
Beneficial interest obtained in exchange for securitized accounts receivable
$120.9
 
$149.0

The accompanying Combined Notes to Condensed Consolidated Financial Statements are an integral part of these statements.



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WISCONSIN POWER AND LIGHT COMPANY
CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)
For the Three Months For the Nine MonthsFor the Three Months
Ended September 30, Ended September 30,Ended March 31,
2017 2016 2017 20162018 2017
(in millions)(in millions)
Operating revenues:       
Revenues:   
Electric utility
$351.6
 
$381.1
 
$981.5
 
$999.9

$303.0
 
$321.4
Gas utility18.4
 15.6
 115.5
 106.1
77.5
 71.2
Other0.2
 0.3
 1.1
 0.9
1.2
 0.5
Total operating revenues370.2
 397.0
 1,098.1
 1,106.9
Total revenues381.7
 393.1
Operating expenses:          
Electric production fuel and purchased power100.1
 120.9
 284.7
 321.5
88.6
 98.3
Electric transmission service42.8
 42.7
 128.3
 126.1
35.6
 43.0
Cost of gas sold5.1
 4.5
 60.9
 56.0
50.6
 44.4
Other operation and maintenance66.1
 54.2
 179.7
 157.2
56.3
 54.4
Depreciation and amortization53.6
 48.7
 158.8
 143.5
54.6
 52.4
Taxes other than income taxes11.8
 11.0
 35.3
 33.8
12.0
 12.0
Total operating expenses279.5
 282.0
 847.7
 838.1
297.7
 304.5
Operating income90.7
 115.0
 250.4
 268.8
84.0
 88.6
Interest expense and other:       
Other (income) and deductions:   
Interest expense23.1
 22.9
 69.1
 68.7
24.7
 22.9
Equity income from unconsolidated investments(0.2) (9.3) (0.4) (29.0)
Allowance for funds used during construction(4.9) (2.0) (11.6) (8.1)(7.5) (2.7)
Interest income and other(0.1) 0.1
 (0.2) (0.2)
Total interest expense and other17.9
 11.7
 56.9
 31.4
Other1.1
 2.5
Total other (income) and deductions18.3
 22.7
Income before income taxes72.8
 103.3
 193.5
 237.4
65.7
 65.9
Income taxes23.0
 33.7
 60.1
 77.1
11.7
 20.4
Net income49.8
 69.6
 133.4
 160.3
Net income attributable to noncontrolling interest—
 0.6
 —
 1.6
Earnings available for common stock
$49.8
 
$69.0
 
$133.4
 
$158.7

$54.0
 
$45.5
Earnings per share data is not disclosed given Alliant Energy Corporation is the sole shareowner of all shares of WPL’s common stock outstanding during the periods presented.
The accompanying Combined Notes to Condensed Consolidated Financial Statements are an integral part of these statements.

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Table of Contents


WISCONSIN POWER AND LIGHT COMPANY
CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED)
September 30,
2017		 December 31,
2016		March 31,
2018		 December 31,
2017
(in millions, except per
share and share amounts)
(in millions, except per
share and share amounts)
ASSETS  
Current assets:      
Cash and cash equivalents
$3.2
 
$4.2

$3.7
 
$23.1
Accounts receivable, less allowance for doubtful accounts185.8
 226.3
192.0
 212.2
Production fuel, at weighted average cost24.2
 27.8
21.7
 19.9
Gas stored underground, at weighted average cost19.0
 21.3
12.7
 24.2
Materials and supplies, at weighted average cost43.6
 36.3
44.9
 42.1
Regulatory assets45.3
 40.1
36.8
 42.4
Other64.6
 60.5
57.7
 54.7
Total current assets385.7
 416.5
369.5
 418.6
Property, plant and equipment, net4,782.4
 4,426.7
4,962.6
 4,917.9
Other assets:      
Regulatory assets400.3
 416.2
396.4
 392.7
Deferred charges and other25.7
 30.9
29.4
 27.3
Total other assets426.0
 447.1
425.8
 420.0
Total assets
$5,594.1
 
$5,290.3

$5,757.9
 
$5,756.5
LIABILITIES AND EQUITY  
Current liabilities:      
Commercial paper
$224.6
 
$52.3

$30.6
 
$25.0
Accounts payable197.2
 192.9
134.6
 201.7
Accounts payable to associated companies28.1
 22.2
Regulatory liabilities59.2
 36.6
69.8
 70.3
Other108.7
 112.9
89.8
 77.0
Total current liabilities589.7
 394.7
352.9
 396.2
Long-term debt, net1,536.2
 1,535.2
1,833.7
 1,833.4
Other liabilities:      
Deferred tax liabilities1,035.2
 971.6
530.9
 522.4
Regulatory liabilities184.5
 213.6
690.8
 671.5
Capital lease obligations - Sheboygan Falls Energy Facility72.0
 77.2
65.8
 70.2
Pension and other benefit obligations204.2
 207.8
210.8
 213.7
Other162.6
 159.4
172.5
 167.6
Total other liabilities1,658.5
 1,629.6
1,670.8
 1,645.4
Commitments and contingencies (Note 12)

 
Commitments and contingencies (Note 13)

 
Equity:      
Wisconsin Power and Light Company common equity:      
Common stock - $5 par value - 18,000,000 shares authorized; 13,236,601 shares outstanding66.2
 66.2
66.2
 66.2
Additional paid-in capital1,059.0
 1,019.0
1,109.0
 1,109.0
Retained earnings684.5
 645.6
725.3
 706.3
Total Wisconsin Power and Light Company common equity1,809.7
 1,730.8
1,900.5
 1,881.5
Total liabilities and equity
$5,594.1
 
$5,290.3

$5,757.9
 
$5,756.5

The accompanying Combined Notes to Condensed Consolidated Financial Statements are an integral part of these statements.

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WISCONSIN POWER AND LIGHT COMPANY
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)
For the Nine MonthsFor the Three Months
Ended September 30,Ended March 31,
2017 20162018 2017
(in millions)(in millions)
Cash flows from operating activities:      
Net income
$133.4
 
$160.3

$54.0
 
$45.5
Adjustments to reconcile net income to net cash flows from operating activities:      
Depreciation and amortization158.8
 143.5
54.6
 52.4
Deferred tax expense and tax credits60.1
 97.9
6.7
 11.8
Other4.8
 (20.3)(4.7) 2.6
Other changes in assets and liabilities:      
Accounts receivable41.8
 (12.8)18.7
 13.3
Regulatory assets(1.1) 50.7
Accounts payable(23.0) (25.5)
Other(36.6) 20.0
35.4
 45.5
Net cash flows from operating activities361.2
 439.3
141.7
 145.6
Cash flows used for investing activities:      
Utility construction and acquisition expenditures(454.0) (307.1)
Construction and acquisition expenditures(117.0) (141.3)
Other(16.2) (19.6)(11.7) (8.0)
Net cash flows used for investing activities(470.2) (326.7)(128.7) (149.3)
Cash flows from (used for) financing activities:      
Common stock dividends(94.5) (101.2)(35.0) (31.5)
Capital contribution from parent40.0
 —
Net change in commercial paper172.3
 (8.1)5.6
 38.9
Other(9.8) 1.9
(1.9) (5.8)
Net cash flows from (used for) financing activities108.0
 (107.4)(31.3) 1.6
Net increase (decrease) in cash and cash equivalents(1.0) 5.2
Cash and cash equivalents at beginning of period4.2
 0.4
Cash and cash equivalents at end of period
$3.2
 
$5.6
Net decrease in cash, cash equivalents and restricted cash(18.3) (2.1)
Cash, cash equivalents and restricted cash at beginning of period24.2
 6.9
Cash, cash equivalents and restricted cash at end of period
$5.9
 
$4.8
Supplemental cash flows information:      
Cash (paid) refunded during the period for:   
Cash paid during the period for:   
Interest
($68.1) 
($67.7)
($21.5) 
($21.9)
Income taxes, net
($20.2) 
$19.6
Significant non-cash investing and financing activities:      
Accrued capital expenditures
$122.3
 
$50.8

$73.9
 
$90.5

The accompanying Combined Notes to Condensed Consolidated Financial Statements are an integral part of these statements.

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ALLIANT ENERGY CORPORATION
INTERSTATE POWER AND LIGHT COMPANY
WISCONSIN POWER AND LIGHT COMPANY

COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)

NOTE 1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
NOTE 1(a) General - The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the latest combined Annual Report on Form 10-K.

In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the ninethree months ended September 30, 2017March 31, 2018 are not necessarily indicative of results that may be expected for the year ending December 31, 2017.2018. A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred. Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.purposes, including modifications to the presentation of the components of net periodic benefit costs for defined benefit pension and other postretirement plans in the income statements as discussed in Note 1(d), restricted cash and cash receipts on sold receivables in the cash flows statements as discussed in Note 1(d), and segment reporting as discussed in Note 14.

Discontinued operations reported in Alliant Energy’s income statements is related to various warranty claims associated with the sale of RMT, Inc. in 2013, which have resulted in operating expenses and income subsequent to the sale.

NOTE 1(b) Cash, Cash Equivalents and Restricted Cash - At March 31, 2018 and December 31, 2017, restricted cash primarily related to deposits with trustees and borrowing requirements in Sheboygan Power, LLC’s debt agreement. Refer to Note 1(d) for discussion of revisions to the cash flows statements to include immaterial restricted cash amounts.

NOTE 1(c) Revenue Recognition -
Utility - Revenues from Alliant Energy’s utility business are primarily from retail and wholesale electric and gas sales to customers. Utility revenues are recognized over time as services are rendered or commodities are delivered to customers, and include billed and unbilled components. The billed component is based on the reading of customers’ meters, which occurs on a systematic basis throughout each reporting period and represents the fair value of the services provided or commodities delivered. The unbilled component is estimated and recorded at the end of each reporting period based on estimated amounts of energy delivered to customers since the date of each customer’s last meter reading. The unbilled revenue is based on estimates of daily system demand volumes, customer usage by class, temperature impacts, line losses and the most recent customer rates.

IPL and WPL accrue revenues from their wholesale customers to the extent that the actual net revenue requirements calculated in accordance with FERC-approved formula rates for the reporting period are higher or lower than the amounts billed to wholesale customers during such period. Regulatory assets or regulatory liabilities are recorded as the offset for these accrued revenues under formulaic rate-making programs. As of March 31, 2018, the related amounts accrued for IPL and WPL were not material.

IPL and WPL participate in bid/offer-based wholesale energy and ancillary services markets operated by MISO. The MISO transactions are grouped together, resulting in a net supply to or net purchase from MISO for each hour of each day. The net supply to MISO is recorded as bulk power sales in “Electric utility revenues” and the net purchase from MISO is recorded in “Electric production fuel and purchased power” in the income statements.

Non-utility - Revenues from Alliant Energy’s non-utility businesses are primarily from its Transportation business and are recognized over time as services are rendered or goods are delivered to customers.

Taxes Collected from Customers - Sales or various other taxes collected by certain of Alliant Energy’s subsidiaries on behalf of other agencies are recorded on a net basis and are not included in revenues.


12
Table of Contents

Other - Alliant Energy, IPL and WPL do not disclose the value of unsatisfied performance obligations for: (i) contracts with an original expected length of one year or less; and (ii) contracts for which revenue is recognized at the amount to which they have the right to invoice for goods delivered or services performed.

NOTE 1(d) New Accounting Standards -
Revenue Recognition - In May 2014, the Financial Accounting Standards Board issued an accounting standard providing principles for recognizing revenue for the transfer of promised goods or services to customers with the consideration to which the entity expects to be entitled in exchange for those goods or services. This standard also requires disclosures about the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. Alliant Energy, IPL and WPL will adoptadopted this standard on January 1, 2018 and currently expect to useusing the modified retrospective method of adoption. If applicable, this method requires a cumulative-effect adjustmentadoption, which was applied to the opening retained earnings balance oncontracts with customers that were completed subsequent to January 1, 2018, as if the standard had always been in effect.2018. Alliant Energy, IPL and WPL utilized a portfolio approach upon adoption, which involved evaluating portfolios of contracts with similar characteristics, where the effects of applying the standard were not expected to be materially different than evaluating on an individual contract basis. Upon adoption, there were no cumulative effect adjustments made to the January 1, 2018 retained earnings balances. In addition, prior period amounts have continuednot been restated to make progress inreflect the evaluationadoption of the revenue recognitionthis standard and do not currently anticipate a significant change in revenue recognition for retail electric and gas sales. These sales represent the majority of Alliant Energy’s, IPL’s and WPL’s revenues and are from tariff offerings that provide electricity or natural gas without a defined contractual term. For such arrangements, revenues from contracts with customers will be equivalent to the electricity or natural gas supplied and billed, or estimatedcontinue to be billed, and there will be no significant shiftreported under the accounting standards in the timing or pattern of revenue recognitioneffect for such sales. The most significant impact to the financial statements forthose periods. Alliant Energy, IPL and WPL is expected to bedid not have a material change in revenue recognition, including the form of additional disclosures. The incremental disclosures could include disaggregationtiming and pattern of revenue by location and customer class. Alliant Energy, IPL and WPL expect to complete the evaluationrecognition, as a result of the impactadoption of thethis standard. Refer to Notes 1(c) and 8 for further discussion of revenue recognition standard on their financial condition, results of operations and disclosures by January 1, 2018.recognition.

Leases - In February 2016, the Financial Accounting Standards Board issued an accounting standard requiring lease assets and lease liabilities, including operating leases, to be recognized on the balance sheet for all leases with terms longer than 12 months. The standard also requires disclosure of key information about leasing arrangements. Alliant Energy, IPL and WPL currently expect to adopt this standard on January 1, 2019 and are evaluating the impact of this standard on their financial condition and results of operations and expect an increase in assets and liabilities from recognizing operating leases on their balance sheets.

Presentation of Net Periodic Pension and Postretirement Benefit Costs - In March 2017, the Financial Accounting Standards Board issued an accounting standard amending the income statement presentation of the components of net periodic benefit costs for defined benefit pension and other postretirement plans. The standard requires entities to (1) disaggregate the current service cost component from the other components of net periodic benefit costs and present it with other employee compensation costs in the income statement; and (2) include the other components in the income statement outside of operating income. This new presentation will shift the majority of the net periodic benefit costs from “Other operation and maintenance” expenses to “Interest expense and other” expenses in the income statements. In addition, onlyOnly the service cost component of net periodic benefit costs is eligible for capitalization into property, plant and equipment, when

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applicable.equipment; however, IPL and WPL, as rate-regulated entities, currently expect to capitalize the other components of net periodic benefit costs into regulatory assets or regulatory liabilities. Alliant Energy, IPL and WPL will adoptadopted this standard on January 1, 2018. Upon2018 and used the retrospective method of adoption the standard must be applied retrospectively for the presentation requirements and prospectivelyprospective method of adoption for the capitalization requirements. Alliant Energy, IPL and WPL continueused the actual net periodic benefit costs adjusted for approximately 40% of net periodic benefit costs allocated to evaluate additional impactscapital projects for the retrospective method of adoption for the presentation requirements. The change in presentation resulted in a decrease in “Other operation and maintenance” expenses and an increase in “Other (income) and deductions” in the income statements of $4.3 million, $1.7 million and $2.6 million, respectively, for the three months ended March 31, 2017.

Cash Flows Statements - In August 2016, the Financial Accounting Standards Board issued an accounting standard providing specific guidance on several cash flow classification matters. The accounting standard requires classification of the consideration received for the beneficial interest obtained for transferring accounts receivable from IPL’s sales of accounts receivable program as an investing activity, instead of an operating activity. Alliant Energy, IPL and WPL adopted this standard on their financial conditionJanuary 1, 2018, which was applied retrospectively. For the three months ended March 31, 2017, Alliant Energy and resultsIPL reclassified $214.7 million of operations.the related cash received from IPL’s sales of accounts receivable program from operating activities to investing activities. The related impact on Alliant Energy’s and IPL’s cash flows statements for the year ended December 31, 2017 was $681.9 million.

In November 2016, the Financial Accounting Standards Board issued an accounting standard requiring restricted cash to be included within beginning-of-period and end-of-period cash and cash equivalents in the cash flows statements. Alliant Energy, IPL and WPL adopted this standard on January 1, 2018, which was applied retrospectively. Refer to Note 1(b) for further discussion of restricted cash.


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NOTE 2. REGULATORY MATTERS
Regulatory Assets and Regulatory Liabilities -
Regulatory assets were comprised of the following items (in millions):
Alliant Energy IPL WPLAlliant Energy IPL WPL
September 30,
2017		 December 31,
2016		 September 30,
2017		 December 31,
2016		 September 30,
2017		 December 31,
2016		March 31,
2018		 December 31,
2017		 March 31,
2018		 December 31,
2017		 March 31,
2018		 December 31,
2017
Tax-related
$1,147.9
 
$1,055.6
 
$1,107.9
 
$1,022.4
 
$40.0
 
$33.2

$795.1
 
$778.2
 
$762.8
 
$750.5
 
$32.3
 
$27.7
Pension and OPEB costs547.8
 578.7
 279.3
 294.0
 268.5
 284.7
538.6
 548.0
 270.0
 274.4
 268.6
 273.6
Asset retirement obligations107.9
 105.9
 71.9
 64.3
 36.0
 41.6
104.3
 109.3
 67.9
 72.5
 36.4
 36.8
EGUs retired early67.4
 41.4
 32.9
 —
 34.5
 41.4
60.1
 63.8
 30.4
 31.6
 29.7
 32.2
Derivatives49.9
 30.7
 22.3
 10.0
 27.6
 20.7
47.6
 45.3
 25.5
 21.8
 22.1
 23.5
Emission allowances25.6
 26.2
 25.6
 26.2
 —
 —
25.4
 25.5
 25.4
 25.5
 —
 —
Other90.0
 76.6
 51.0
 41.9
 39.0
 34.7
93.0
 96.6
 48.9
 55.3
 44.1
 41.3

$2,036.5
 
$1,915.1
 
$1,590.9
 
$1,458.8
 
$445.6
 
$456.3

$1,664.1
 
$1,666.7
 
$1,230.9
 
$1,231.6
 
$433.2
 
$435.1

Regulatory liabilities were comprised of the following items (in millions):
Alliant Energy IPL WPLAlliant Energy IPL WPL
September 30,
2017		 December 31,
2016		 September 30,
2017		 December 31,
2016		 September 30,
2017		 December 31,
2016		March 31,
2018		 December 31,
2017		 March 31,
2018		 December 31,
2017		 March 31,
2018		 December 31,
2017
Tax-related
$901.3
 
$899.4
 
$399.5
 
$399.5
 
$501.8
 
$499.9
Cost of removal obligations
$412.1
 
$411.6
 
$272.9
 
$269.4
 
$139.2
 
$142.2
415.6
 410.0
 274.7
 274.5
 140.9
 135.5
Electric transmission cost recovery94.8
 72.0
 35.9
 35.7
 58.9
 36.3
95.3
 90.4
 33.5
 26.4
 61.8
 64.0
Commodity cost recovery31.2
 21.0
 24.2
 14.6
 7.0
 6.4
IPL’s tax benefit riders45.0
 83.5
 45.0
 83.5
 —
 —
25.0
 25.0
 25.0
 25.0
 —
 —
Commodity cost recovery21.2
 30.8
 15.0
 17.8
 6.2
 13.0
Energy efficiency cost recovery20.0
 20.5
 —
 —
 20.0
 20.5
Derivatives10.9
 31.5
 5.8
 12.1
 5.1
 19.4
Other24.5
 31.1
 10.2
 12.3
 14.3
 18.8
69.5
 51.4
 20.4
 15.4
 49.1
 36.0

$628.5
 
$681.0
 
$384.8
 
$430.8
 
$243.7
 
$250.2

$1,537.9
 
$1,497.2
 
$777.3
 
$755.4
 
$760.6
 
$741.8

Tax-related - Alliant Energy’s and IPL’s tax-related regulatory assets are generally impacted by certain property-related differences at IPL for which deferred tax is not recorded in the income statement pursuant to Iowa rate-making principles. Deferred tax amounts for such property-related differences at IPL are recorded to regulatory assets, along with the necessary revenue requirement tax gross-ups. During the ninethree months ended September 30, 2017,March 31, 2018, Alliant Energy’s and IPL’s tax-related regulatory assets increased primarily due to property-related differences for qualifying repair expenditures.

Asset retirement obligationsOther - In September 2017, IPL reached a partial settlement agreement related to its retail electric rate review (2016 Test Year), subject to IUB approval. The proposed settlement does not include the recovery of certain asset retirement obligation costs previously recorded as regulatory assets, and as a result, Alliant Energy and IPL recorded a write-down of regulatory assets in the third quarter of 2017 as discussed in “IPL’s Retail Electric Rate Review (2016 Test Year)” below.

Electric generating units retired early - In June 2017, IPL retired Sutherland Units 1 and 3 and reclassified the remaining net book value of these EGUs from property, plant and equipment to a regulatory asset on Alliant Energy’s and IPL’s balance sheets. IPL is currently earning a return on the remaining net book value of these EGUs, as well as recovering the remaining net book value of these EGUs from both its retail and wholesale customers. IPL’s proposed settlement reached in September 2017 includes recovery of the remaining net book value of these EGUs from IPL’s retail customers over a 10-year period. However, the proposed settlement does not allow IPL to earn a return on the remaining net book value of these EGUs from its retail customers when final rates are implemented, and as a result, Alliant Energy and IPL recorded a write-down of regulatory assets in the third quarter of 2017 as discussed in “IPL’s Retail Electric Rate Review (2016 Test Year)” below. IPL has requested continued recovery of the remaining net book value of these EGUs from its retail customers over a 10-year period fromJanuary 2018, the IUB with a decision currently expected in the first quarter of 2018. In September 2017, FERC approved continued recovery of the remaining net book value of these EGUs from IPL’s wholesale customers over a 10-year period.


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Derivatives - Refer to Note 11 for discussion of derivative assets and derivative liabilities.

Electric transmission cost recovery - A group of MISO cooperative and municipal utilities previously filed two complaints with FERC requesting a reduction to the base return on equity used by MISO transmission owners, including ITC and ATC LLC, to determine electric transmission costs billed to utilities, including IPL and WPL. In September 2016, FERC issued an order onrequiring IPL and other investor-owned utilities in Iowa to track all calculated differences since January 1, 2018 resulting from Tax Reform, such that any over-collections can be refunded to its customers at a future date, if appropriate. In January 2018, the first complaintPSCW issued an order directing WPL and establishedother investor-owned utilities in Wisconsin to defer the revenue requirement impacts resulting from Tax Reform since its inception. As a base return on equityresult of 10.32%, excluding any incentive adders granted by FERC, effective September 28, 2016, and for the refund period from November 12, 2013 through February 11, 2015 (first complaint period). During the nine months ended September 30, 2017,these orders, as of March 31, 2018, Alliant Energy, IPL and WPL received the refunds for the first complaint period of $50deferred $19 million, $39$8 million and $11 million, respectively, after final true-ups. IPL and WPL each initially recordedrelated to Tax Reform, which is included in “Other” in the retail portion of the refunds to a regulatory liability. Pursuant to IUB approval, IPL’s retail portion of the refund from ITC is currently being refunded to its retail customers in 2017. WPL’s retail portion of the refund from ATC LLC will remain in a regulatory liability until such refunds are approved to be returned to retail customers in a future rate proceeding. IPL’s and WPL’s wholesale customers received their share of the refunds through normal monthly billing practices in 2017.

IPL’s tax benefit riders - IPL’s tax benefit riders utilize regulatory liabilities to credit bills of IPL’s Iowa retail electric and gas customers to help offset the impact of rate increases on such customers. These regulatory liabilities are related to tax benefits from tax accounting method changes for repairs expenditures and cost of removal expenditures, and a rate-making accounting change for capitalized interest. For the nine months ended September 30, 2017, Alliant Energy’s and IPL’s “IPL’s tax benefit riders” regulatory liabilities decreased by ($39) million as follows (in millions):table above.
Electric tax benefit rider credits
($51)
Gas tax benefit rider credits(5)
Rate-making accounting change17

($39)

In the third quarter of 2017, Alliant Energy and IPL implemented a rate-making accounting change for capitalized interest. IPL currently anticipates crediting its related tax benefits from this rate-making accounting change to its Iowa retail electric and gas customers in the future, and as a result, Alliant Energy and IPL recorded an increase of $17 million to IPL’s tax benefit riders regulatory liabilities during the nine months ended September 30, 2017.

Utility Rate Reviews -
IPL’s Retail ElectricGas Rate Review (2016(2017 Test Year) - In April 2017,May 2018, IPL filed a request with the IUB to increase annual electricgas base rates for its Iowa retail electricgas customers by $176$20 million, or approximately 12%8%. The request was based on a 20162017 historical Test Year as adjusted for certain known and measurable changes occurring up to 12 months after the commencement of the proceeding. The key drivers for the filing included recovery of capital projects, primarily power grid modernization and investments that advance cleaner energy, including Marshalltown.partially offset by the benefits of Tax Reform. An interim retail gas rate increase of $11 million, or approximately 5%, on an annual basis, will be implemented effective May 14, 2018. The interim rate increase does not require regulatory approval; however, it will be subject to refund pending determination of final rates. IPL currently expects a decision from the IUB in 2019 with final rates effective by the second quarter of 2019. The IUB must issue a decision on requests for retail rate changes within 10 months of the date of the application for which changes are filed.

IPL’s Retail Electric Rate Review (2016 Test Year) - In April 2017, IPL filed a request with the IUB to increase annual electric base rates for its Iowa retail electric customers. An interim retail electric base rate increase of $102 million, or approximately 7%, on an annual basis, was implemented effective April 13, 2017, without regulatory review, and will be subject to refund pending determination of final rates. Tax benefit rider credits and MISO transmission owner return on equity refunds are expected to reduce the effect of the rate increase on customer bills in 2017 and 2018. For the three and nine months ended September 30, 2017, Alliant Energy and IPL recorded increases in electric base rates of $34 million and $54 million, respectively, in conjunction with the interim retail electric base rate increase.

2017. In September 2017, IPL reached a partial, non-unanimous settlement agreement with the Iowa Office of Consumer Advocate, the Iowa Business Energy Coalition and the Large Energy Group for an annual electric base rate increase of $130 million, or approximately 9%. The final proposed rate increase (based on proposed settlement) includes increased depreciation expense resulting fromIn February 2018, the IUB issued an updated depreciation study; recovery over a four-year period of asset retirement obligation expenditures sinceorder approving the last retail electric rate filing in 2010; recovery over a 10-year period ofsettlement. Final rates were effective May 1, 2018. For the remaining net book value of Sutherland Units 1 and 3, unamortized forward contract costs for SO2 emission allowances through the energy adjustment clause and cancelled project costs approved in a prior emissions plan and budget; and no double leverage applied to the weighted-average cost of capital. The proposed settlement did not address rate design or IPL’s proposal to continue the electric transmission cost rider. As a result of the proposed settlement, in the third quarter of 2017, IPL recorded a write-down of regulatory assets of $9 million, including $4 million to “Other operation and maintenance” expenses primarily related to IPL being no longer probable of earning a return on the remaining net book value of Sutherland Units 1 and 3 from its retail customers when final rates are implemented, and $5 million to “Depreciation and amortization” expenses for asset retirement obligations deemed no longer probable of recovery in future rates. IPL currently expects to implement final rates in the first quarter of 2018. The IUB must issue a decision on requests for retail rate changes within 10three months of the date of the application for which changes are filed.

ended

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WPL’s Retail Electric and Gas Rate Review (2017/March 31, 2018, Test Period) - In December 2016, WPL received an order from the PSCW authorizing WPL to implement an increase in annual retail electric rates of $9 million, or approximately 1%, and an increase in annual retail gas base rates of $9 million, or approximately 13%. The $9 million net annual retail electric rate increase reflects a $60 million increase in base rates, partially offset by a $51 million reduction in fuel-related costs, using an estimate for 2017 fuel-related costs. These increases were effective January 1, 2017 and extend through the end of 2018. For the three and nine months ended September 30, 2017, Alliant Energy and WPLIPL recorded increases in electric base rates of $4$23 million and $42 million, and increases in gas base rates of $2 million and $6 million, respectively, in conjunction with the interim retail electric base rate increases authorized in the PSCW’s December 2016 order.

WPL’s Retail Fuel-related Rate Filing (2016 Test Year) - Pursuant to a 2015 PSCW order, WPL’s 2016 fuel-related costs were subject to deferral if they were outside an annual bandwidth of plus or minus 2% of the approved annual forecasted fuel-related costs. Retail fuel-related costs incurred by WPL in 2016 were lower than fuel-related costs used to determine rates for such period resulting in an over-collection of fuel-related costs. In August 2017, the PSCW authorized WPL to utilize $6 million of the over-collections as an offset to projected 2017 fuel-related cost under-collections. As of September 30, 2017, $3 million of remaining fuel-related costs for 2016 outside of the approved bandwidth are included in “Commodity cost recovery” in Alliant Energy’s and WPL’s regulatory liabilities table above, and these costs are expected to offset any rate changes for WPL’s 2018 fuel-related costs.

WPL’s Retail Fuel-related Rate Filing (2017 Test Year) - In March 2017, WPL filed an application with the PSCW for a mid-year fuel-related cost adjustment for 2017. Fuel-related costs for 2017 are currently expected to exceed the approved 2017 fuel-related cost plan by more than the 2% annual bandwidth. In August 2017, the PSCW authorized WPL to utilize $6 million of the 2016 fuel-related cost over-collections to offset a portion of the projected fuel-related cost under-collections for 2017. As of September 30, 2017, after applying the 2016 over-recovery amounts, the remaining fuel-related costs for 2017 outside of the approved bandwidth were $3 million and are included in “Other” in Alliant Energy’s and WPL’s regulatory assets table above.

WPL’s Retail Fuel-related Rate Filing (2018 Test Year) - In July 2017, WPL filed a request with the PSCW to increase annual rates for WPL’s retail electric customers by $6 million, or approximately 1%, in 2018. The increase primarily reflects a change in expected fuel-related costs in 2018, which are expected to be offset by $3 million of over-collections from WPL’s 2016 fuel-related costs as discussed above. Any rate changes granted from this request are expected to be effective January 1, 2018.increase.

NOTE 3. PROPERTY, PLANT AND EQUIPMENT
Utility -
Natural Gas-Fired Generation ProjectsProject -
IPL’s Marshalltown Generating Station - IPL’s construction of Marshalltown, an approximate 660 MW natural gas-fired combined-cycle EGU, was completed and the EGU was placed into service in April 2017. As of September 30, 2017, Alliant Energy and IPL recorded total project costs of $643 million and AFUDC of $81 million for Marshalltown in “Property, plant and equipment, net” on their balance sheets.

WPL’s West Riverside Energy Center - WPL is currently constructing West Riverside, an approximate 730 MW natural gas-fired combined-cycle EGU. Construction began in 2016 and is currently expected to be completed by early 2020. As of September 30, 2017,March 31, 2018, Alliant Energy and WPL recorded capitalized expenditures for construction work in progress of $278$347 million and AFUDC of $9$20 million for West Riverside in “Property, plant and equipment, net” on their balance sheets. These capital expenditures do not yet reflect any potential impacts from the exerciseWPL’s portion of purchase options by certainWest Riverside. Certain WPL electric cooperatives foracquired approximately 60 MW of West Riverside in January 2018, and will fund their share of capital expenditures during construction. As part of the electric cooperatives’ acquisitions, the current wholesale power supply agreements with the various electric cooperatives were extended by at least four years until 2026 with automatic continuation of such agreements unless terminated by either party, with a partial ownership interest in West Riverside.five-year notice requirement.

Wind Generation -
IPL’s Expansion of Wind Generation - IPL currently plans to add up to 1,000 MW of new wind projectsgeneration to its existing generation portfolio. These wind projects are expected to be placed into service in 2019 and 2020. As of September 30, 2017,March 31, 2018, Alliant Energy and IPL recorded capitalized expenditures for construction work in progress of $184$385 million and AFUDC of $7$16 million for this expansion of wind generation in “Property, plant and equipment, net” on their balance sheets.


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Franklin County Wind Farm - Based on an evaluation of the strategic options for the Franklin County wind farm performed in the third quarter of 2016, Alliant Energy concluded, as of September 30, 2016, it was probable the Franklin County wind farm would be transferred to IPL. As a result, Alliant Energy performed an impairment analysis of such assets and recorded non-cash, pre-tax asset valuation charges of $86 million (after-tax charges of $51 million, or $0.23 per share) in the third quarter of 2016. Alliant Energy recorded such charges as a reduction to property, plant and equipment on its balance sheet in 2016 and charges to “Asset valuation charges for Franklin County wind farm” in its income statements for the three and nine months ended September 30, 2016. The proposed settlement for IPL’s retail electric rate review (2016 Test Year) included recovery of the transfer price for the Franklin County wind farm.

In April 2017, the Franklin County wind farm was transferred from AEF to IPL as approved by a February 2017 FERC order. IPL’s purchase price, including certain transaction-related costs, was $32 million. As of the closing date, the estimated fair values of the assets purchased and liabilities assumed by IPL were as follows (in millions):
Electric plant in service
$40
Current assets2
Total assets acquired42
Other liabilities10
Net assets acquired
$32

WPL’s Proposed Acquisition of Forward Wind Energy Center (FWEC) - In October 2017,January 2018 and March 2018, WPL entered into definitive agreementsreceived approval from FERC and the PSCW, respectively, to acquire the assets of the Forward Wind Energy Center (FWEC),FWEC, which is a 129 MW wind farm located in Wisconsin. In April 2018, WPL currently expects to acquireacquired 55 MW of FWEC for approximately $74 million. WPL currently expects to file for approval from the PSCW and FERC in the fourth quarter of 2017, with decisions expected by the second quarter of 2018.

Retirement of IPL’s Sutherland Units 1 and 3 - In June 2017, IPL retired Sutherland Units 1 and 3 and reclassified the remaining net book value of these EGUs from property, plant and equipment to a regulatory asset on Alliant Energy’s and IPL’s balance sheets. Refer to Note 2 for further discussion.

NOTE 4. RECEIVABLES
Sales of Accounts Receivable - IPL maintains a Receivables Purchase and Sale Agreement (Receivables Agreement) whereby it may sell its customer accounts receivables, unbilled revenues and certain other accounts receivables to a third party through wholly-owned and consolidated special purpose entities. In March 2018, IPL amended and extended through March 2021 the purchase commitment from the third party to which it sells its receivables. Effective April 2018, the limit on cash proceeds will fluctuate between $90 million and $110 million. The transfers of receivables meet the criteria for sale accounting established by the transfer of financial assets accounting rules. As of September 30, 2017March 31, 2018, IPL had $1.5 million ofno available capacity under its sales of accounts receivable program. For the three and nine months ended September 30,March 31, 2018 and 2017, and 2016, IPL’s costs incurred related to the sales of accounts receivable program were not material.

IPL’s maximum and average outstanding cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program for the three and nine months ended September 30March 31 were as follows (in millions):
Three Months Nine Months
2017 2016 2017 20162018 2017
Maximum outstanding aggregate cash proceeds
$112.0
 
$172.0
 
$112.0
 
$172.0

$116.0
 
$79.0
Average outstanding aggregate cash proceeds66.2
 112.3
 58.7
 91.5
61.1
 38.4

The attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):
September 30, 2017 December 31, 2016March 31, 2018 December 31, 2017
Customer accounts receivable
$153.6
 
$157.6

$156.1
 
$133.8
Unbilled utility revenues89.1
 90.4
93.2
 112.7
Other receivables1.1
 0.1
0.3
 0.3
Receivables sold to third party243.8
 248.1
249.6
 246.8
Less: cash proceeds (a)112.0
 21.0
116.0
 12.0
Deferred proceeds131.8
 227.1
133.6
 234.8
Less: allowance for doubtful accounts16.5
 16.0
12.7
 12.7
Fair value of deferred proceeds
$115.3
 
$211.1

$120.9
 
$222.1

(a)Changes in cash proceeds are presented in “Sales of accounts receivable” in operating activities in Alliant Energy’s and IPL’s cash flows statements.


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As of September 30, 2017,March 31, 2018, outstanding receivables past due under the Receivables Agreement were $54.1$50.7 million. Additional attributes of IPL’s receivables sold under the Receivables Agreement for the three and nine months ended September 30March 31 were as follows (in millions):
 Three Months Nine Months
 2017 2016 2017 2016
Collections reinvested in receivables
$347.9
 
$499.7
 
$1,283.2
 
$1,362.1
Write-off losses (recoveries), net3.5
 (0.3) 10.4
 (0.6)

In connection with the implementation of IPL’s new customer billing and information system in 2016, IPL postponed the write-off of customer bills for a portion of 2016, resulting in lower write-offs for the three and nine months ended September 30, 2016.
 2018 2017
Collections
$517.0
 
$501.2
Write-offs, net of recoveries6.1
 4.6

NOTE 5. INVESTMENTS
NOTE 5(a) Unconsolidated Equity Investments -Equity Alliant Energy’s equity (income) loss from unconsolidated investments accounted for under the equity method of accounting for the three and nine months ended September 30March 31 was as follows (in millions):
Alliant Energy WPL2018 2017
Three Months Nine Months Three Months Nine Months
2017 2016 2017 2016 2017 2016 2017 2016
ATC Investment
($10.1) 
($9.1) 
($32.7) 
($28.6) 
$—
 
($9.1) 
$—
 
($28.6)
ATC Holdings
($8.7) 
($11.5)
Non-utility wind farm in Oklahoma(12.1) —
Other—
 (0.1) (0.2) (0.2) (0.2) (0.2) (0.4) (0.4)(0.5) —

($10.1) 
($9.2) 
($32.9) 
($28.8) 
($0.2) 
($9.3) 
($0.4) 
($29.0)
($21.3) 
($11.5)

ATC InvestmentNon-utility Wind Farm in Oklahoma - On December 31, 2016, pursuant toAlliant Energy’s interest in a June 2016 PSCW order, WPL Transco, LLC was liquidated and WPL transferred its investmentnon-utility wind farm in ATC LLC to ATI.Oklahoma commenced in July 2017. As a result, WPLthere was no longer recordscorresponding equity income from its prior investmentrecognized in ATC LLC. There were nothe first quarter of 2017. The equity income recognized in the first quarter of 2018 was primarily related to the impacts of this transferTax Reform. The liquidation method utilized to recognize Alliant Energy’s share of the wind farm’s earnings includes utilizing the federal income tax rate in effect as of the end of the measurement period. The lower federal income tax rate effective as of January 1, 2018 resulted in an acceleration of earnings attributable to Alliant Energy’s consolidated financial statements. As of December 31, 2016, ATI owns Alliant Energy’s entire investment in ATC.

Non-regulated Wind Investment in Oklahoma - In July 2017, a wholly-owned subsidiary of AEF acquired a 50% cash equity ownership interest in a 225 MW non-regulatedthe Oklahoma wind farm locatedfarm. This increase in Oklahoma, which started commercial operations in December 2016. The wind farm provides electricityearnings is expected to a third-party under a long-term purchased power agreement. In the third quarter of 2017, Alliant Energy’s “Other investments” assets increased $98 million from this acquisition. Alliant Energy will not maintain or operate the wind farm, and provided a parent guarantee of its subsidiary’s indemnification obligations under the operating agreement and purchased power agreement. Refer to Note 12(d) for discussion of the guarantee. Alliant Energy accounts for this non-regulated investment under the equity method of accounting, with the related equity (income) loss from unconsolidated investments included in the “Other” line in the above table. In conjunction with the acquisition, in July 2017, AEF entered into a $95 million, 364-day variable-rate term loan credit agreement (with Alliant Energy as guarantor).

NOTE 5(b) Cash Surrender Value of Life Insurance Policies - During the nine months ended September 30, 2016, certain of Alliant Energy’s and IPL’s company-owned life insurance policies were liquidated. The related proceeds of $31 million and $19 million were recorded in investing activities in Alliant Energy’s and IPL’s cash flows statements, respectively.reverse over time.

NOTE 6. COMMON EQUITY
Common Share Activity - A summary of Alliant Energy’s common stock activity was as follows:
Shares outstanding, January 1, 20172018227,673,654
At-the-market offering program3,074,931231,348,646
Shareowner Direct Plan issuances496,437166,527
Equity-based compensation plans (Note 9(b)10(b))
5,1855,078
Other(45,84738,423)
Shares outstanding, September 30, 2017March 31, 2018231,204,360231,481,828

At-the-Market Offering Program - In May 2017, Alliant Energy filed a prospectus supplement under which it could sell up to $125 million of its common stock through an at-the-market offering program. As of September 30, 2017, Alliant Energy issued 3,074,931 shares of common stock through this program and received cash proceeds of $124 million, net of $1 million in commissions and fees. The proceeds from the issuances of common stock were used for general corporate purposes. Alliant Energy currently has no plans to issue any additional common stock through this at-the-market offering program.


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Dividend Restrictions - As of September 30, 2017March 31, 2018, IPL’s amount of retained earnings that were free of dividend restrictions was $701683 million. As of September 30, 2017March 31, 2018, WPL’s amount of retained earnings that were free of dividend restrictions was $32105 million for the remainder of 20172018.

Restricted Net Assets of Subsidiaries - As of September 30, 2017March 31, 2018, the amount of IPL’s and WPL’s net assets that were not available to be transferred to their parent company, Alliant Energy, in the form of loans, advances or cash dividends without the consent of IPL’s and WPL’s regulatory authorities was $1.71.8 billion and $1.8 billion, respectively.

Comprehensive Income - For the three and nine months ended September 30, 2017March 31, 2018 and 20162017, Alliant Energy had no other comprehensive income; therefore, its comprehensive income was equal to its net income and its comprehensive income attributable to Alliant Energy common shareowners was equal to its net income attributable to Alliant Energy common shareowners for such periods. For the three and nine months ended September 30,March 31, 2018 and 2017, and 2016, IPL and WPL had no other comprehensive income; therefore, their comprehensive income was equal to their net income and their comprehensive income available for common stock was equal to their earnings available for common stock for such periods.

NOTE 7. DEBT
Note 7(a) Short-term Debt - In August 2017, Alliant Energy, IPL and WPL entered into a single new credit facility agreement, which expires in August 2022. The new credit facility agreement includes financial covenants similar to those that were included in the previous credit facility agreements. As of September 30, 2017, the short-term borrowing capacity under the new credit facility agreement totaled $1 billion ($300 million for Alliant Energy at the parent company level, $300 million for IPL and $400 million for WPL). Subject to certain conditions, Alliant Energy (at the parent company level), IPL and WPL may each reallocate and change its initial sublimit up to $500 million, $400 million and $500 million, respectively, within the $1 billion total commitment. Information regarding commercial paper classified as short-term debt was as follows (dollars in millions):
September 30, 2017Alliant Energy IPL WPL
March 31, 2018Alliant Energy IPL WPL
Commercial paper outstanding$390.3 $4.0 $224.6$336.4 $— $30.6
Commercial paper weighted average interest rates1.2% 1.4% 1.1%2.3% N/A 1.8%
Available credit facility capacity (a)$569.7 $256.0 $175.4$617.7 $204.1 $319.4

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Alliant Energy IPL WPLAlliant Energy IPL WPL
Three Months Ended September 302017 2016 2017 2016 2017 2016
Three Months Ended March 312018 2017 2018 2017 2018 2017
Maximum amount outstanding (based on daily outstanding balances)$424.4 $248.0 $20.0 $3.1 $271.2 $55.4$336.4 $325.5 $3.0 $9.2 $36.7 $113.6
Average amount outstanding (based on daily outstanding balances)$386.2 $220.1 $0.4 $0.1 $217.0 $36.4$310.1 $276.5 $— $0.1 $11.5 $79.1
Weighted average interest rates1.3% 0.6% 1.4% 0.6% 1.1% 0.4%1.9% 0.9% 1.8% 1.1% 1.6% 0.7%
Nine Months Ended September 30 
Maximum amount outstanding (based on daily outstanding balances)$424.4 $248.0 $20.0 $3.1 $271.2 $62.9
Average amount outstanding (based on daily outstanding balances)$323.9 $210.7 $0.5 $— $144.2 $33.2
Weighted average interest rates1.1% 0.6% 1.2% 0.6% 1.0% 0.4%

(a)Alliant Energy’s and IPL’s available credit facility capacities reflect outstanding commercial paper classified as both short- and long-term debt at September 30, 2017.March 31, 2018.

In July 2017, AEF entered into a $95 million, 364-day variable-rate (1.8% at September 30, 2017) term loan credit agreement (with Alliant Energy as guarantor) related to the acquisition of a non-regulated wind farm located in Oklahoma, which includes substantially the same financial covenants that are included in Alliant Energy’s current credit facility agreement. Refer to Note 5(a) for further discussion of the non-regulated wind farm acquisition.

NOTE 7(b) Long-term Debt - As of September 30, 2017, $40.0March 31, 2018, $45.9 million of commercial paper was recorded in “Long-term debt, net” on Alliant Energy’s and IPL’s balance sheets due to the existence of a long-term credit facility that back-stops this commercial paper balance, along with Alliant Energy’s and IPL’s intent and ability to refinance these balances on a long-term basis. As of September 30, 2017,March 31, 2018, this commercial paper balance had a 1.4%2.3% interest rate.

In October 2017, WPL issuedApril 2018, AEF entered into a $300 million of 3.05% debentures due 2027. Thevariable-rate (2.3% at April 30, 2018) term loan credit agreement (with Alliant Energy as guarantor) and used the proceeds from the issuance were used by WPL to reduce commercial paper andborrowings under this agreement for general corporate purposes. AEF’s term loan credit agreement expires in April 2020 and includes substantially the same financial covenants that are included in Alliant Energy’s credit facility agreement.

NOTE 8. REVENUES
Revenues from Alliant Energy’s, IPL’s and WPL’s utility businesses are primarily from retail and wholesale electric and gas sales provided to customers based on approved tariffs or specific contracts with customers. IPL’s and WPL’s primary performance obligations under such arrangements are to deliver electricity and gas, and their customers simultaneously receive and consume the electricity and gas. For such arrangements, revenues are recognized equivalent to the value of the electricity or gas supplied during each period, including amounts billed during each period and changes in amounts estimated to be billed at the end of each period. IPL and WPL apply the right to invoice method to measure progress towards completing performance obligations to transfer electricity and gas to their customers.

IPL provides retail electric and gas service to customers in Iowa, and WPL provides retail and wholesale electric and retail gas service to customers in Wisconsin. IPL also sells electricity to wholesale customers in Minnesota, Illinois and Iowa, as well as steam from its Prairie Creek Generating Station to high-pressure steam customers in Iowa.

IPL’s and WPL’s retail electric and gas revenues include sales to residential, commercial and industrial customers. IPL’s and WPL’s retail electric and gas customer prices are based on IPL’s and WPL’s cost of service and are determined through general rate review proceedings and various tariff filings with the IUB and PSCW, respectively. Such tariff-based services provide electricity or gas to customers without a defined contractual term.

IPL and WPL have wholesale electric market-based rate authority from FERC allowing them to participate in wholesale energy markets (e.g. MISO) and transact directly with third parties. This authority from FERC allows sales of electricity referred to as bulk power sales based on current market values. FERC also allows IPL and WPL to enter into power supply agreements with municipalities and rural electric cooperatives with defined contractual terms, which include standard pricing mechanisms that are detailed in current tariffs accepted by FERC through wholesale rate review proceedings.

Revenues from Alliant Energy’s non-utility business customers are primarily from its Transportation business, which includes a short-line railway that provides freight service between Cedar Rapids, Iowa and Iowa City, Iowa; a barge terminal and hauling services on the Mississippi River; and other transfer and storage services.

As of March 31, 2018, revenue expected to be recognized in any future year related to remaining performance obligations is not material, as the majority of revenues are recognized as services are rendered or commodities are delivered, and are from contracts with durations of less than one year. Alliant Energy, IPL and WPL do not have any material contract assets or contract liabilities, or contract acquisition fulfillment costs.


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Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions):
 Alliant Energy IPL WPL
Three Months Ended March 312018 2017 2018 2017 2018 2017
Electric Utility:           
Retail - residential
$259.4
 
$241.2
 
$142.2
 
$123.3
 
$117.2
 
$117.9
Retail - commercial174.0
 165.7
 111.6
 99.5
 62.4
 66.2
Retail - industrial201.9
 195.0
 114.8
 103.9
 87.1
 91.1
Wholesale53.8
 63.4
 24.3
 21.3
 29.5
 42.1
Bulk power and other19.6
 12.3
 12.8
 8.2
 6.8
 4.1
Total Electric Utility708.7
 677.6
 405.7
 356.2
 303.0
 321.4
Gas Utility:           
Retail - residential110.6
 89.9
 65.5
 47.9
 45.1
 42.0
Retail - commercial57.0
 49.8
 31.6
 25.8
 25.4
 24.0
Retail - industrial5.8
 4.8
 2.7
 2.8
 3.1
 2.0
Transportation/other12.2
 9.8
 8.3
 6.6
 3.9
 3.2
Total Gas Utility185.6
 154.3
 108.1
 83.1
 77.5
 71.2
Other Utility:           
Steam9.4
 8.6
 9.4
 8.6
 —
 —
Other utility3.8
 3.1
 2.6
 2.6
 1.2
 0.5
Total Other Utility13.2
 11.7
 12.0
 11.2
 1.2
 0.5
Non-Utility and Other:           
Transportation and other8.8
 10.3
 —
 —
 —
 —
Total Non-Utility and Other8.8
 10.3
 —
 —
 —
 —
Total revenues
$916.3
 
$853.9
 
$525.8
 
$450.5
 
$381.7
 
$393.1

NOTE 8.9. INCOME TAXES
Income Tax Rates - The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.
 Alliant Energy IPL WPL
Three Months Ended September 302017 2016 2017 2016 2017 2016
Statutory federal income tax rate35.0 % 35.0 % 35.0% 35.0% 35.0 % 35.0 %
Effect of rate-making on property-related differences(10.1) (11.9) (22.6) (16.5) (1.9) (0.7)
IPL’s tax benefit riders(8.3) (13.1) (20.9) (20.1) —
 —
Production tax credits(6.2) (9.0) (7.0) (6.0) (7.0) (5.7)
Other items, net2.8
 4.4
 2.3
 5.4
 5.5
 4.0
Overall income tax rate13.2% 5.4% (13.2%) (2.2%) 31.6% 32.6%
Alliant Energy IPL WPLAlliant Energy IPL WPL
Nine Months Ended September 302017 2016 2017 2016 2017 2016
Three Months Ended March 312018 2017 2018 2017 2018 2017
Statutory federal income tax rate35.0 % 35.0 % 35.0% 35.0% 35.0 % 35.0 %21.0 % 35.0 % 21.0% 35.0% 21.0 % 35.0 %
State income taxes, net of federal benefits7.5
 5.4
 8.5
 6.3
 6.2
 5.1
Effect of rate-making on property-related differences(9.1) (8.2) (20.6) (14.8) (1.8) (0.8)(7.4) (7.5) (13.5) (17.9) (2.4) (1.7)
Production tax credits(5.5) (5.9) (5.4) (6.6) (6.7) (7.0)
IPL’s tax benefit riders(8.1) (10.2) (20.1) (19.6) —
 —
(2.2) (7.8) (4.7) (19.4) —
 —
Production tax credits(6.0) (7.2) (6.8) (6.1) (7.0) (6.1)
Other items, net3.1
 3.5
 2.7
 4.2
 4.9
 4.4
(1.4) (4.4) —
 (7.6) (0.3) (0.4)
Overall income tax rate14.9% 12.9% (9.8%) (1.3%) 31.1% 32.5%12.0% 14.8% 5.9% (10.2%) 17.8% 31.0%

Deferred Tax Assets and Liabilities - For the ninethree months ended September 30, 2017,March 31, 2018, Alliant Energy’s, IPL’s and WPL’s deferred tax liabilities increased $204.5$33.2 million, $131.7$15.8 million and $63.6$8.5 million, respectively. These increases were primarily due to property-related differences recordedand the utilization of federal net operating losses during the ninethree months ended September 30, 2017. Alliant Energy’s and IPL’sMarch 31, 2018. These increases were partially offset by the generation ofan increase in federal net operating lossescredit carryforwards recorded during the ninethree months ended September 30, 2017, which are primarily due to accelerated tax depreciation associated with Marshalltown.March 31, 2018.

Carryforwards - At September 30, 2017,March 31, 2018, carryforwards and expiration dates were estimated as follows (in millions):
Range of Expiration Dates Alliant Energy IPL WPLRange of Expiration Dates Alliant Energy IPL WPL
Federal net operating losses2030-2037 
$815
 
$500
 
$208
2030-2037 
$774
 
$497
 
$176
State net operating losses2018-2037 701
 14
 2
2018-2038 707
 13
 2
Federal tax credits2022-2037 297
 110
 125
2022-2038 277
 123
 136


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NOTE 9.10. BENEFIT PLANS
NOTE 9(a)10(a) Pension and Other Postretirement Benefits Plans -
Net Periodic Benefit Costs - The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and nine months ended September 30March 31 are included in the tables below (in millions). The service cost component of net periodic benefit costs is included in “Other operation and maintenance” expenses in the income statements and all other components of net periodic benefit costs are included in “Other (income) and deductions” in the income statements. In IPL’s and WPL’s tables below, the defined benefit pension plan amounts represent those respective amounts for their bargaining unit employees covered under the qualified plans that they sponsor, as well as amounts directly assigned to them related to their current and former non-bargaining employees who are participants in the Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans. In IPL’s and WPL’s tables below, the OPEB plansplan amounts represent respective amounts for their employees, as well as amounts directly assigned to them related to their current and former non-bargaining employees who are participants in the Corporate Services sponsored OPEB plan.
 Defined Benefit Pension Plans OPEB Plans
 Three Months Nine Months Three Months Nine Months
Alliant Energy2017 2016 2017 2016 2017 2016 2017 2016
Service cost
$3.1
 
$3.2
 
$9.3
 
$9.5
 
$1.2
 
$1.4
 
$3.7
 
$4.0
Interest cost12.7
 13.2
 38.3
 39.7
 2.2
 2.3
 6.5
 7.0
Expected return on plan assets(16.3) (16.3) (49.1) (49.1) (1.5) (1.6) (4.6) (4.6)
Amortization of prior service credit(0.1) (0.1) (0.3) (0.2) (0.1) (1.0) (0.2) (3.1)
Amortization of actuarial loss9.4
 9.3
 28.2
 28.0
 1.0
 1.2
 2.9
 3.6
Settlement losses (a)0.9
 —
 0.9
 —
 —
 —
 —
 —
 
$9.7
 
$9.3
 
$27.3
 
$27.9
 
$2.8
 
$2.3
 
$8.3
 
$6.9

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 Defined Benefit Pension Plans OPEB Plans
Alliant Energy2018 2017 2018 2017
Service cost
$3.0
 
$3.1
 
$1.1
 
$1.2
Interest cost11.7
 12.8
 1.9
 2.2
Expected return on plan assets(17.4) (16.4) (1.5) (1.5)
Amortization of prior service credit(0.2) (0.1) —
 (0.1)
Amortization of actuarial loss8.8
 9.4
 0.8
 1.0
 
$5.9
 
$8.8
 
$2.3
 
$2.8
Defined Benefit Pension Plans OPEB Plans
Three Months Nine Months Three Months Nine MonthsDefined Benefit Pension Plans OPEB Plans
IPL2017 2016 2017 2016 2017 2016 2017 20162018 2017 2018 2017
Service cost
$1.8
 
$1.8
 
$5.5
 
$5.6
 
$0.5
 
$0.5
 
$1.6
 
$1.7

$1.8
 
$1.8
 
$0.4
 
$0.5
Interest cost5.9
 6.1
 17.6
 18.4
 0.8
 1.0
 2.6
 2.9
5.3
 5.9
 0.8
 0.9
Expected return on plan assets(7.7) (7.7) (23.1) (23.2) (1.0) (1.0) (3.2) (3.2)(8.1) (7.7) (1.1) (1.1)
Amortization of prior service credit—
 —
 (0.1) (0.1) —
 (0.7) —
 (2.0)
Amortization of actuarial loss4.0
 4.2
 12.1
 12.4
 0.5
 0.7
 1.5
 2.0
3.7
 4.0
 0.3
 0.5

$4.0
 
$4.4
 
$12.0
 
$13.1
 
$0.8
 
$0.5
 
$2.5
 
$1.4

$2.7
 
$4.0
 
$0.4
 
$0.8
Defined Benefit Pension Plans OPEB Plans
Three Months Nine Months Three Months Nine MonthsDefined Benefit Pension Plans OPEB Plans
WPL2017 2016 2017 2016 2017 2016 2017 20162018 2017 2018 2017
Service cost
$1.2
 
$1.3
 
$3.6
 
$3.7
 
$0.5
 
$0.5
 
$1.4
 
$1.5

$1.1
 
$1.2
 
$0.4
 
$0.5
Interest cost5.5
 5.5
 16.4
 16.7
 0.9
 0.9
 2.6
 2.8
5.0
 5.5
 0.8
 0.9
Expected return on plan assets(7.2) (7.0) (21.4) (21.2) (0.2) (0.2) (0.6) (0.6)(7.6) (7.1) (0.2) (0.2)
Amortization of prior service cost (credit)0.1
 —
 0.1
 0.1
 (0.1) (0.3) (0.2) (0.7)
Amortization of prior service credit—
 —
 —
 (0.1)
Amortization of actuarial loss4.6
 4.4
 13.9
 13.2
 0.4
 0.5
 1.2
 1.4
4.3
 4.6
 0.5
 0.4

$4.2
 
$4.2
 
$12.6
 
$12.5
 
$1.5
 
$1.4
 
$4.4
 
$4.4

$2.8
 
$4.2
 
$1.5
 
$1.5

(a)Settlement losses related to payments made to retired executives of Alliant Energy.

NOTE 9(b)10(b) Equity-based Compensation Plans - A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards for the three and nine months ended September 30March 31 was as follows (in millions):
Alliant Energy IPL WPL
Three Months Nine Months Three Months Nine Months Three Months Nine MonthsAlliant Energy IPL WPL
2017 2016 2017 2016 2017 2016 2017 2016 2017 2016 2017 20162018 2017 2018 2017 2018 2017
Compensation expense
$5.1
 
$4.4
 
$9.9
 
$16.8
 
$2.8
 
$2.4
 
$5.4
 
$8.9
 
$2.1
 
$1.9
 
$4.1
 
$7.3

$3.3
 
$3.2
 
$1.8
 
$1.7
 
$1.3
 
$1.4
Income tax benefits2.1
 1.7
 4.0
 6.8
 1.1
 1.0
 2.2
 3.7
 0.9
 0.7
 1.7
 2.9
0.9
 1.3
 0.5
 0.7
 0.4
 0.5

As of September 30, 2017,March 31, 2018, Alliant Energy’s, IPL’s and WPL’s total unrecognized compensation cost related to share-based compensation awards was $8.5$14.6 million, $4.7$8.1 million and $3.5$5.9 million, respectively, which is expected to be recognized over a weighted average period of between one and two years.


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Performance Shares and Performance Units - A summary of the performance shares and performance units activity for the ninethree months ended September 30, 2017,March 31, 2018, with amounts representing the target number of awards, was as follows:
Performance Shares Performance UnitsPerformance Shares Performance Units
Nonvested awards, January 1257,599
 93,320
223,511
 71,737
Granted65,350
 21,558
74,163
 19,840
Vested(99,438) (37,395)(90,806) (31,910)
Forfeited—
 (4,243)
Nonvested awards, September 30223,511
 73,240
Nonvested awards, March 31206,868
 59,667

Vested Awards - During the ninethree months ended September 30, 2017,March 31, 2018, certain performance shares and performance units that were granted in 20142015 vested, resulting in payouts (a combination of cash and common stock for the performance shares and cash only for the performance units) as follows:
Performance Shares Performance UnitsPerformance Shares Performance Units
Performance awards vested99,438
 37,395
90,806
 31,910
Percentage of target number of performance awards147.5% 147.5%137.5% 137.5%
Aggregate payout value (in millions)
$5.6
 
$1.5

$5.3
 
$1.4
Payout - cash (in millions)
$5.1
 
$1.5

$4.9
 
$1.4
Payout - common stock shares issued5,185
 N/A
5,078
 N/A

Fair Value of Awards - At March 29, 2018, Alliant Energy’s common stock closing price was $40.86. Additional information related to fair values of nonvested performance shares and performance units at March 31, 2018, by year of grant, was as follows:
 Performance Shares Performance Units
 2018 Grant 2017 Grant 2016 Grant 2018 Grant 2017 Grant 2016 Grant
Nonvested awards at target74,163
 65,350
 67,355
 19,840
 18,600
 21,227
Estimated payout percentage based on performance criteria100% 115% 160% 100% 115% 160%
Fair values of each nonvested award
$40.86
 
$46.99
 
$65.38
 
$40.86
 
$46.99
 
$65.38

Performance Restricted Stock Units - A summary of the performance restricted stock units activity for the three months ended March 31, 2018, with amounts representing the target number of units, was as follows:
 Units 
Weighted Average
Grant Date Fair Value
Nonvested units, January 1132,705
 
$36.50
Granted74,163
 38.60
Nonvested units, March 31206,868
 37.25

Restricted Stock Units - A summary of the restricted stock units activity for the three months ended March 31, 2018, was as follows:
Nonvested units, January 1113,749
Granted63,568
Nonvested units, March 31177,317


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Fair Value of Awards - Information related to fair values of nonvested performance shares and performance units at September 30, 2017, by year of grant, was as follows:
 Performance Shares Performance Units
 2017 Grant 2016 Grant 2015 Grant 2017 Grant 2016 Grant 2015 Grant
Nonvested awards at target65,350
 67,355
 90,806
 19,531
 21,751
 31,958
Alliant Energy common stock closing price on September 29, 2017
$41.57
 
$41.57
 
$41.57
 
$41.57
 
$41.57
 N/A
Alliant Energy common stock closing price on grant dateN/A N/A N/A N/A N/A 
$32.55
Estimated payout percentage based on performance criteria100% 138% 113% 100% 138% 113%
Fair values of each nonvested award
$41.57
 
$57.37
 
$46.97
 
$41.57
 
$57.37
 
$36.78

Performance Restricted Stock Units - A summary of the performance restricted stock units activity for the nine months ended September 30, 2017, with amounts representing the target number of units, was as follows:
 Units 
Weighted Average
Grant Date Fair Value
Nonvested units, January 167,355
 
$33.96
Granted65,350
 39.12
Nonvested units, September 30132,705
 36.50

Restricted Stock Units - A summary of the restricted stock units activity for the nine months ended September 30, 2017, was as follows:
Nonvested units, January 157,736
Granted56,013
Nonvested units, September 30113,749

NOTE 10.11. FAIR VALUE MEASUREMENTS
Valuation Hierarchy - At each reporting date, Level 1 items included IPL’s 5.1% cumulative preferred stock, Level 2 items included certain non-exchange traded commodity contracts and substantially all of the long-term debt instruments, and Level 3 items included FTRs, certain non-exchange traded commodity contracts and IPL’s deferred proceeds.

Fair Value of Financial Instruments - The carrying amounts of current assets and current liabilities approximate fair value because of the short maturity of such financial instruments. Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):
Alliant EnergySeptember 30, 2017 December 31, 2016March 31, 2018 December 31, 2017
  Fair Value   Fair Value  Fair Value   Fair Value
Carrying Level Level Level   Carrying Level Level Level  Carrying Level Level Level   Carrying Level Level Level  
Amount 1 2 3 Total Amount 1 2 3 TotalAmount 1 2 3 Total Amount 1 2 3 Total
Assets:                                      
Derivatives
$29.4
 
$—
 
$2.9
 
$26.5
 
$29.4
 
$41.4
 
$—
 
$4.6
 
$36.8
 
$41.4

$14.1
 
$—
 
$4.1
 
$10.0
 
$14.1
 
$25.1
 
$—
 
$4.1
 
$21.0
 
$25.1
Deferred proceeds115.3
 —
 —
 115.3
 115.3
 211.1
 —
 —
 211.1
 211.1
120.9
 —
 —
 120.9
 120.9
 222.1
 —
 —
 222.1
 222.1
Liabilities and equity:                                      
Derivatives45.1
 —
 14.9
 30.2
 45.1
 28.6
 —
 0.5
 28.1
 28.6
46.7
 —
 7.3
 39.4
 46.7
 41.7
 —
 8.5
 33.2
 41.7
Long-term debt (incl. current maturities)4,360.3
 —
 4,893.3
 2.9
 4,896.2
 4,320.2
 —
 4,795.7
 3.3
 4,799.0
4,912.5
 —
 5,366.6
 2.5
 5,369.1
 4,866.3
 —
 5,444.6
 2.9
 5,447.5
Cumulative preferred stock of IPL200.0
 202.3
 —
 —
 202.3
 200.0
 194.8
 —
 —
 194.8
200.0
 198.4
 —
 —
 198.4
 200.0
 203.8
 —
 —
 203.8
IPLMarch 31, 2018 December 31, 2017
   Fair Value   Fair Value
 Carrying Level Level Level   Carrying Level Level Level  
 Amount 1 2 3 Total Amount 1 2 3 Total
Assets:                   
Derivatives
$7.9
 
$—
 
$1.7
 
$6.2
 
$7.9
 
$17.1
 
$—
 
$2.0
 
$15.1
 
$17.1
Deferred proceeds120.9
 —
 —
 120.9
 120.9
 222.1
 —
 —
 222.1
 222.1
Liabilities and equity:                   
Derivatives24.7
 —
 3.1
 21.6
 24.7
 19.4
 —
 2.9
 16.5
 19.4
Long-term debt (incl. current maturities)2,452.2
 —
 2,635.7
 —
 2,635.7
 2,406.0
 —
 2,665.7
 —
 2,665.7
Cumulative preferred stock200.0
 198.4
 —
 —
 198.4
 200.0
 203.8
 —
 —
 203.8
WPLMarch 31, 2018 December 31, 2017
   Fair Value   Fair Value
 Carrying Level Level Level   Carrying Level Level Level  
 Amount 1 2 3 Total Amount 1 2 3 Total
Assets:                   
Derivatives
$6.2
 
$—
 
$2.4
 
$3.8
 
$6.2
 
$8.0
 
$—
 
$2.1
 
$5.9
 
$8.0
Liabilities:                   
Derivatives22.0
 —
 4.2
 17.8
 22.0
 22.3
 —
 5.6
 16.7
 22.3
Long-term debt1,833.7
 —
 2,102.7
 —
 2,102.7
 1,833.4
 —
 2,147.9
 —
 2,147.9

Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):
Alliant EnergyCommodity Contract Derivative  
 Assets and (Liabilities), net Deferred Proceeds
Three Months Ended March 312018 2017 2018 2017
Beginning balance, January 1
($12.2) 
$8.7
 
$222.1
 
$211.1
Total net losses included in changes in net assets (realized/unrealized)(9.8) (35.2) —
 —
Sales—
 (0.1) —
 —
Settlements (a)(7.4) (6.3) (101.2) (62.1)
Ending balance, March 31
($29.4) 
($32.9) 
$120.9
 
$149.0
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at March 31
($9.4) 
($33.7) 
$—
 
$—

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IPLSeptember 30, 2017 December 31, 2016
   Fair Value   Fair Value
 Carrying Level Level Level   Carrying Level Level Level  
 Amount 1 2 3 Total Amount 1 2 3 Total
Assets:                   
Derivatives
$21.1
 
$—
 
$1.6
 
$19.5
 
$21.1
 
$20.8
 
$—
 
$2.8
 
$18.0
 
$20.8
Deferred proceeds115.3
 —
 —
 115.3
 115.3
 211.1
 —
 —
 211.1
 211.1
Liabilities and equity:                   
Derivatives18.7
 —
 4.5
 14.2
 18.7
 8.3
 —
 0.4
 7.9
 8.3
Long-term debt (incl. current maturities)2,195.0
 —
 2,430.1
 —
 2,430.1
 2,153.5
 —
 2,352.3
 —
 2,352.3
Cumulative preferred stock200.0
 202.3
 —
 —
 202.3
 200.0
 194.8
 —
 —
 194.8
IPLCommodity Contract Derivative  
 Assets and (Liabilities), net Deferred Proceeds
Three Months Ended March 312018 2017 2018 2017
Beginning balance, January 1
($1.4) 
$10.1
 
$222.1
 
$211.1
Total net losses included in changes in net assets (realized/unrealized)(7.6) (12.7) —
 —
Sales—
 (0.1) —
 —
Settlements (a)(6.4) (5.6) (101.2) (62.1)
Ending balance, March 31
($15.4) 
($8.3) 
$120.9
 
$149.0
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at March 31
($7.3) 
($11.4) 
$—
 
$—
WPLSeptember 30, 2017 December 31, 2016
   Fair Value   Fair Value
 Carrying Level Level Level   Carrying Level Level Level  
 Amount 1 2 3 Total Amount 1 2 3 Total
Assets:                   
Derivatives
$8.3
 
$—
 
$1.3
 
$7.0
 
$8.3
 
$20.6
 
$—
 
$1.8
 
$18.8
 
$20.6
Liabilities:                   
Derivatives26.4
 —
 10.4
 16.0
 26.4
 20.3
 —
 0.1
 20.2
 20.3
Long-term debt1,536.2
 —
 1,829.3
 —
 1,829.3
 1,535.2
 —
 1,807.4
 —
 1,807.4

Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):
Alliant EnergyCommodity Contract Derivative  
 Assets and (Liabilities), net Deferred Proceeds
Three Months Ended September 302017 2016 2017 2016
Beginning balance, July 1
$9.2
 
$0.6
 
$170.0
 
$74.4
Total net losses included in changes in net assets (realized/unrealized)(4.3) (5.1) —
 —
Transfers out of Level 3—
 0.8
 —
 —
Sales(0.1) (0.2) —
 —
Settlements (a)(8.5) (4.0) (54.7) 165.3
Ending balance, September 30
($3.7) 
($7.9) 
$115.3
 
$239.7
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30
($4.2) 
($5.0) 
$—
 
$—
Alliant EnergyCommodity Contract Derivative  
 Assets and (Liabilities), net Deferred Proceeds
Nine Months Ended September 302017 2016 2017 2016
Beginning balance, January 1
$8.7
 
($32.7) 
$211.1
 
$172.0
Total net gains (losses) included in changes in net assets (realized/unrealized)(31.3) 8.0
 —
 —
Transfers into Level 3—
 0.9
 —
 —
Transfers out of Level 312.2
 1.2
 —
 —
Purchases28.3
 22.0
 —
 —
Sales(0.3) (0.9) —
 —
Settlements (a)(21.3) (6.4) (95.8) 67.7
Ending balance, September 30
($3.7) 
($7.9) 
$115.3
 
$239.7
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30
($29.4) 
$9.7
 
$—
 
$—

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IPLCommodity Contract Derivative  
 Assets and (Liabilities), net Deferred Proceeds
Three Months Ended September 302017 2016 2017 2016
Beginning balance, July 1
$17.1
 
$18.3
 
$170.0
 
$74.4
Total net losses included in changes in net assets (realized/unrealized)(4.4) (0.4) —
 —
Transfers out of Level 3—
 0.3
 —
 —
Sales(0.1) (0.2) —
 —
Settlements (a)(7.3) (4.6) (54.7) 165.3
Ending balance, September 30
$5.3
 
$13.4
 
$115.3
 
$239.7
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30
($4.5) 
($0.4) 
$—
 
$—
IPLCommodity Contract Derivative  
 Assets and (Liabilities), net Deferred Proceeds
Nine Months Ended September 302017 2016 2017 2016
Beginning balance, January 1
$10.1
 
($1.9) 
$211.1
 
$172.0
Total net gains (losses) included in changes in net assets (realized/unrealized)(13.9) 4.8
 —
 —
Transfers into Level 3—
 0.5
 —
 —
Transfers out of Level 33.1
 0.2
 —
 —
Purchases24.6
 20.6
 —
 —
Sales(0.2) (0.9) —
 —
Settlements (a)(18.4) (9.9) (95.8) 67.7
Ending balance, September 30
$5.3
 
$13.4
 
$115.3
 
$239.7
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30
($12.6) 
$5.7
 
$—
 
$—
WPLCommodity Contract Derivative
 Assets and (Liabilities), net
Three Months Ended September 302017 2016
Beginning balance, July 1
($7.9) 
($17.7)
Total net gains (losses) included in changes in net assets (realized/unrealized)0.1
 (4.7)
Transfers out of Level 3—
 0.5
Settlements(1.2) 0.6
Ending balance, September 30
($9.0) 
($21.3)
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30
$0.3
 
($4.6)
WPLCommodity Contract Derivative
 Assets and (Liabilities), net
Nine Months Ended September 302017 2016
Beginning balance, January 1
($1.4) 
($30.8)
Total net gains (losses) included in changes in net assets (realized/unrealized)(17.4) 3.2
Transfers into Level 3—
 0.4
Transfers out of Level 39.1
 1.0
Purchases3.7
 1.4
Sales(0.1) —
Settlements(2.9) 3.5
Ending balance, September 30
($9.0) 
($21.3)
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30
($16.8) 
$4.0
WPLCommodity Contract Derivative
 Assets and (Liabilities), net
Three Months Ended March 312018 2017
Beginning balance, January 1
($10.8) 
($1.4)
Total net losses included in changes in net assets (realized/unrealized)(2.2) (22.5)
Settlements(1.0) (0.7)
Ending balance, March 31
($14.0) 
($24.6)
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at March 31
($2.1) 
($22.3)

(a)Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for doubtful accounts associated with the receivables sold and cash amounts received from the receivables sold.


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Commodity Contracts - The fair value of electric, natural gas, coal and diesel fuel commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions):
 Alliant Energy IPL WPL
 Excluding FTRs FTRs Excluding FTRs FTRs Excluding FTRs FTRs
September 30, 2017
($22.2) 
$18.5
 
($10.4) 
$15.7
 
($11.8) 
$2.8
December 31, 2016(2.3) 11.0
 0.1
 10.0
 (2.4) 1.0
 Alliant Energy IPL WPL
 Excluding FTRs FTRs Excluding FTRs FTRs Excluding FTRs FTRs
March 31, 2018
($34.6) 
$5.2
 
($20.0) 
$4.6
 
($14.6) 
$0.6
December 31, 2017(23.5) 11.3
 (11.5) 10.1
 (12.0) 1.2

NOTE 11.12. DERIVATIVE INSTRUMENTS
Commodity Derivatives -
Notional Amounts - As of September 30, 2017,March 31, 2018, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts FTRs, coal contracts and diesel fuel contractsFTRs that were accounted for as commodity derivative instruments were as follows (units in thousands):
Electricity FTRs Natural Gas Coal Diesel FuelElectricity FTRs Natural Gas Coal Diesel Fuel
MWhs Years MWhs Years Dths Years Tons Years Gallons YearsMWhs Years MWhs Years Dths Years Tons Years Gallons Years
Alliant Energy1,645
 2017-2018 14,745
 2017-2018 173,234
 2017-2026 4,963
 2017-2019 7,308
 2017-2019990
 2018 3,370
 2018 156,074
 2018-2026 7,144
 2018-2020 5,670
 2018-2019
IPL—
 — 9,219
 2017-2018 79,561
 2017-2026 1,820
 2017-2019 —
 ——
 — 2,252
 2018 65,541
 2018-2026 2,975
 2018-2020 —
 —
WPL1,645
 2017-2018 5,526
 2017-2018 93,673
 2017-2026 3,143
 2017-2018 7,308
 2017-2019990
 2018 1,118
 2018 90,533
 2018-2026 4,169
 2018-2020 5,670
 2018-2019

Financial Statement Presentation - Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities. The fair values of current derivative assets are included in “Other current assets,” non-current derivative assets are included in “Deferred charges and other,” current derivative liabilities are included in “Other current liabilities” and non-current derivative liabilities are included in “Other liabilities” on the balance sheets as follows (in millions):
Alliant Energy IPL WPLAlliant Energy IPL WPL
September 30,
2017		 December 31,
2016		 September 30,
2017		 December 31,
2016		 September 30,
2017		 December 31,
2016		March 31,
2018		 December 31,
2017		 March 31,
2018		 December 31,
2017		 March 31,
2018		 December 31,
2017
Current derivative assets
$26.7
 
$29.4
 
$20.3
 
$19.1
 
$6.4
 
$10.3

$10.8
 
$21.1
 
$7.0
 
$15.8
 
$3.8
 
$5.3
Non-current derivative assets2.7
 12.0
 0.8
 1.7
 1.9
 10.3
3.3
 4.0
 0.9
 1.3
 2.4
 2.7
Current derivative liabilities18.5
 13.3
 4.6
 2.7
 13.9
 10.6
15.9
 18.7
 4.8
 5.0
 11.1
 13.7
Non-current derivative liabilities26.6
 15.3
 14.1
 5.6
 12.5
 9.7
30.8
 23.0
 19.9
 14.4
 10.9
 8.6


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Credit Risk-related Contingent Features - Various agreements contain credit risk-related contingent features, including requirements to maintain certain credit ratings and/or limitations on liability positions under the agreements based on credit ratings. Certain of these agreements with credit risk-related contingency features are accounted for as derivative instruments. In the event of a material change in creditworthiness or if liability positions exceed certain contractual limits, credit support may need to be provided in the form of letters of credit or cash collateral up to the amount of exposure under the contracts, or the contracts may need to be unwound and underlying liability positions paid. At September 30, 2017March 31, 2018 and December 31, 2016,2017, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a net liability position was not materially different than amounts that would be required to be posted as credit support to counterparties by Alliant Energy, IPL or WPL if the most restrictive credit risk-related contingent features for derivative agreements in a net liability position were triggered.

Balance Sheet Offsetting - The fair value amounts of derivative instruments subject to a master netting arrangement are not netted by counterparty on the balance sheets. However, if the fair value amounts of derivative instruments by counterparty were netted, amounts would not be materially different from gross amounts of derivative assets and derivative liabilities at September 30, 2017March 31, 2018 and December 31, 2016.2017. Fair value amounts recognized for the right to reclaim cash collateral (receivable) or the obligation to return cash collateral (payable) are not offset against fair value amounts recognized for derivative instruments executed with the same counterparty under the same master netting arrangement.

NOTE 12.13. COMMITMENTS AND CONTINGENCIES
NOTE 12(a)13(a) Capital Purchase Obligations - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects. IPL’s projects include the expansion of wind generation and installation of an SCR system at Ottumwa Unit 1 to reduce NOx emissions at the EGU. WPL’s projects include West Riverside. At September 30, 2017,March 31, 2018, Alliant Energy’s, IPL’s and WPL’s minimum future commitments related to certain contractual obligations for these projects were $105$95 million, $8$12 million and $97$83 million, respectively.


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NOTE 12(b)13(b) Other Purchase Obligations - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. In addition, there are various purchase obligations associated with other goods and services. At September 30, 2017,March 31, 2018, minimum future commitments related to these purchase obligations were as follows (in millions):
Alliant Energy IPL WPLAlliant Energy IPL WPL
Purchased power (a)
$1,278
 
$1,194
 
$84

$1,175
 
$1,127
 
$48
Natural gas847
 422
 425
892
 362
 530
Coal (b)144
 66
 78
165
 88
 77
Other (c)34
 25
 1
46
 26
 6

$2,303
 
$1,707
 
$588

$2,278
 
$1,603
 
$661

(a)Includes payments required by purchased power agreements for capacity rights and minimum quantities of MWhs required to be purchased.
(b)
Corporate Services entered into system-wide coal contracts on behalf of IPL and WPL that include minimum future commitments. These commitments were assigned to IPL and WPL based on information available as of September 30, 2017March 31, 2018 regarding expected future usage, which is subject to change.
(c)
Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2017March 31, 2018.

NOTE 12(c)13(c) Legal Proceedings -
Flood Damage Claims - In 2013, several plaintiffs purporting to represent a class of residential and commercial property owners filed a complaint against Cedar Rapids and Iowa City Railway Company (CRANDIC), Alliant Energy and various other defendants in the Iowa District Court for Linn County. Plaintiffs assert claims of negligence and strict liability based on their allegations that CRANDIC (along with other defendants) caused or exacerbated flooding of the Cedar River in June 2008. In February 2016, the Iowa District Court for Linn County ruled in favor of Alliant Energy and CRANDIC and dismissed all claims against them, resulting in no loss. In August 2016, the Iowa District Court for Linn County dismissed all claims against the remaining defendants. In September 2016, plaintiffs filed a notice of appeal with the Supreme Court of Iowa. Alliant Energy does not currently believe any material losses for this complaint are both probable and reasonably estimated, and therefore has not recognized any material loss contingency amounts as of September 30, 2017.March 31, 2018.


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NOTE 12(d)13(d) Guarantees and Indemnifications -
RMT - In 2013, Alliant Energy sold RMT. RMT provided renewable energy services, including construction and high voltage connection services for wind and solar projects. As part of the sale, Alliant Energy indemnified the buyer for any claims, including claims of warranty under the project obligations that were commenced or are based on actions that occurred prior to the sale, except for liabilities already accounted for through adjustments to the purchase price. Alliant Energy also guaranteed RMT’s performance obligations related to certain of RMT’s projects that were commenced prior to Alliant Energy’s sale of RMT. In the first quarter of 2017, all warranty periods and performance guarantees expired and all outstanding warranty claims were resolved.

Whiting Petroleum - In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum. Whiting Petroleum is an independent oil and gas company. Alliant Energy Resources, LLC, as the successor to a predecessor entity that owned Whiting Petroleum, and a wholly-owned subsidiary of AEF, continues to guarantee the partnership obligations of an affiliate of Whiting Petroleum under general partnership agreements in the oil and gas industry, including with respect to the future abandonment of certain platforms off the coast of California and related onshore plant and equipment owned by the partnerships. The guarantees do not include a maximum limit. As of September 30, 2017March 31, 2018, the present value of the abandonment obligations is estimated at $33$34 million. Alliant Energy is not aware of any material liabilities related to these guarantees of which it is probable that Alliant Energy Resources, LLC will be obligated to pay and therefore has not recognized any material liabilities related to this guarantee as of September 30, 2017.March 31, 2018.

Non-regulatedNon-utility Wind InvestmentFarm in Oklahoma - In July 2017, a wholly-owned subsidiary of AEF acquired a cash equity ownership interest in a non-regulatednon-utility wind farm located in Oklahoma. The wind farm provides electricity to a third-party under a long-term purchased power agreement. Alliant Energy provided a parent guarantee of its subsidiary’s indemnification obligations under the related operating agreement and purchased power agreement. Alliant Energy’s obligations under the operating agreement were $98 million as of September 30, 2017March 31, 2018 and will reduce annually until expiring in July 2047. Alliant Energy’s obligations under the purchased power agreement are subject to a maximum limit of $17 million and expire in December 2031, subject to potential extension. Alliant Energy is not aware of any material liabilities related to this guarantee that it is probable that it will be obligated to pay and therefore has not recognized any material

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liabilities related to this guarantee as of September 30, 2017. Refer to Note 5(a) for further discussion of the non-regulated wind investment.March 31, 2018.

IPL’s Minnesota Electric Distribution Assets - IPL provided indemnifications associated with the July 2015 sale of its Minnesota electric distribution assets for losses resulting from potential breach of IPL’s representations, warranties and obligations under the sale agreement. Alliant Energy and IPL believe the likelihood of having to make any material cash payments under these indemnifications is remote. IPL has not recorded any material liabilities related to these indemnifications as of September 30, 2017.March 31, 2018. The general terms of the indemnifications provided by IPL included a maximum limit of $17 million and expire in October 2020.

NOTE 12(e)13(e) Environmental Matters -
Manufactured Gas Plant (MGP) Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring costs. IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment.

Environmental liabilities related to the MGP sites are recorded based upon periodic studies. Such amounts are based on the best current estimate of the remaining amount to be incurred for investigation, remediation and monitoring costs for those sites where the investigation process has been or is substantially completed, and the minimum of the estimated cost range for those sites where the investigation is in its earlier stages. There are inherent uncertainties associated with the estimated remaining costs for MGP projects primarily due to unknown site conditions and potential changes in regulatory agency requirements. It is possible that future cost estimates will be greater than current estimates as the investigation process proceeds and as additional facts become known. Costs of future expenditures for environmental remediation obligations are not discounted. At September 30, 2017March 31, 2018, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions). At September 30, 2017,March 31, 2018, such amounts for WPL were not material.
Alliant Energy IPLAlliant Energy IPL
Range of estimated future costs
$12
-$31 
$10
-$27
$11
-$30 
$9
-$25
Current and non-current environmental liabilities16 1416 13

WPL Consent Decree - In 2013, the U.S. District Court for the Western District of Wisconsin approved a Consent Decree that WPL, along with the other owners of Edgewater and Columbia, entered into with the EPA and the Sierra Club, thereby resolving claims against WPL. Such claims included allegations that the owners of Edgewater, Nelson Dewey and Columbia violated the Prevention of Significant Deterioration program requirements, Title V Operating Permit requirements of the Clean Air Act (CAA) and the Wisconsin State Implementation Plan designed to implement the CAA.

WPL has completed various requirements under the Consent Decree. WPL’s remaining requirements include installing an SCR system at Columbia Unit 2 and fuel switching or retiring Edgewater Unit 4 by December 31, 2018. The Consent Decree also establishes SO2,sulfur dioxide (SO2), NOx and particulate matter emission rate limits for Columbia Units 1 and 2, and Edgewater Units 4 and 5. In addition, the Consent Decree includes annual plant-wide SO2 and NOx emission caps for Columbia and Edgewater. WPL is also in the process of completing approximately $7 million in environmental mitigation projects. Alliant Energy and WPL currently expect to recover material costs incurred by WPL related to compliance with the terms of the Consent Decree from WPL’s electric customers.


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IPL Consent Decree - In 2015, the U.S. District Court for the Northern District of Iowa approved a Consent Decree that IPL entered into with the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa, thereby resolving potential CAA issues associated with emissions from IPL’s coal-fired generating facilities in Iowa. IPL has completed various requirements under the Consent Decree. IPL’s remaining requirements include installing an SCR system or equivalent NOx reduction system at Ottumwa by December 31, 2019;2019, and fuel switching or retiring Prairie Creek Unit 4 by June 1, 2018, Burlington by December 31, 2021 and Prairie Creek Units 1 and 3 by December 31, 2025.

The Consent Decree also establishes SO2, NOx and particulate matter emission rate limits with varying averaging times for Burlington, Lansing, M.L. Kapp, Ottumwa and Prairie Creek. In addition, the Consent Decree includes calendar-year SO2 and NOx emission caps for Prairie Creek, and calendar-year SO2 and NOx emission caps in aggregate for Burlington, Dubuque, Lansing, M.L. Kapp, Ottumwa and Prairie Creek and Sutherland. IPL is also in the process of completing approximately $6 million in environmental mitigation projects.Creek. Alliant Energy and IPL currently expect to recover material

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costs incurred by IPL related to compliance with the environmental control systems and environmental mitigation projectsterms of the Consent Decree from IPL’s electric customers.

Other Environmental Contingencies - In addition to the environmental liabilities discussed above, various environmental rules are monitored that may have a significant impact on future operations. Several of these environmental rules are subject to legal challenges, reconsideration and/or other uncertainties. Given uncertainties regarding the outcome, timing and compliance plans for these environmental matters, the complete financial impact of each of these rules is not able to be determined; however future capital investments and/or modifications to EGUs to comply with certain of these rules could be significant. Specific current, proposed or potential environmental matters include, among others: Cross-State Air Pollution Rule, Effluent Limitation Guidelines, Coal Combustion Residuals Rule, and various legislation and EPA regulations to monitor and regulate the emission of greenhouse gases, including carbon emissions from new (CAA Section 111(b)) and existing (CAA Section 111(d)) fossil-fueled EGUs.

NOTE 13.14. SEGMENTS OF BUSINESS
In the fourth quarter of 2017, Alliant Energy and WPL modified the segment reporting related to ATC Holdings, consistent with information used by their chief operating decision maker to evaluate performance and allocate resources. As of December 31, 2017, ATC Holdings are no longer included in Alliant Energy’s utility electric operations reportable segment or WPL’s electric operations reportable segment. As a result, all prior period amounts impacted by this change were reclassified to conform to the new presentation. Alliant Energy’s related amounts were reclassified from “Electric Utility” to “ATC Holdings, Non-Utility, Parent and Other” in the table below. There was no resulting change to WPL’s segment reporting for the three months ended March 31, 2017.

Alliant Energy - Certain financial information relating to Alliant Energy’s business segments is as follows. Intersegment revenues were not material to Alliant Energy’s operations. Refer to Note 5(a) for discussion of Alliant Energy’s acquisition of an interest in a non-regulated wind farm in Oklahoma in July 2017, which increased the assets for “Non-Regulated, Parent and Other.” Refer to Note 3 for discussion of asset valuation charges recorded in the third quarter of 2016 related to the Franklin County wind farm.
 Utility (a) Non-Regulated, Alliant Energy
 Electric Gas Other Total Parent and Other Consolidated
 (in millions)
Three Months Ended September 30, 2017           
Operating revenues
$840.6
 
$45.8
 
$11.2
 
$897.6
 
$9.3
 
$906.9
Operating income (loss)232.6
 (2.4) (7.7) 222.5
 9.0
 231.5
Net income (loss) attributable to Alliant Energy common shareowners      176.3
 (7.5) 168.8
Three Months Ended September 30, 2016           
Operating revenues
$864.3
 
$39.5
 
$9.4
 
$913.2
 
$11.4
 
$924.6
Operating income (loss)244.2
 (3.7) 0.4
 240.9
 (78.3) 162.6
Amounts attributable to Alliant Energy common shareowners:           
Income (loss) from continuing operations, net of tax      183.1
 (54.3) 128.8
Loss from discontinued operations, net of tax      —
 (0.4) (0.4)
Net income (loss)      183.1
 (54.7) 128.4
 Utility (a) Non-Regulated, Alliant Energy
 Electric Gas Other Total Parent and Other Consolidated
 (in millions)
Nine Months Ended September 30, 2017           
Operating revenues
$2,199.1
 
$262.7
 
$34.4
 
$2,496.2
 
$29.9
 
$2,526.1
Operating income (loss)475.4
 29.5
 (6.8) 498.1
 25.6
 523.7
Amounts attributable to Alliant Energy common shareowners:           
Income from continuing operations, net of tax      353.5
 8.6
 362.1
Income from discontinued operations, net of tax      —
 1.4
 1.4
Net income      353.5
 10.0
 363.5
Nine Months Ended September 30, 2016           
Operating revenues
$2,209.1
 
$248.7
 
$35.0
 
$2,492.8
 
$30.2
 
$2,523.0
Operating income (loss)473.3
 27.0
 4.4
 504.7
 (67.6) 437.1
Amounts attributable to Alliant Energy common shareowners:           
Income (loss) from continuing operations, net of tax      350.3
 (39.5) 310.8
Loss from discontinued operations, net of tax      —
 (2.0) (2.0)
Net income (loss)      350.3
 (41.5) 308.8
         ATC Holdings,  
 Utility Non-Utility, Alliant Energy
 Electric Gas Other Total Parent and Other Consolidated
 (in millions)
Three Months Ended March 31, 2018           
Revenues
$708.7
 
$185.6
 
$13.2
 
$907.5
 
$8.8
 
$916.3
Operating income126.7
 31.5
 1.4
 159.6
 6.1
 165.7
Net income attributable to Alliant Energy common shareowners      100.7
 20.2
 120.9
Three Months Ended March 31, 2017           
Revenues
$677.6
 
$154.3
 
$11.7
 
$843.6
 
$10.3
 
$853.9
Operating income110.9
 28.6
 0.4
 139.9
 7.3
 147.2
Amounts attributable to Alliant Energy common shareowners:           
Income from continuing operations, net of tax      82.7
 16.3
 99.0
Income from discontinued operations, net of tax      —
 1.4
 1.4
Net income      82.7
 17.7
 100.4


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(a)Alliant Energy’s utility business segments include: a) utility electric operations, which include Alliant Energy’s entire investment in ATC; b) utility gas operations; and c) utility other, which includes steam operations and the unallocated portions of the utility business.

IPL - Certain financial information relating to IPL’s business segments is as follows. Intersegment revenues were not material to IPL’s operations.
 Electric Gas Other Total
 (in millions)
Three Months Ended September 30, 2017       
Operating revenues
$489.0
 
$27.4
 
$11.0
 
$527.4
Operating income (loss)138.3
 (2.1) (4.4) 131.8
Earnings available for common stock      120.4
Three Months Ended September 30, 2016       
Operating revenues
$483.2
 
$23.9
 
$9.1
 
$516.2
Operating income (loss)125.9
 (1.4) 1.4
 125.9
Earnings available for common stock      114.1
Nine Months Ended September 30, 2017       
Operating revenues
$1,217.6
 
$147.2
 
$33.3
 
$1,398.1
Operating income (loss)234.5
 14.7
 (1.5) 247.7
Earnings available for common stock      200.4
Nine Months Ended September 30, 2016       
Operating revenues
$1,209.2
 
$142.6
 
$34.1
 
$1,385.9
Operating income213.8
 15.3
 6.8
 235.9
Earnings available for common stock      191.6
 Electric Gas Other Total
 (in millions)
Three Months Ended March 31, 2018       
Revenues
$405.7
 
$108.1
 
$12.0
 
$525.8
Operating income57.5
 16.9
 1.2
 75.6
Earnings available for common stock      46.7
Three Months Ended March 31, 2017       
Revenues
$356.2
 
$83.1
 
$11.2
 
$450.5
Operating income35.3
 14.6
 1.4
 51.3
Earnings available for common stock      37.2

WPL - Certain financial information relating to WPL’s business segments is as follows. Intersegment revenues were not material to WPL’s operations.
Electric Gas Other TotalElectric Gas Other Total
(in millions)(in millions)
Three Months Ended September 30, 2017       
Operating revenues
$351.6
 
$18.4
 
$0.2
 
$370.2
Three Months Ended March 31, 2018       
Revenues
$303.0
 
$77.5
 
$1.2
 
$381.7
Operating income69.2
 14.6
 0.2
 84.0
Earnings available for common stock      54.0
Three Months Ended March 31, 2017       
Revenues
$321.4
 
$71.2
 
$0.5
 
$393.1
Operating income (loss)94.3
 (0.3) (3.3) 90.7
75.6
 14.0
 (1.0) 88.6
Earnings available for common stock      49.8
      45.5
Three Months Ended September 30, 2016       
Operating revenues
$381.1
 
$15.6
 
$0.3
 
$397.0
Operating income (loss)118.3
 (2.3) (1.0) 115.0
Earnings available for common stock      69.0
Nine Months Ended September 30, 2017       
Operating revenues
$981.5
 
$115.5
 
$1.1
 
$1,098.1
Operating income (loss)240.9
 14.8
 (5.3) 250.4
Earnings available for common stock      133.4
Nine Months Ended September 30, 2016       
Operating revenues
$999.9
 
$106.1
 
$0.9
 
$1,106.9
Operating income (loss)259.5
 11.7
 (2.4) 268.8
Earnings available for common stock      158.7

NOTE 14.15. RELATED PARTIES
Service Agreements - Pursuant to service agreements, IPL and WPL receive various administrative and general services from an affiliate, Corporate Services. These services are billed to IPL and WPL at cost based on expenses incurred by Corporate Services for the benefit of IPL and WPL, respectively. These costs consisted primarily of employee compensation and benefits, fees associated with various professional services, depreciation and amortization of property, plant and equipment, and a return on net assets. Corporate Services also acts as agent on behalf of IPL and WPL pursuant to the service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases among IPL and WPL based on statements received from MISO. The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30March 31 were as follows (in millions):

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IPL WPL
Three Months Nine Months Three Months Nine MonthsIPL WPL
2017 2016 2017 2016 2017 2016 2017 20162018 2017 2018 2017
Corporate Services billings
$48
 
$41
 
$130
 
$124
 
$37
 
$33
 
$100
 
$103

$41
 
$39
 
$33
 
$31
Sales credited8
 4
 15
 7
 6
 3
 8
 6
5
 2
 1
 —
Purchases billed109
 126
 271
 324
 32
 23
 99
 65
93
 66
 17
 34

Net intercompany payables to Corporate Services were as follows (in millions):
 IPL WPL
 September 30, 2017 December 31, 2016 September 30, 2017 December 31, 2016
Net payables to Corporate Services$118 $104 $64 $72
 IPL WPL
 March 31, 2018 December 31, 2017 March 31, 2018 December 31, 2017
Net payables to Corporate Services$96 $114 $64 $61

ATC LLC - Pursuant to various agreements, WPL receives a range of transmission services from ATC LLC.ATC. WPL provides operation, maintenance, and construction services to ATC LLC.ATC. WPL and ATC LLC also bill each other for use of shared facilities owned by each party. The related amounts billed between the parties for the three and nine months ended September 30March 31 were as follows (in millions):
 Three Months Nine Months
 2017 2016 2017 2016
ATC LLC billings to WPL
$26
 
$28
 
$79
 
$82
WPL billings to ATC LLC2
 4
 8
 10
 2018 2017
ATC billings to WPL
$27
 
$26
WPL billings to ATC2
 3

WPL owed ATC LLC net amounts of $8$7 million as of September 30, 2017March 31, 2018 and $89 million as of December 31, 20162017.

Refer to
26
Note 5(a) for discussion
Table of WPL’s transfer of its investment in ATC LLC to ATI on December 31, 2016.Contents

Franklin County Wind Farm - Refer to Note 3 for discussion of the transfer of the Franklin County wind farm from AEF to IPL in April 2017.

ITEM 2. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

This MDA includes information relating to Alliant Energy, IPL and WPL, as well as AEF and Corporate Services. Where appropriate, information relating to a specific entity has been segregated and labeled as such. The following discussion and analysis should be read in conjunction with the Financial Statements and the Notes included in this report, as well as the financial statements, notes and MDA included in the 20162017 Form 10-K. Unless otherwise noted, all “per share” references in MDA refer to earnings per diluted share.

EXECUTIVE OVERVIEW

Description of Business
General - Alliant Energy is a Midwest U.S. energy holding company whose primary subsidiaries are IPL, WPL, AEF and Corporate Services. IPL and WPL are public utilities, and AEF is the parent company for Alliant Energy’s non-regulatednon-utility businesses, including Alliant Energy’s Transportation business and certain non-utility generation holdings, and holds all of Alliant Energy’s investment in ATC.ATC Holdings. Corporate Services provides administrative services to Alliant Energy and its subsidiaries. An illustration of Alliant Energy’s primary businesses is shown below.
  Alliant Energy  
      
     
Utilities ATC Investment and Corporate Services Non-regulatedATC Holdings, Non-utility and Parent
 - Retail electric and gas services in IA (IPL)  - TransportationATC Holdings (AEF)
 - Retail electric and gas services in WI (WPL)  - Non-regulated wind investment (AEF)
 - ATC Investment (ATI) - Sheboygan Falls Energy FacilityTransportation (AEF)
 - Wholesale electric service in MN, IL & IA (IPL)  - Parent CompanyNon-utility wind farm (AEF)
 - Wholesale electric service in WI (WPL)  - Sheboygan Falls Energy Facility (AEF)
 - Corporate Services 
 - Parent Company


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Financial Results - Alliant Energy’s net income and EPSearnings per weighted average common share (EPS) attributable to Alliant Energy common shareowners for the thirdfirst quarter were as follows (dollars in millions, except per share amounts):
2017 20162018 2017
Income (Loss) EPS Income (Loss) EPSIncome EPS Income EPS
Continuing operations:              
Utilities, ATC Investment and Corporate Services
$179.7
 
$0.78
 
$186.7
 
$0.82
Non-regulated and Parent(10.9) (0.05) (57.9) (0.25)
Utilities and Corporate Services
$104.4
 
$0.45
 
$85.9
 
$0.38
ATC Holdings6.3
 0.03
 6.9
 0.03
Non-utility and Parent10.2
 0.04
 6.2
 0.02
Income from continuing operations168.8
 0.73
 128.8
 0.57
120.9
 0.52
 99.0
 0.43
Loss from discontinued operations—
 —
 (0.4) —
Income from discontinued operations—
 —
 1.4
 0.01
Net income
$168.8
 
$0.73
 
$128.4
 
$0.57

$120.9
 
$0.52
 
$100.4
 
$0.44

The table above includes EPS from continuing operations for utilities ATC Investment and Corporate Services, ATC Holdings, and non-regulatednon-utility and parent, which are non-GAAP financial measures. Alliant Energy believes these non-GAAP financial measures are useful to investors because they facilitate an understanding of segment performance and trends, and provide additional information about Alliant Energy’s operations on a basis consistent with the measures that management uses to manage its operations and evaluate its performance.

Alliant Energy’s, IPL’s and WPL’s income from continuing operations increased (decreased) by $40$22 million, $6$10 million and ($19)$9 million, respectively, for the three-month period. Alliant Energy’s increase was primarily due to asset valuation charges at AEF related to the Franklin County wind farm in the third quarter of 2016, higher revenuesmargins resulting from IPL’s interim retail electric base rate increase implemented in April 2017, and WPL’s retail electric and gas base rate increases implemented in January 2017, partially offset by estimated temperature impacts on IPL’s and WPL’shigher retail electric and gas sales due to colder temperatures in the first quarter of 2018 compared to the same period in 2017. These items were partially offset by higher depreciation expense, higher energy efficiency cost recovery amortization at WPL, and lower AFUDC at IPL. WPL’s decrease was also impacted by reduced equity income resulting from the transfer of WPL’s investment in ATC LLC to ATI on December 31, 2016.expense.

Refer to “Results of Operations” for additional details regarding the various factors impacting earnings during the thirdfirst quarters of 20172018 and 2016.2017.


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20172018 Overview - Alliant Energy, IPL and WPL continue to focus on achieving their financial objectives and executing their strategic plan. Key developments since the filing of the 20162017 Form 10-K include the following:
Marshalltown Generating Station - IPL’s construction of Marshalltown, an approximate 660 MW natural gas-fired combined-cycle EGU, was completed in April 2017. Final capital expenditures are currently estimated to be approximately $645 million to construct the EGU and a pipeline to supply natural gas to the EGU, excluding transmission network upgrades and AFUDC.
Franklin County Wind Farm - In April 2017, the 99 MW Franklin County wind farm was transferred from AEF to IPL.
•
IPL’s and WPL’s Potential Expansion of Wind Generation - In addition to IPL’s 500 MW expansion of wind generation approved by the IUB in October 2016 and transfer of the 99 MW Franklin County wind farm toApril 2018, IPL in 2017, IPL and WPL are currently exploring options to own and operate up to 500 MW and 200 MW, respectively, of additional new wind generation. In August 2017, IPL filed an application withreceived approval from the IUB for advance rate-making principles for the up tosecond 500 MW of the additional wind generation. In the fourth quarter of 2017, WPL expects to file for approval from the PSCW and FERC for the acquisition of 55 MW of the Forward Wind Energy Center, and plans to file for authority for the remaining up to 200 MW of new wind generation. In April 2018, WPL acquired 55 MW of FWEC, which is a 129 MW wind farm located in Wisconsin. Refer to “Strategic Overview” for further discussion. The amount and timing of these wind projects will largely depend on regulatory approvals and the acquisition of wind sites.
WPL’s Construction of West Riverside - In October 2017, WPL received an order from the PSCW authorizing various electric cooperatives, which currently have wholesale power supply agreements with WPL, to acquire approximately 65 MW of West Riverside while the EGU is being constructed. As part of the electric cooperatives’ acquisitions, which are currently expected to be completed in the fourth quarter of 2017, the current wholesale power supply agreements with the various electric cooperatives will be extended by at least four years until 2026 with automatic continuation of such agreements unless terminated by either party, with a five-year notice requirement.
•
Non-regulated Wind Investment in Oklahoma - In July 2017, a wholly-owned subsidiary of AEF acquired a 50% cash equity ownership interest in a 225 MW non-regulated wind farm located in Oklahoma. Refer to Note 5(a) for further discussion.
IPL’s Tax Reform Benefits - In April 2018, the IUB issued an order approving the return of approximately $35 million of estimated annual tax benefits for 2018 to IPL’s retail electric customers utilizing the tax benefit rider effective May 1, 2018, subject to true-up. The IUB order also approved the return of approximately $3 million of estimated annual tax benefits for 2018 to IPL’s retail gas customers utilizing interim rates to be implemented May 14, 2018 for IPL’s 2017 Test Year gas rate review, subject to further review by the IUB. Lastly, the IUB order determined the excess deferred taxes resulting from the remeasurement of accumulated deferred income taxes caused by Tax Reform (approximately $370 million revenue requirement) will be addressed in IPL’s next retail electric and gas rate reviews.
WPL’s Tax Reform Benefits - In April 2018, WPL received a decision from the PSCW directing WPL to return annual tax benefits for 2018 to WPL’s retail electric and gas customers, which WPL currently estimates to be approximately $43 million. The estimated tax benefits related to the first half of 2018 will be provided as a one-time credit on WPL’s retail electric and gas customers’ July 2018 bills. Thereafter, WPL currently expects to provide a monthly refund equal to one-twelfth of the estimated annual tax benefits for 2018 to its retail electric and gas customers through the end of 2018. The PSCW decision also determined the excess deferred taxes resulting from the remeasurement of accumulated deferred income taxes caused by Tax Reform (approximately $460 million revenue requirement) will be addressed in WPL’s next retail electric and gas rate review.
IPL’s Retail ElectricGas Rate Review (2016(2017 Test Year) - In April 2017,May 2018, IPL filed a request with the IUB to increase annual electricgas base rates for its Iowa retail electric customers.gas customers by $20 million, or approximately 8%. The request was based on a 20162017 historical Test Year as adjusted for certain known and measurable changes occurring up to 12 months after the commencement of the proceeding. The key drivers for the filing included recovery of capital projects, primarily power grid modernization and investments that

30
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advance cleaner energy, including Marshalltown.Tax Reform. An interim retail electric basegas rate increase of $102$11 million, or approximately 7%5%, on an annual basis, waswill be implemented effective April 13, 2017. In September 2017, IPL reached a partial, non-unanimous settlement agreement with the Iowa Office of Consumer Advocate, the Iowa Business Energy Coalition and the Large Energy Group to increase annual retail electric base rates by $130 million, or approximately 9%, subject to IUB approval. As a result of the proposed settlement, in the third quarter of 2017, IPL recorded a write-down of regulatory assets of $9 million.May 14, 2018. IPL currently expects to implementa decision from the IUB in 2019 with final rates in the first quarter of 2018.
WPL’s Retail Fuel-related Rate Filing (2018 Test Year) - In July 2017, WPL filed a request with the PSCW to increase annual rates for WPL’s retail electric customerseffective by $6 million, or approximately 1%, in 2018. The increase primarily reflects a change in expected fuel-related costs in 2018, which are expected to be offset by $3 million of over-collections from WPL’s 2016 fuel-related costs. Any rate changes granted from this request are expected to be effective January 1, 2018.
MISO Transmission Owner Return on Equity Complaints - A group of MISO cooperative and municipal utilities previously filed two complaints with FERC requesting a reduction to the base return on equity used by MISO transmission owners, including ITC and ATC LLC, to determine electric transmission costs billed to utilities, including IPL and WPL. In September 2016, FERC issued an order on the first complaint and established a base return on equity of 10.32%, excluding any incentive adders granted by FERC, effective September 28, 2016, and for the refund period from November 12, 2013 through February 11, 2015 (first complaint period). During the nine months ended September 30, 2017, Alliant Energy, IPL and WPL received the refunds for the first complaint period of $50 million, $39 million and $11 million, respectively, after final true-ups. Pursuant to IUB approval, IPL’s retail portion of the refund from ITC is currently being refunded to its retail customers in 2017. WPL’s retail portion of the refund from ATC LLC will remain in a regulatory liability until such refunds are approved to be returned to retail customers in a future rate proceeding.
Credit Facility Agreement - In August 2017, Alliant Energy, IPL and WPL entered into a single new credit facility agreement, which expires in August 2022. The new credit facility agreement includes financial covenants similar to those that were included in the previous credit facility agreements. As of September 30, 2017, the short-term borrowing capacity totaled $1 billion ($300 million for Alliant Energy at the parent company level, $300 million for IPL and $400 million for WPL).
At-the-Market Offering Program - In the second quarter of 2017, Alliant Energy issued 3.1 million shares of common stock through an at-the-market offering program and received cash proceeds of $124 million, net of $1 million in commissions and fees. The proceeds from the issuances of common stock were used for general corporate purposes.2019.

Future Developments - The following includes key items expected to impact Alliant Energy, IPL and WPL in the future that have been identified since the filing of the 2016 Form 10-K:

2018 Forecast - In 2018, the following financing activities, and impacts to results of operations, are currently anticipated to occur:
Financing Plans - Alliant Energy currently expects to issue up to $200 million of common stock in 2018 through one or more offerings and its Shareowner Direct Plan. IPL currently expects to issue up to $700 million of long-term debt securities in 2018, of which $350 million would be used to retire maturing long-term debt in 2018. AEF currently expects to issue up to $1.0 billion of long-term debt in 2018, of which $595 million would be used to refinance term loans.
Common Stock Dividends - Alliant Energy announced a 6% increase in its targeted 2018 annual common stock dividend to $1.34 per share, which is equivalent to a quarterly rate of $0.335 per share, beginning with the February 2018 dividend payment. The timing and amount of future dividends is subject to an approved dividend declaration from Alliant Energy’s Board of Directors, and is dependent upon earnings expectations, capital requirements, and general financial business conditions, among other factors.
•
Utility Electric and Gas Margins - Alliant Energy and IPL currently expect an increase in electric and gas margins in 2018 compared to 2017 as a result of base rate increases in effect from IPL’s retail electric rate review (2016 Test Year) and IPL’s planned retail gas rate review (2017 Test Year). Refer to “Rate Matters” for further discussion of these rate reviews, as well as “Other Future Considerations” for discussion of expected changes in Alliant Energy’s, IPL’s and WPL’s electric transmission service expense in 2018 compared to 2017.
Depreciation and Amortization Expenses - Alliant Energy and IPL currently expect an increase in depreciation and amortization expenses in 2018 compared to 2017 due to property additions, and the implementation of updated depreciation rates for IPL as a result of a recently completed depreciation study, which is expected to be effective with the implementation of final rates from IPL’s retail electric rate review (2016 Test Year).
Interest Expense - Alliant Energy currently expects interest expense to increase in 2018 compared to 2017 due to financings completed in 2017 and planned in 2018 as discussed above.
AFUDC - Alliant Energy currently expects AFUDC to increase in 2018 compared to 2017 primarily due to increased construction work in progress balances related to IPL’s expansion of wind generation and WPL’s West Riverside facility.

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RESULTS OF OPERATIONS

Overview - “Executive Overview” provides an overview of Alliant Energy’s, IPL’s and WPL’s earnings for the three months ended September 30, 2017March 31, 2018 and 2016.2017. Additional earnings details for the three and nine months ended September 30,March 31, 2018 and 2017 and 2016 are discussed below.

Results of operations include financial information prepared in accordance with GAAP as well as utility electric margins and utility gas margins, which are not measures of financial performance under GAAP. Utility electric margins are defined as electric operating revenues less electric production fuel, purchased power and electric transmission service expenses. Utility gas margins are defined as gas operating revenues less cost of gas sold. Utility electric margins and utility gas margins are non-GAAP financial measures because they exclude other utility and non-regulated operatingnon-utility revenues, other operation and maintenance expenses, depreciation and amortization expenses, and taxes other than income tax expense.

Management believes that utility electric and gas margins provide a meaningful basis for evaluating and managing utility operations since electric production fuel, purchased power and electric transmission service expenses and cost of gas sold are generally passed through to customers, and therefore, result in changes to electric and gas operating revenues that are comparable to changes in such expenses. The presentation of utility electric and gas margins herein is intended to provide supplemental information for investors regarding operating performance. These utility electric and gas margins may not be comparable to how other entities define utility electric and gas margin. Furthermore, these measures are not intended to replace operating income as determined in accordance with GAAP as an indicator of operating performance.


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For the three and nine months ended September 30,March 31, operating income and a reconciliation of utility electric and gas margins to the most directly comparable GAAP measure, operating income, was as follows (in millions):
 Alliant Energy IPL WPL
 Three Months Nine Months Three Months Nine Months Three Months Nine Months
 2017 2016 2017 2016 2017 2016 2017 2016 2017 2016 2017 2016
Operating income
$231.5
 
$162.6
 
$523.7
 
$437.1
 
$131.8
 
$125.9
 
$247.7
 
$235.9
 
$90.7
 
$115.0
 
$250.4
 
$268.8
 Alliant Energy IPL WPL
Three Months2017 2016 2017 2016 2017 2016
Electric utility operating revenues
$840.6
 
$864.3
 
$489.0
 
$483.2
 
$351.6
 
$381.1
Electric production fuel and purchased power expenses(222.6) (245.9) (122.5) (125.0) (100.1) (120.9)
Electric transmission service expense(121.0) (138.6) (78.2) (95.9) (42.8) (42.7)
Utility Electric Margin (non-GAAP)497.0
 479.8
 288.3
 262.3
 208.7
 217.5
            
Gas utility operating revenues45.8
 39.5
 27.4
 23.9
 18.4
 15.6
Cost of gas sold(15.0) (12.5) (9.9) (8.0) (5.1) (4.5)
Utility Gas Margin (non-GAAP)30.8
 27.0
 17.5
 15.9
 13.3
 11.1
            
Other utility operating revenues11.2
 9.4
 11.0
 9.1
 0.2
 0.3
Non-regulated operating revenues9.3
 11.4
 —
 —
 —
 —
Asset valuation charges for Franklin County wind farm—
 (86.4) —
 —
 —
 —
Other operation and maintenance expenses(169.1) (148.6) (104.4) (94.8) (66.1) (54.2)
Depreciation and amortization expenses(120.7) (104.1) (66.2) (52.7) (53.6) (48.7)
Taxes other than income tax expense(27.0) (25.9) (14.4) (13.9) (11.8) (11.0)
Operating income
$231.5
 
$162.6
 
$131.8
 
$125.9
 
$90.7
 
$115.0

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Alliant Energy IPL WPLAlliant Energy IPL WPL
Nine Months2017 2016 2017 2016 2017 2016
Electric utility operating revenues
$2,199.1
 
$2,209.1
 
$1,217.6
 
$1,209.2
 
$981.5
 
$999.9
Three Months2018 2017 2018 2017 2018 2017
Operating income
$165.7
 
$147.2
 
$75.6
 
$51.3
 
$84.0
 
$88.6
           
Electric utility revenues
$708.7
 
$677.6
 
$405.7
 
$356.2
 
$303.0
 
$321.4
Electric production fuel and purchased power expenses(614.7) (646.3) (330.0) (324.8) (284.7) (321.5)(203.2) (207.8) (114.6) (109.5) (88.6) (98.3)
Electric transmission service expense(363.3) (396.8) (235.0) (270.7) (128.3) (126.1)(126.4) (124.7) (90.8) (81.7) (35.6) (43.0)
Utility Electric Margin (non-GAAP)1,221.1
 1,166.0
 652.6
 613.7
 568.5
 552.3
379.1
 345.1
 200.3
 165.0
 178.8
 180.1
                      
Gas utility operating revenues262.7
 248.7
 147.2
 142.6
 115.5
 106.1
Gas utility revenues185.6
 154.3
 108.1
 83.1
 77.5
 71.2
Cost of gas sold(135.5) (132.3) (74.6) (76.3) (60.9) (56.0)(111.2) (92.2) (60.6) (47.8) (50.6) (44.4)
Utility Gas Margin (non-GAAP)127.2
 116.4
 72.6
 66.3
 54.6
 50.1
74.4
 62.1
 47.5
 35.3
 26.9
 26.8
                      
Other utility operating revenues34.4
 35.0
 33.3
 34.1
 1.1
 0.9
Non-regulated operating revenues29.9
 30.2
 —
 —
 —
 —
Asset valuation charges for Franklin County wind farm—
 (86.4) —
 —
 —
 —
Other utility revenues13.2
 11.7
 12.0
 11.2
 1.2
 0.5
Non-utility revenues8.8
 10.3
 —
 —
 —
 —
Other operation and maintenance expenses(467.1) (438.2) (288.7) (279.8) (179.7) (157.2)(162.4) (148.6) (105.5) (93.2) (56.3) (54.4)
Depreciation and amortization expenses(342.7) (308.7) (181.0) (157.8) (158.8) (143.5)(120.4) (107.0) (64.8) (53.6) (54.6) (52.4)
Taxes other than income tax expense(79.1) (77.2) (41.1) (40.6) (35.3) (33.8)(27.0) (26.4) (13.9) (13.4) (12.0) (12.0)
Operating income
$523.7
 
$437.1
 
$247.7
 
$235.9
 
$250.4
 
$268.8

$165.7
 
$147.2
 
$75.6
 
$51.3
 
$84.0
 
$88.6

Operating Income Variances - Variances between periods in operating income for the three and nine months ended September 30, 2017March 31, 2018 compared to the same periodsperiod in 20162017 were as follows (in millions):
 Three Months Nine Months
 Alliant Energy IPL WPL Alliant Energy IPL WPL
Asset valuation charges for Franklin County wind farm in 2016 (refer to Note 3 for details)

$86
 
$—
 
$—
 
$86
 
$—
 
$—
Total utility electric margin variance (refer to details below)17
 26
 (9) 55
 39
 16
Total utility gas margin variance (refer to details below)4
 2
 2
 11
 6
 5
Total other operation and maintenance expenses variance (refer to details below)(21) (10) (12) (29) (9) (23)
Higher depreciation expense primarily due to additional plant in service in 2017, including impacts from Marshalltown(9) (9) (2) (20) (18) (6)
Higher depreciation expense at WPL due to updated depreciation rates effective January 2017 approved by the PSCW and FERC(3) —
 (3) (9) —
 (9)
Higher depreciation expense at IPL due to write-down of regulatory assets resulting from the proposed IPL electric rate review settlement in 2017(5) (5) —
 (5) (5) —
Other—
 2
 —
 (2) (1) (1)
 
$69
 
$6
 
($24) 
$87
 
$12
 
($18)
 Alliant Energy IPL WPL
Total higher (lower) utility electric margin variance (refer to details below)
$34
 
$35
 
($1)
Total higher utility gas margin variance (refer to details below)12
 12
 —
Total higher other operation and maintenance expenses variance (refer to details below)(14) (12) (2)
Total higher depreciation and amortization expense, primarily due to additional plant in service in 2017, including impacts from the Marshalltown Generating Station(13) (11) (2)
 
$19
 
$24
 
($5)

Electric and Gas Revenues and Sales Summary - Electric and gas revenues (in millions), and MWh and Dth sales (in thousands), for the three and nine months ended September 30March 31 were as follows:
Alliant EnergyElectric GasElectric Gas
Revenues MWhs Sold Revenues Dths SoldRevenues MWhs Sold Revenues Dths Sold
2017 2016 2017 2016 2017 2016 2017 20162018 2017 2018 2017 2018 2017 2018 2017
Three Months               
Retail
$745.7
 
$772.5
 6,722
 6,935
 
$37.4
 
$30.9
 3,744
 3,926

$635.3
 
$601.9
 6,336
 6,193
 
$173.4
 
$144.5
 23,848
 20,560
Sales for resale75.6
 77.5
 1,390
 1,271
 —
 —
 —
 —
60.6
 64.4
 1,121
 1,051
 —
 —
 —
 —
Transportation/Other19.3
 14.3
 22
 24
 8.4
 8.6
 19,787
 20,302
12.8
 11.3
 26
 26
 12.2
 9.8
 24,061
 19,108

$840.6
 
$864.3
 8,134
 8,230
 
$45.8
 
$39.5
 23,531
 24,228

$708.7
 
$677.6
 7,483
 7,270
 
$185.6
 
$154.3
 47,909
 39,668
Nine Months               
Retail
$1,950.4
 
$1,970.4
 18,851
 19,139
 
$236.9
 
$222.9
 30,971
 32,720
Sales for resale204.8
 204.9
 3,564
 3,372
 —
 —
 —
 —
Transportation/Other43.9
 33.8
 72
 75
 25.8
 25.8
 54,849
 61,615

$2,199.1
 
$2,209.1
 22,487
 22,586
 
$262.7
 
$248.7
 85,820
 94,335
IPLElectric Gas
 Revenues MWhs Sold Revenues Dths Sold
 2018 2017 2018 2017 2018 2017 2018 2017
Retail
$368.6
 
$326.7
 3,669
 3,553
 
$99.8
 
$76.5
 12,692
 10,792
Sales for resale29.7
 22.3
 527
 350
 —
 —
 —
 —
Transportation/Other7.4
 7.2
 9
 10
 8.3
 6.6
 11,223
 10,740
 
$405.7
 
$356.2
 4,205
 3,913
 
$108.1
 
$83.1
 23,915
 21,532
WPLElectric Gas
 Revenues MWhs Sold Revenues Dths Sold
 2018 2017 2018 2017 2018 2017 2018 2017
Retail
$266.7
 
$275.2
 2,667
 2,640
 
$73.6
 
$68.0
 11,156
 9,768
Sales for resale30.9
 42.1
 594
 701
 —
 —
 —
 —
Transportation/Other5.4
 4.1
 17
 16
 3.9
 3.2
 12,838
 8,368
 
$303.0
 
$321.4
 3,278
 3,357
 
$77.5
 
$71.2
 23,994
 18,136


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IPLElectric Gas
 Revenues MWhs Sold Revenues Dths Sold
 2017 2016 2017 2016 2017 2016 2017 2016
Three Months               
Retail
$443.3
 
$443.7
 3,784
 3,898
 
$22.0
 
$18.9
 2,189
 2,486
Sales for resale33.6
 29.5
 692
 389
 —
 —
 —
 —
Transportation/Other12.1
 10.0
 9
 11
 5.4
 5.0
 9,374
 8,783
 
$489.0
 
$483.2
 4,485
 4,298
 
$27.4
 
$23.9
 11,563
 11,269
Nine Months               
Retail
$1,105.5
 
$1,110.8
 10,761
 10,944
 
$129.9
 
$127.2
 16,548
 18,097
Sales for resale83.5
 75.5
 1,527
 1,056
 —
 —
 —
 —
Transportation/Other28.6
 22.9
 30
 31
 17.3
 15.4
 29,092
 27,066
 
$1,217.6
 
$1,209.2
 12,318
 12,031
 
$147.2
 
$142.6
 45,640
 45,163
WPLElectric Gas
 Revenues MWhs Sold Revenues Dths Sold
 2017 2016 2017 2016 2017 2016 2017 2016
Three Months               
Retail
$302.4
 
$328.8
 2,938
 3,037
 
$15.4
 
$12.0
 1,555
 1,440
Sales for resale42.0
 48.0
 698
 882
 —
 —
 —
 —
Transportation/Other7.2
 4.3
 13
 13
 3.0
 3.6
 10,413
 11,519
 
$351.6
 
$381.1
 3,649
 3,932
 
$18.4
 
$15.6
 11,968
 12,959
Nine Months               
Retail
$844.9
 
$859.6
 8,090
 8,195
 
$107.0
 
$95.7
 14,423
 14,623
Sales for resale121.3
 129.4
 2,037
 2,316
 —
 —
 —
 —
Transportation/Other15.3
 10.9
 42
 44
 8.5
 
$10.4
 25,757
 34,549
 
$981.5
 
$999.9
 10,169
 10,555
 
$115.5
 
$106.1
 40,180
 49,172

Temperatures - HDD and CDDHeating degree days (HDD) are calculated using a simple average of the high and low temperatures each day compared to a 65 degree base. Normal degree days are calculated using a rolling 20-year average of historical HDD and CDD.HDD. The following table summarizes the approximate quarterly temperature statistics and resulting impacts on IPL’s and WPL’s electric and gas sales.
 2017 2016 Resulting Impact in 2017 Compared to 2016
First quarter (HDD)13% warmer than normal 10% warmer than normal Decrease in IPL’s and WPL’s electric and gas sales due to lower demand by customers for heating
Second quarter (CDD)2% cooler - 13% warmer than normal 10% - 35% warmer than normal Decrease in IPL’s and WPL’s electric sales due to lower demand by customers for air cooling
Third quarter (CDD)7% - 14% cooler than normal 20% warmer than normal Decrease in IPL’s and WPL’s electric sales due to lower demand by customers for air cooling
 2018 2017 Resulting Impact in 2018 Compared to 2017
First quarter (HDD)2% colder than normal 13% warmer than normal Increase in IPL’s and WPL’s electric and gas sales due to higher demand by customers for heating

Estimated increases (decreases) to electric and gas margins from the impacts of temperatures for the three and nine months ended September 30March 31 were as follows (in millions):
 Electric Margins Gas Margins
 Three Months Nine Months Three Months Nine Months
 2017 2016 Change 2017 2016 Change 2017 2016 Change 2017 2016 Change
IPL
($4) 
$7
 
($11) 
($8) 
$7
 
($15) 
$—
 
$—
 
$—
 
($3) 
($2) 
($1)
WPL(4) 4
 (8) (9) 3
 (12) (1) (1) —
 (3) (2) (1)
Total Alliant Energy
($8) 
$11
 
($19) 
($17) 
$10
 
($27) 
($1) 
($1) 
$—
 
($6) 
($4) 
($2)


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 Electric Margins Gas Margins
 2018 2017 Change 2018 2017 Change
IPL
$—
 
($5) 
$5
 
$—
 
($3) 
$3
WPL1
 (4) 5
 1
 (2) 3
Total Alliant Energy
$1
 
($9) 
$10
 
$1
 
($5) 
$6

Utility Electric Margin Variances - The following items contributed to increased (decreased) utility electric margins for the three and nine months ended September 30, 2017March 31, 2018 compared to the same periodsperiod in 2016 were2017 as follows (in millions):
 Three Months Nine Months
 Alliant Energy IPL WPL Alliant Energy IPL WPL
Higher margins at IPL from the impact of its 2016 Test Year interim retail electric base rate increase (a)
$34
 
$34
 
$—
 
$54
 
$54
 
$—
Higher margins at WPL from the impact of its 2017/2018 Test Period retail electric base rate increase (b)4
 —
 4
 42
 —
 42
Retail electric customer billing credits at IPL in 20163
 3
 —
 7
 7
 —
Estimated changes in sales caused by temperatures (Refer to “Temperatures” above for details)(19) (11) (8) (27) (15) (12)
Changes in electric fuel-related costs, net of recoveries at WPL (c)(2) —
 (2) (11) —
 (11)
Revenue requirement adjustment in 2016 related to certain tax benefits from tax accounting method changes at IPL(4) (4) —
 (11) (11) —
Lower wholesale margins at WPL primarily due to the expiration of a wholesale power supply agreement on May 31, 2017(6) —
 (6) (8) —
 (8)
Other7
 4
 3
 9
 4
 5
 
$17
 
$26
 
($9) 
$55
 
$39
 
$16
 Alliant Energy IPL WPL
Higher margins at IPL from the impact of its 2016 Test Year interim retail electric base rate increase (Refer to Note 2 for details)

$23
 
$23
 
$—
Higher revenues at IPL due to electric tax benefit rider credits on customers’ bills in 201717
 17
 —
Estimated changes in sales volumes caused by temperatures (Refer to “Temperatures” above for details)10
 5
 5
Changes in electric fuel-related costs, net of recoveries at WPL (a)6
 —
 6
Lower transmission cost recovery amortization at WPL (b)6
 —
 6
Decrease in revenues due to deferral of higher taxes collected to be returned to customers (deferral is offset by lower tax expense from the effects of Tax Reform) (Refer to Note 2 for details)
(17) (7) (10)
Lower wholesale margins at WPL primarily due to the expiration of a wholesale power supply agreement on May 31, 2017(7) —
 (7)
Other(4) (3) (1)
 
$34
 
$35
 
($1)

(a)
In April 2017, IPL filed a request with the IUB to increase annual electric base rates for its Iowa retail electric customers by $176 million, or approximately 12%. An interim retail electric base rate increase of $102 million, or approximately 7%, on an annual basis, was implemented effective April 13, 2017. Refer to “Rate Matters” for discussion of IPL’s proposed IPL electric rate review settlement.
(b)
In December 2016,WPL received an order from the PSCW authorizing WPL to implement an increase in annual retail electric rates of $9 million, or approximately 1%. The $9 million net annual retail electric rate increase reflects a $60 million increase in base rates, partially offset by a $51 million reduction in fuel-related costs, using an estimate for 2017 fuel-related costs. The increase was effective January 1, 2017 and extends through the end of 2018. WPL no longer has winter rates that are lower than summer rates. Thus, the quarter-over-quarter variances resulting from the retail electric base rate increase will be smaller during the summer quarters, compared to the winter quarters.
(c)
WPL estimates the decrease to electric margins from amounts within the approved bandwidth of plus or minus 2% of forecasted fuel-related expenses determined by the PSCW each year was approximately $6 million for the ninethree months ended September 30, 2017. WPL estimates the increasesMarch 31, 2017. The impact to electric margins from amounts within the bandwidth were approximately $2 million and $5 millionwas not material for the three and ninemonths ended September 30,March 31, 2018.
(b)The December 2016 respectively.PSCW order for WPL’s 2017/2018 Test Period electric and gas base rate review authorized changes in electric transmission cost recovery amortizations for 2018.

Electric Sales Trends - Alliant Energy’s retail electric sales volumes decreased 3% andincreased 2% for the three and nine months ended September 30, 2017March 31, 2018 compared to the same periodsperiod in 2016, respectively.2017. The decreases wereincrease was primarily due to the impact of lowerhigher residential and commercial sales due to cooler summercolder temperatures during the three and nine months ended September 30, 2017March 31, 2018 compared to the same periodsperiod in 2016, partially offset by increases in WPL’s industrial sales from higher customer production and customer expansions. The nine-month decrease was also impacted by an extra day of retail sales during 2016 due to the leap year.2017.

Utility Gas Margin Variances - The following items contributed to increased (decreased) utility gas margins for the three and nine months ended September 30, 2017March 31, 2018 compared to the same periodsperiod in 2016 were2017 as follows (in millions):
 Three Months Nine Months
 Alliant Energy IPL WPL Alliant Energy IPL WPL
Higher margins at WPL from the impact of its 2017/2018 Test Period retail gas base rate increase (a)
$2
 
$—
 
$2
 
$6
 
$—
 
$6
Higher revenues at IPL due to lower gas tax benefit rider credits on customer’s bills (Refer to Note 2 for details)
1
 1
 —
 4
 4
 —
Estimated changes in sales caused by temperatures (Refer to “Temperatures” above for details)—
 —
 —
 (2) (1) (1)
Other1
 1
 —
 3
 3
 —
 
$4
 
$2
 
$2
 
$11
 
$6
 
$5
 Alliant Energy IPL WPL
Higher revenues at IPL related to changes in recovery amounts for energy efficiency costs through the energy efficiency rider (mostly offset by changes in energy efficiency expense included in other operation and maintenance expenses)
$7
 
$7
 
$—
Estimated changes in sales volumes caused by temperatures (Refer to “Temperatures” above for details)6
 3
 3
Other(1) 2
 (3)
 
$12
 
$12
 
$—

(a)
In December 2016,WPL received an order from the PSCW authorizing WPL to implement an increase in annual retail gas base rates of $9 million, or approximately 13%. The increase is effective January 1, 2017 and extends through the end of 2018.

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Other Operation and Maintenance Expenses - The following items contributed to (increased) decreased other operation and maintenance expenses for the three and nine months ended September 30, 2017March 31, 2018 compared to the same periodsperiod in 2016 were2017 as follows (in millions):
 Three Months Nine Months
 Alliant Energy IPL WPL Alliant Energy IPL WPL
Higher energy efficiency cost recovery amortizations at WPL (a)
($7) 
$—
 
($7) 
($20) 
$—
 
($20)
(Higher) lower bad debt expense(1) 1
 (2) (9) (3) (6)
Charges related to cancelled software projects in 2017(6) (3) (3) (6) (3) (3)
Write-down of regulatory assets due to the proposed IPL electric rate review settlement in 2017(4) (4) —
 (4) (4) —
(Higher) lower equity-based performance compensation expense(1) —
 —
 7
 4
 3
Other(2) (4) —
 3
 (3) 3
 
($21) 
($10) 
($12) 
($29) 
($9) 
($23)
 Alliant Energy IPL WPL
Higher energy efficiency expense at IPL (primarily offset by gas revenues)
($6) 
($6) 
$—
Higher generation operation and maintenance expenses, primarily due to the Marshalltown Generating Station and timing of expenditures(5) (3) (2)
Other(3) (3) —
 
($14) 
($12) 
($2)

(a)The December 2016 PSCW order for WPL’s 2017/2018 Test Period electric and gas base rate review authorized changes in energy efficiency cost recovery amortizations for 2017 and 2018.

Interest ExpenseOther Income and OtherDeductions Variances - The following items contributed to (increased) decreased interest expenseother income and otherdeductions for the three and nine months ended September 30, 2017March 31, 2018 compared to the same periodsperiod in 2016 were2017 as follows (in millions):
Three Months Nine Months
Alliant Energy IPL WPL Alliant Energy IPL WPLAlliant Energy IPL WPL
Higher interest expense primarily due to higher average outstanding long-term debt balances
($5) 
($2) 
$—
 
($14) 
($8) 
$—

($7) 
($2) 
($2)
Lower equity income from unconsolidated investments at WPL from the transfer of its investment in ATC LLC to ATI on December 31, 2016—
 —
 (9) —
 —
 (29)
Higher (lower) AFUDC primarily due to increased (decreased) construction work in progress balances(6) (9) 3
 (8) (11) 4
(2) (7) 5
Higher equity income primarily related to increased earnings from the non-utility wind farm in Oklahoma (Refer to Note 5 for details)
10
 —
 —
Other1
 —
 —
 4
 —
 (1)2
 1
 1

($10) 
($11) 
($6) 
($18) 
($19) 
($26)
$3
 
($8) 
$4

Income Taxes - Refer to Note 89 for details of effective income tax rates from continuing operations.

STRATEGIC OVERVIEW

The strategic overview summary included in the 20162017 Form 10-K has not changed materially, except as described below.

Generation Plans -
Natural Gas-FiredWind Generation -
IPL’s ConstructionExpansion of MarshalltownWind Generation - In April 2018, IPL received approval from the IUB for advance rate-making principles for up to 500 MW of new wind generation, which is in addition to the 500 MW of new generation approved by the IUB in October 2016. The April 2018 IUB decision approved IPL’s requested advance rate-making principles, except for the return on common equity for the calculation of AFUDC during the construction period. IPL requested a return that was the greater of 10.0% or whatever percentage the IUB finds reasonable during IPL’s most recent retail electric rate proceeding, and the IUB approved a return of 9.6%.

WPL’s Expansion of Wind Generation - Refer to Note 3 for discussion of IPL’s constructionWPL’s April 2018 acquisition of Marshalltown, which was completed in April 2017. Final capital expenditures are currently estimated to be approximately $645 million to construct55 MW of the EGU and a pipeline to supply natural gas to the EGU, excluding transmission network upgrades and AFUDC.Forward Wind Energy Center.

Coal-Fired Generation -
WPL’s Construction of West RiversidePlant Retirement - In October 2017, WPL received an order from the PSCW authorizing various electric cooperatives, which currently have wholesale power supply agreements with WPL,Refer to acquire approximately 65 MW of West Riverside while the EGU is being constructed. As part“Critical Accounting Policies and Estimates” for discussion of the electric cooperatives’ acquisitions, which are currently expected to be completedretirement of IPL’s M.L. Kapp Unit 2 by June 1, 2018.

RATE MATTERS

The rate matters summary included in the fourth quarter of 2017 the current wholesale power supply agreements with the various electric cooperatives will be extended by at least four years until 2026 with automatic continuation of such agreements unless terminated by either party, with a five-year notice requirement.Form 10-K has not changed materially, except as described below.


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Wind Generation - The strategic plan includes the planned expansion of wind generation as follows. Estimated capital expenditures for the planned wind generation projects for 2017 through 2020 are included in the “Renewable projects” line in the construction and acquisition expenditures table in “Liquidity and Capital Resources.”
Wind Generation (a)Regulatory Application Filing Status
IPL - up to 500 MWApproved by the IUB in October 2016
IPL - up to 500 MW (b)Filed with the IUB in August 2017
WPL - up to 200 MW (b)Plan to file with the PSCW in the fourth quarter of 2017

(a)IPL and WPL believe their respective planned expansion of wind generation will qualify for the full level of production tax credits as a result of progress payments in 2016 for wind turbines, and plan to place these wind projects into service by the fourth quarter of 2020.
(b)The amount and timing of these wind projects will largely depend on regulatory approvals and the acquisition of wind sites.

IPL’s Expansion of Wind GenerationRetail Base Rate Filings - In October 2016, IPL received approval from the IUB for up to 500 MW of new wind generation. In August 2017, IPL filed an application with the IUB for advance rate-making principles for up to 500 MW of additional wind generation. The advance rate-making principles requested by IPL in the August 2017 application were as follows:

Up to 500 MW of additional wind generation that qualifies for the full level of production tax credits, as long as the project is located in Iowa, with a cost cap of $1,780/kilowatt, including AFUDC and transmission costs. Any costs incurred in excess of this $1,780/kilowatt cost cap are expected to be incorporated into rates if determined to be reasonable and prudent.
A depreciable life of the wind generation facilities of 40 years, unless changed as a result of a contested case before the IUB.
An 11.0% return on common equity, with the exception of certain transmission facilities classified as intangible assets, which would earn the rate of return on common equity the IUB finds reasonable during a future rate review.
A return on common equity for the calculation of AFUDC during the construction period that is the greater of 10.0% or the percentage the IUB finds reasonable during IPL’s retail electric rate review for the 2016 Test Year.
The application of double leverage is deferred until IPL’s next retail electric base rate review or other future proceeding.
Amortization over a 10-year period of IPL’s prudently incurred and unreimbursed costs, effective with IPL’s next retail electric base rate review, if IPL cancels the construction of the wind generation.

Franklin County Wind Farm - Refer to Note 3 for discussion of the transfer of the Franklin County wind farm assets from AEF to IPL in April 2017.

WPL’s Proposed Acquisition of Forward Wind Energy Center - In October 2017, WPL, along with Wisconsin Public Service Corporation and Madison Gas and Electric Company, entered into definitive agreements to acquire the assets of the Forward Wind Energy Center (FWEC), which is a 129 MW wind farm located in Wisconsin. WPL currently expects to acquire 55 MW of FWEC for approximately $74 million. WPL currently expects to file for approval from the PSCW and FERC in the fourth quarter of 2017, with decisions expected by the second quarter of 2018. WPL, Wisconsin Public Service Corporation and Madison Gas and Electric Company have been receiving electricity from FWEC under purchased power agreements since FWEC began commercial operations in 2008. Upon completion of the acquisitions, such purchased power agreements will terminate. This proposed acquisition is included in WPL’s plans for up to 200 MW of additional wind generation discussed above.

Coal-Fired Generation -
IPL’s Environmental Controls Projects - In May 2017, the IUB approved IPL’s most recent emissions plan and budget, which includes the SCR currently under construction at Ottumwa Unit 1.

Plant Retirements and Fuel Switching - In June 2017, IPL retired Sutherland Units 1 and 3 and Dubuque Units 3 and 4, and fuel switched Marshalltown Combustion Turbine Units 1-3 from oil to natural gas. Refer to Note 2 for further discussion of the Sutherland Units 1 and 3 retirement.

Non-regulated Operations - The strategic plan for Alliant Energy’s non-regulated operations involves maintaining a modest portfolio of businesses that are accretive to earnings and cash flows. The non-regulated strategic plan continues to evolve through exploration of renewable investment opportunities within and outside of Alliant Energy’s service territories.

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Non-regulated Wind Investment in Oklahoma - In July 2017, a wholly-owned subsidiary of AEF acquired a 50% cash equity ownership interest in a 225 MW non-regulated wind farm located in Oklahoma. Refer to Note 5(a) for further discussion.

RATE MATTERS

The rate matters summary included in the 2016 Form 10-K has not changed materially, except as described below.

IPL’s Retail ElectricGas Rate Review (2016(2017 Test Year) - In April 2017,May 2018, IPL filed a request with the IUB to increase annual electricgas base rates for its Iowa retail electricgas customers by $20 million, or approximately 8%. The request was based on a 2017 historical Test Year as adjusted for certain known and measurable changes occurring up to 12 months after the commencement of the proceeding. The key drivers for the filing included recovery of capital projects, partially offset by the benefits of Tax Reform. An interim rates wereretail gas rate increase of $11 million, or approximately 5%, on an annual basis, will be implemented effective April 13, 2017. In September 2017,May 14, 2018. The interim rate increase does not require regulatory approval; however, it will be subject to refund pending determination of final rates. IPL reachedcurrently expects a partial, non-unanimous settlement agreementdecision from the IUB in 2019 with final rates effective by the Iowa Officesecond quarter of Consumer Advocate,2019. The IUB must issue a decision on requests for retail rate changes within 10 months of the Iowa Business Energy Coalition anddate of the Large Energy Group.application for which changes are filed. The requested interim and final (based on proposed settlement) rate increases were calculated based on the following (Return on Common Equity (ROE)):following:
 Interim Rates Final Rates (Proposed Settlement)
Regulatory capital structure:   
Common equity49.1% 49.0%
Long-term debt46.3% 46.8%
Preferred equity4.6% 4.2%
After-tax weighted-average cost of capital:   
Marshalltown (ROE - 11.0%)8.1% 8.0%
Emery (ROE - 12.23%)8.7% 8.6%
Whispering Willow - East (ROE - 11.7%)8.4% 8.3%
Other (ROE - 9.6%) (a)7.4% 7.3%
Retail electric rate base (b)$3.8 billion $4.0 billion
 Interim Rates Final Rates
Regulatory capital structure:   
Common equity (CE)49.6% 53.0%
Long-term debt (LD)46.5% 43.2%
Preferred equity3.9% 3.8%
After-tax weighted-average cost of capital (WACC)7.4% 7.5%
Return on common equity (ROE)9.8% 9.8%
Retail gas rate base (a)$460 million $509 million

(a)Other ROE of 9.6% for interim rates reflects the application of double leverage. Prior to application of double leverage, Other ROE for interim rates was 10.0%. Other ROE of 9.6% for final rates (based on proposed settlement) does not reflect the application of double leverage.
(b)The retail electricgas rate base for interim rates includes post-test year capital additions placed in service prior to the rate filing in April 2017, including Marshalltown and the Franklin County wind farm.May 2018. The proposed retail electricgas rate base for final rates (based on proposed settlement) also includes deferred tax assets for production tax credits generated by Whispering Willow - East and post-test year capital additions expected to be placed in service by September 30, 2017.2018.

Refer to Note 2 for discussion of IPL’s initial request, interim rates and proposed settlement, as well as details for a write-down of regulatory assets recorded by IPL in the third quarter of 2017 related to the proposed settlement.

WPL’s Retail Fuel-relatedElectric Rate FilingsReview (2016 Test Year) - Refer to Note 2 for discussion of WPL’sIPL’s final annual retail fuel-relatedelectric rate filingsincrease for the 2016 2017 and 2018 Test Years.Year, which was effective May 1, 2018.

Planned Utility Rate ReviewsTax Reform -
In January 2018, the IUB issued an order requiring IPL and other investor-owned utilities in Iowa to track all calculated differences since January 1, 2018 resulting from Tax Reform. In April 2018, the IUB issued an order on IPL’s Retail Gas Rate Review (2017 Test Year) - IPL currently expectselectric and gas Tax Reform proposals. The IUB order approved the return of approximately $35 million of estimated annual tax benefits for 2018 to make aIPL’s retail electric customers utilizing the tax benefit rider effective May 1, 2018. These benefits are subject to true-up. The IUB order also approved the return of approximately $3 million of estimated annual tax benefits for 2018 to IPL’s retail gas rate filing in the second quarter of 2018 based on a 2017 historical Test Year. The key drivers for the anticipated filing include recovery of capital projects. Any rate changes are expectedcustomers utilizing interim rates to be implemented May 14, 2018 for IPL’s 2017 Test Year gas rate review. These benefits are subject to further review by the IUB. Lastly, the IUB order determined the excess deferred taxes resulting from the remeasurement of accumulated deferred income taxes caused by Tax Reform (approximately $370 million revenue requirement) will be addressed in two phases with interim rates effective approximately 10 days after the filing and final rates effective approximately 10 months after the filing date.

WPL’s Retail Electric and Gas Rate Review (2019/2020 Test Period) - WPL currently expects to make aIPL’s next retail electric and gas rate filingreviews.

In January 2018, the PSCW issued an order directing WPL and other investor-owned utilities in Wisconsin to defer the second quarter of 2018 for the 2019/2020 Test Period. Any rate changes granted from this request are expected to be effective onrevenue requirement impacts since January 1, 2019.2018 resulting from Tax Reform. In April 2018, WPL currently expectsreceived a decision from the PSCW regarding this rate filing bydirecting WPL to return annual tax benefits for 2018 to WPL’s retail electric and gas customers, which WPL currently estimates to be approximately $43 million. The estimated tax benefits related to the first half of 2018 will be provided as a one-time credit on WPL’s retail electric and gas customers’ July 2018 bills. Thereafter, WPL currently expects to provide a monthly refund equal to one-twelfth of the estimated annual tax benefits for 2018 to its retail electric and gas customers through the end of 2018. These billing credits are subject to true-up. The PSCW decision also determined the excess deferred taxes resulting from the remeasurement of accumulated deferred income taxes caused by Tax Reform (approximately $460 million revenue requirement) will be addressed in WPL’s next retail electric and gas rate review.

ENVIRONMENTAL MATTERSIn March 2018, FERC issued an order granting a waiver request filed in February 2018 by a group of MISO transmission owners, including ITC Midwest LLC and ATC, allowing transmission rates to be updated to reflect the impacts resulting from Tax Reform. As a result, beginning in March 2018, amounts billed by ITC Midwest LLC and ATC decreased due to the impacts from Tax Reform. IPL and WPL currently expect lower electric transmission service expense of approximately $35 million and $10 million, respectively, in 2018 due to Tax Reform. IPL began providing the benefits of the lower transmission service expenses to its electric customers utilizing the transmission cost recovery mechanism effective May 1, 2018. WPL will defer the benefits of the lower transmission service expenses from Tax Reform until a future electric rate review. Based on IPL’s and WPL’s electric transmission cost recovery mechanisms, they currently do not expect that any changes to electric transmission service costs billed by ITC Midwest LLC and ATC, respectively, will have a material impact on their financial condition and results of operations.

The environmental matters summary included in the 2016 Form 10-K has not changed materially.

LEGISLATIVE MATTERS

The legislative matters summary included in the 2016 Form 10-K has not changed materially.

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LIQUIDITY AND CAPITAL RESOURCES

The liquidity and capital resources matters summary included in the 20162017 Form 10-K has not changed materially, except as described below.

Liquidity Position - At September 30, 2017,March 31, 2018, Alliant Energy had $9$19 million of cash and cash equivalents, $570$618 million ($13995 million at the parent company, $256$204 million at IPL and $175$319 million at WPL) of available capacity under the revolving credit facility and $2 million ofno available capacity at IPL under its sales of accounts receivable program.

Capital Structure - Capital structures at September 30, 2017March 31, 2018 were as follows (Long-term Debt (including current maturities) (LD); Short-term Debt (SD); Common Equity (CE); IPL’s Preferred Stock (PS)):
lnt9302017_chart-00639.jpglnt9302017_chart-01779.jpglnt9302017_chart-03185.jpgchart-0bc25d3d26745f7d9a5a01.jpgchart-3273d951649154e59f1a01.jpgchart-ebced145bcd256e08d5a01.jpg
Tax Reform - Refer to “Rate Matters” for discussion of expected refunds in 2018 to IPL’s and WPL’s retail electric and gas customers related to tax benefits resulting from Tax Reform.

Cash Flows - Selected information from the cash flows statements was as follows (in millions):
Alliant Energy IPL WPLAlliant Energy IPL WPL
2017 2016 2017 2016 2017 20162018 2017 2018 2017 2018 2017
Cash and cash equivalents, January 1
$8.2
 
$5.8
 
$3.3
 
$4.5
 
$4.2
 
$0.4
Cash, cash equivalents and restricted cash, January 1
$33.9
 
$13.1
 
$7.2
 
$4.2
 
$24.2
 
$6.9
Cash flows from (used for):    ��                 
Operating activities883.4
 654.0
 470.6
 256.5
 361.2
 439.3
89.3
 119.0
 (65.2) (38.4) 141.7
 145.6
Investing activities(1,072.3) (771.8) (493.6) (435.4) (470.2) (326.7)(85.2) (87.2) 55.6
 78.4
 (128.7) (149.3)
Financing activities189.9
 196.7
 24.4
 252.1
 108.0
 (107.4)(9.8) (29.9) 8.9
 (39.2) (31.3) 1.6
Net increase (decrease)1.0
 78.9
 1.4
 73.2
 (1.0) 5.2
(5.7) 1.9
 (0.7) 0.8
 (18.3) (2.1)
Cash and cash equivalents, September 30
$9.2
 
$84.7
 
$4.7
 
$77.7
 
$3.2
 
$5.6
Cash, cash equivalents and restricted cash, March 31
$28.2
 
$15.0
 
$6.5
 
$5.0
 
$5.9
 
$4.8

Operating Activities -
Nine Months Ended September 30, 2017 vs. Nine Months Ended September 30, 2016 - The following items contributed to increased (decreased) operating activity cash flows for the ninethree months ended September 30, 2017March 31, 2018 compared to the same period in 20162017 (in millions):
 Alliant Energy IPL WPL
Changes in the level of cash proceeds from IPL’s sales of accounts receivable
$95
 
$95
 
$—
Higher collections at IPL due to interim retail electric base rate increase effective April 13, 201754
 54
 —
Higher collections at WPL due to new retail electric and gas base rates in 201748
 —
 48
Changes in cash collateral balances38
 —
 —
Changes in levels of production fuel11
 23
 (12)
Timing of WPL’s fuel-related cost recoveries from customers(49) —
 (49)
Changes in income taxes paid/refunded(3) 13
 (40)
Other (primarily due to other changes in working capital)35
 29
 (25)
 
$229
 
$214
 
($78)
 Alliant Energy IPL WPL
Refunds received from ITC Midwest LLC and ATC in 2017
($51) 
($40) 
($11)
Higher collections at IPL due to interim retail electric base rate increase effective April 13, 201723
 23
 —
Other (primarily due to other changes in working capital)(2) (10) 7
 
($30) 
($27) 
($4)

Investing Activities - The following items contributed to increased (decreased) investing activity cash flows for the three months ended March 31, 2018 compared to the same period in 2017 (in millions):
 Alliant Energy IPL WPL
Lower (higher) utility construction expenditures (a)
($66) 
($91) 
$24
Changes in the amount of cash receipts on sold receivables70
 70
 —
Other(2) (2) (3)
 
$2
 
($23) 
$21

(a)Largely due to higher expenditures for IPL’s expansion of wind generation and IPL’s advanced metering infrastructure, partially offset by lower expenditures for IPL’s Marshalltown Generating Station and WPL’s electric and gas distribution systems.


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Investing Activities -
Nine Months Ended September 30, 2017 vs. Nine Months Ended September 30, 2016 - The following items contributed to increased (decreased) investing activity cash flows for the nine months ended September 30, 2017 compared to the same period in 2016 (in millions):
 Alliant Energy IPL WPL
Higher utility construction expenditures (a)
($166) 
($34) 
($147)
Non-regulated wind investment in Oklahoma (Refer to Note 5(a) for details)
(98) —
 —
Proceeds from the liquidation of company-owned life insurance policies in 2016(31) (19) —
Other(6) (5) 3
 
($301) 
($58) 
($144)

(a)Largely due to higher expenditures for WPL’s West Riverside facility, IPL’s and WPL’s electric and gas distribution systems and IPL’s expansion of wind generation, partially offset by lower expenditures for IPL’s Marshalltown facility and WPL’s scrubber and baghouse at Edgewater Unit 5.

Construction and Acquisition Expenditures - Construction and acquisition expenditures for 2017 through 2021 are currently anticipated as follows (in millions). Cost estimates represent Alliant Energy’s, IPL’s and WPL’s portion of total escalated construction expenditures and exclude AFUDC and capitalized interest, if applicable. Such estimates reflect impacts to Alliant Energy’s and WPL’s capital expenditures resulting from purchase options by certain electric cooperatives for a partial ownership interest in West Riverside, as well as additional capital expenditures related to Columbia that WPL is expected to incur related to agreements entered into with Wisconsin Public Service Corporation and Madison Gas and Electric Company. Refer to “Strategic Overview” for further discussion of certain key projects impacting construction and acquisition plans related to the utility business.
 Alliant Energy IPL WPL
 20172018201920202021 20172018201920202021 20172018201920202021
Generation:                 
Renewable projects
$180

$655

$850

$140

$85
 
$210

$565

$725

$50

$85
 
$—

$90

$125

$90

$—
West Riverside235
225
90
10
—
 —
—
—
—
—
 235
225
90
10
—
Marshalltown30
—
—
—
—
 30
—
—
—
—
 —
—
—
—
—
Other220
140
95
150
140
 85
60
50
80
75
 135
80
45
70
65
Distribution:                 
Electric systems480
440
435
485
560
 290
260
250
290
345
 190
180
185
195
215
Gas systems130
130
95
90
115
 90
75
50
55
65
 40
55
45
35
50
Other210
130
110
125
100
 30
25
20
25
20
 10
10
10
10
10
 
$1,485

$1,720

$1,675

$1,000

$1,000
 
$735

$985

$1,095

$500

$590
 
$610

$640

$500

$410

$340

Financing Activities -
Nine Months Ended September 30, 2017 vs. Nine Months Ended September 30, 2016 - The following items contributed to increased (decreased) financing activity cash flows for the ninethree months ended September 30, 2017March 31, 2018 compared to the same period in 20162017 (in millions):
 Alliant Energy IPL WPL
Lower net proceeds from issuance of long-term debt
($300) 
($300) 
$—
Net changes in the amount of commercial paper and other short-term borrowings outstanding203
 44
 180
Higher net proceeds from common stock issuances123
 —
 —
Higher capital contributions from IPL’s and WPL’s parent company, Alliant Energy—
 35
 40
Other (includes higher dividend payments in 2017)(33) (7) (5)
 
($7) 
($228) 
$215

FERC Financing Authorization - Pursuant to a 2015 FERC authorization, IPL’s current remaining authority for short-term debt securities outstanding at any one time (including borrowings from its parent) is $256 million as of September 30, 2017.

State Regulatory Financing Authorization - In August 2017, WPL received authorization from the PSCW to have up to $400 million of short-term borrowings and/or letters of credit outstanding at any time through the earlier of the expiration date of WPL’s credit facility agreement (including extensions) or December 2024.

Common Stock Dividends - Refer to “Executive Overview” for discussion of expected common stock dividends in 2018.

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 Alliant Energy IPL WPL
Changes in outstanding checks that have not yet cleared the bank
$23
 
$15
 
$4
Net changes in the amount of commercial paper outstanding3
 37
 (33)
Other (includes higher dividend payments in 2018)(6) (4) (4)
 
$20
 
$48
 
($33)

Common Stock Issuances - Refer to Note 6 for discussion of common stock issuances by Alliant Energy during the ninethree months ended September 30, 2017. Refer to “Executive Overview” for discussion of expected issuances of common stock inMarch 31, 2018.

Short-term Debt - In July 2017, AEF entered into a $95 million, 364-day variable-rate term loan credit agreement (with Alliant Energy as guarantor) related to the acquisition of a non-regulated wind farm located in Oklahoma. Refer to Note 7(a) for further discussion.

In August 2017, Alliant Energy, IPL and WPL entered into a single new credit facility agreement, which expires in August 2022. The new credit facility agreement includes financial covenants similar to those that were included in the previous credit facility agreements. As of September 30, 2017, the short-term borrowing capacity totaled $1 billion ($300 million for Alliant Energy at the parent company level, $300 million for IPL and $400 million for WPL). There are currently 13 lenders that participate in the credit facility, with aggregate respective commitments ranging from $20 million to $130 million. The credit facility includes a $100 million letter of credit commitment and $50 million swingline commitment, which are available to each of Alliant Energy, IPL and WPL. Subject to certain conditions, Alliant Energy, IPL and WPL may each reallocate and change its initial sublimit up to $500 million, $400 million and $500 million, respectively, within the $1 billion total commitment. Subject to certain conditions, Alliant Energy, IPL and WPL may exercise two extension options, each extending the maturity date by one year. The credit facility has a provision to expand the facility size up to an additional $300 million, for a potential total commitment of $1.3 billion, subject to lender approval for Alliant Energy and subject to lender and regulatory approvals for IPL and WPL.

Long-term Debt - Refer to Note 7(b) for discussion of WPL’s issuance of $300 million of debentures in October 2017 and $40$45.9 million of commercial paper outstanding at September 30, 2017March 31, 2018 classified as long-term debt at Alliant Energy and IPL. Refer to “Executive Overview” for discussion of expected issuances of long-term debtIPL, as well as a $300 million variable-rate term loan credit agreement AEF entered into in 2018.April 2018 (with Alliant Energy as guarantor).

Off-Balance Sheet Arrangements - A summary of Alliant Energy’s off-balance sheet arrangements is included in the 20162017 Form 10-K and has not changed materially from the items reported in the 20162017 Form 10-K, except as described below. Refer to Note 4 for information regarding IPL’s sales of accounts receivable program. Refer to Note 12(d) for information regarding various guarantees and indemnifications related to Alliant Energy’s cash equity ownership interest in a non-regulated wind farm and Alliant Energy’s and IPL’s prior divestiture activities.

Certain Financial Commitments -
Contractual Obligations - A summary of Alliant Energy’s, IPL’s and WPL’s contractual obligations is included in the 20162017 Form 10-K and has not changed materially from the items reported in the 20162017 Form 10-K, except for the items described in Notes 7(b), 12(a)13(a) and 12(b)13(b).

OTHER MATTERS

Market Risk Sensitive Instruments and Positions - The market risks summary included in the 2016 Form 10-K has not changed materially.

Commodity Price - Refer to Note 2 for discussion of WPL’s retail fuel-related rate filings for the 2016, 2017 and 2018 Test Years.

New Accounting Standards - Refer to Note 1(b)1(d) for discussion of new accounting standards impacting Alliant Energy, IPL and WPL.

Critical Accounting Policies and Estimates - The summary of critical accounting policies and estimates included in the 20162017 Form 10-K has not changed materially, except as described below.

Contingencies - In the first quarter of 2017, all warranty periods and performance guarantees expired, and all outstanding warranty claims were resolved, related to Alliant Energy’s past divestiture of RMT. Refer to Note 12(d) for further discussion.

Regulatory Assets and Regulatory Liabilities - Refer to Note 2 for discussion of a write-down of regulatory assets in the third quarter of 2017 related to the recovery of Sutherland Units 1 and 3, and asset retirement obligations deemed no longer probable of recovery in future rates, due to the proposed IPL electric rate review settlement.

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Long-Lived Assets -
Regulated Operations -
Generating Units Subject to Early Retirement- ReferIPL currently expects to Noteretire M.L. Kapp Unit 2 for discussion by June 1, 2018, which had a net book value of IPL’s June 2017 retirement$30 million as of Sutherland Units 1 and 3, and a write-down of regulatory assets in the third quarter of 2017 related to the recovery of these EGUs due to the proposed IPL electric rate review settlement.

March 31, 2018. Alliant Energy and WPLIPL concluded that EdgewaterM.L. Kapp Unit 42 met the criteria to be considered probable of abandonment as of September 30, 2017. WPLMarch 31, 2018. IPL is currently allowed a full recovery of and a full return on this EGU from both its retail and wholesale customers, and as a result, Alliant Energy and WPLIPL concluded that no impairment was required as of September 30, 2017.

Non-regulated Operations -
Franklin County Wind Farm - Refer to Note 3 for discussion of the transfer of the Franklin County wind farm assets from AEF to IPL in April 2017.March 31, 2018.

Other Future Considerations - The summary of other future considerations included in the 2016 Form 10-K has not changed materially, except as described below, and as discussed earlier in MDA and the Notes in Item 1.

2018 Electric Transmission Service Expense - Alliant Energy and IPL currently estimate their total electric transmission service expense in 2018 will be higher than the comparable expense in 2017 by approximately $10 million and $40 million, respectively, as a result of the timing of the MISO transmission owner return on equity complaint refunds received in 2017 and anticipated to be received in 2018, and the related impacts on IPL’s transmission cost rider. WPL currently estimates its total electric transmission service expense in 2018 will be lower than the comparable expense in 2017 by approximately $30 million due to the return of a regulatory liability balance in the escrow account for its electric transmission service expense. WPL’s 2017 and 2018 retail cost estimates were approved in WPL’s retail electric rate review for the 2017/2018 Test Period, and exclude the impacts of an expected lower return on equity and associated refunds resulting from the MISO transmission owner return on equity complaints received in 2017 and anticipated to be received in 2018.

MISO Transmission Owner Return on Equity Complaints - Refer to Note 2 for discussion of refunds that Alliant Energy, IPL and WPL received during the nine months ended September 30, 2017 related to a complaint previously filed by a group of MISO cooperative and municipal utilities requesting a reduction to the base return on equity used by MISO transmission owners, including ITC and ATC LLC.

ITEM 3. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

Quantitative and Qualitative Disclosures About Market Risk are reported in “Other Matters - Market Risk Sensitive Instruments and Positions” in MDA.the 2017 Form 10-K have not changed materially.

ITEM 4. CONTROLS AND PROCEDURES

Alliant Energy’s, IPL’s and WPL’s management evaluated, with the participation of each of Alliant Energy’s, IPL’s and WPL’s Chief Executive Officer, Chief Financial Officer and Disclosure Committee, the effectiveness of the design and operation of Alliant Energy’s, IPL’s and WPL’s disclosure controls and procedures (as defined in Rule 13a-15(e) of the Securities Exchange Act of 1934) as of September 30, 2017March 31, 2018 pursuant to the requirements of the Securities Exchange Act of 1934, as amended. Based on their evaluation, the Chief Executive Officer and the Chief Financial Officer concluded that Alliant Energy’s, IPL’s and WPL’s disclosure controls and procedures were effective as of the quarter ended September 30, 2017.March 31, 2018.

There was no change in Alliant Energy’s, IPL’s and WPL’s internal control over financial reporting that occurred during the quarter ended September 30, 2017March 31, 2018 that has materially affected, or is reasonably likely to materially affect, Alliant Energy’s, IPL’s or WPL’s internal control over financial reporting.


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PART II. OTHER INFORMATION

ITEM 1A. RISK FACTORS

The risk factors described in Item 1A in the 20162017 Form 10-K have not changed materially.


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ITEM 2. UNREGISTERED SALES OF EQUITY SECURITIES AND USE OF PROCEEDS

A summary of Alliant Energy common stock repurchases for the quarter ended September 30, 2017March 31, 2018 was as follows:
  Total Number Average Price Total Number of Shares Maximum Number (or Approximate
  of Shares Paid Per Purchased as Part of Dollar Value) of Shares That May
Period Purchased (a) Share Publicly Announced Plan Yet Be Purchased Under the Plan (a)
July 1 through July 31 2,299
 
$39.81
 — N/A
August 1 through August 31 3,727
 41.93
 — N/A
September 1 through September 30 337
 42.45
 — N/A
  6,363
 41.19
 —  
  Total Number Average Price Total Number of Shares Maximum Number (or Approximate
  of Shares Paid Per Purchased as Part of Dollar Value) of Shares That May
Period Purchased (a) Share Publicly Announced Plan Yet Be Purchased Under the Plan (a)
January 1 through January 31 3,840
 
$39.84
 — N/A
February 1 through February 28 42,509
 38.65
 — N/A
March 1 through March 31 1,175
 38.77
 — N/A
  47,524
 38.74
 —  

(a)AllIncludes 3,840, 4,086 and 1,175 shares wereof Alliant Energy common stock for January 1 through January 31, February 1 through February 28 and March 1 through March 31, respectively, purchased on the open market and held in a rabbi trust under the Alliant Energy Deferred Compensation Plan. There is no limit on the number of shares of Alliant Energy common stock that may be held under the Deferred Compensation Plan, which currently does not have an expiration date. Also includes 38,423 shares of Alliant Energy common stock for February 1 through February 28 transferred from employees to Alliant Energy to satisfy tax withholding requirements in connection with the vesting of certain restricted stock under equity-based compensation plans.

Refer to Note 6 for discussion of IPL’s and WPL’s dividend restrictions and limitations on distributions to their parent company, Alliant Energy.

ITEM 6. EXHIBITS

The following Exhibits are filed herewith or incorporated herein by reference.
Exhibit Number Description
4.1
3.1		 
Five-Year MasterAmended and Restated Bylaws of Alliant Energy Corporation, effective March 13, 2018 (incorporated by reference to Exhibit 3.1 to Alliant Energy’s Form 8-K, filed March 15, 2018 (File No. 1-9894))
10.1
Term Loan Credit Agreement, dated as of August 16, 2017,April 26, 2018, among AEF, Alliant Energy, IPL, WPL, Wells FargoU.S. Bank National Association and the lender parties set forth therein (incorporated by reference to Exhibit 4.110.1 to Alliant Energy’s Form 8-K, filed August 21, 2017April 30, 2018 (File No. 1-9894))
4.2
Officers’ Certificate, dated as of October 10, 2017, creating WPL’s 3.05% Debentures due October 15, 2027 (incorporated by reference to Exhibit 4.1 to WPL’s Form 8-K, filed October 10, 2017 (File No. 0-337))
12.1
 
Ratio of Earnings to Fixed Charges for Alliant Energy
12.2
 
Ratio of Earnings to Fixed Charges and Ratio of Earnings to Combined Fixed Charges and Preferred Dividend Requirements for IPL
12.3
 
Ratio of Earnings to Fixed Charges for WPL
31.1
 
Certification of the Chairman President and Chief Executive Officer for Alliant Energy
31.2
 
Certification of the Senior Vice President, Chief Financial Officer and Treasurer for Alliant Energy
31.3
 
Certification of the Chairman and Chief Executive Officer for IPL
31.4
 
Certification of the Senior Vice President, Chief Financial Officer and Treasurer for IPL
31.5
 
Certification of the Chairman and Chief Executive Officer for WPL
31.6
 
Certification of the Senior Vice President, Chief Financial Officer and Treasurer for WPL
32.1
 
Written Statement of the Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C.§1350 for Alliant Energy
32.2
 
Written Statement of the Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C.§1350 for IPL
32.3
 
Written Statement of the Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C.§1350 for WPL
101.INS XBRL Instance Document
101.SCH XBRL Taxonomy Extension Schema Document
101.CAL XBRL Taxonomy Extension Calculation Linkbase Document
101.LAB XBRL Taxonomy Extension Label Linkbase Document
101.PRE XBRL Taxonomy Extension Presentation Linkbase Document
101.DEF XBRL Taxonomy Extension Definition Linkbase Document


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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, Alliant Energy Corporation, Interstate Power and Light Company and Wisconsin Power and Light Company have each duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized on the 3rd day of November 2017.May 2018.
ALLIANT ENERGY CORPORATION 
Registrant 
  
By: /s/ Benjamin M. BilitzChief Accounting Officer and Controller
Benjamin M. Bilitz(Principal Accounting Officer and Authorized Signatory)
INTERSTATE POWER AND LIGHT COMPANY 
Registrant 
  
By: /s/ Benjamin M. BilitzChief Accounting Officer and Controller
Benjamin M. Bilitz(Principal Accounting Officer and Authorized Signatory)
WISCONSIN POWER AND LIGHT COMPANY 
Registrant 
  
By: /s/ Benjamin M. BilitzChief Accounting Officer and Controller
Benjamin M. Bilitz(Principal Accounting Officer and Authorized Signatory)


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