Cover and table of contents

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-K

☒ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2019

or

☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from to

Name of Registrant, State of Incorporation, Address of Principal Executive Offices, Telephone Number, Commission File Number, IRS Employer Identification Number

ALLIANT ENERGY CORP****ORATION

(a Wisconsin Corporation)

4902 N. Biltmore Lane

Madison, Wisconsin 53718

Telephone (608) 458-3311

Commission File Number - 1-9894

IRS Employer Identification Number - 39-1380265

INTERSTATE POWER & LIGHT CO****MPANY

(an Iowa corporation)

Alliant Energy Tower

Cedar Rapids, Iowa 52401

Telephone (319) 786-4411

Commission File Number - 1-4117

IRS Employer Identification Number - 42-0331370

WISCONSIN POWER & LIGHT CO****MPANY

(a Wisconsin corporation)

4902 N. Biltmore Lane

Madison, Wisconsin 53718

Telephone (608) 458-3311

Commission File Number - 0-337

IRS Employer Identification Number - 39-0714890

This combined Form 10-K is separately filed by Alliant Energy Corporation, Interstate Power and Light Company and Wisconsin Power and Light Company. Information contained in the Form 10-K 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.

Securities registered pursuant to Section 12(b) of the Act:

Alliant Energy Corporation, Common Stock, $0.01 Par Value, Trading Symbol LNT, Nasdaq Global Select Market

Interstate Power and Light Company, 5.100% Series D Cumulative Perpetual Preferred Stock, $0.01 Par Value, Trading Symbol IPLDP, Nasdaq Global Select Market

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrants are well-known seasoned issuers, as defined in Rule 405 of the Securities Act.

Alliant Energy Corporation - Yes ☒ No ☐

Interstate Power and Light Company - Yes ☒ No ☐

Wisconsin Power and Light Company - Yes ☒ No ☐

Indicate by check mark if the registrants are not required to file reports pursuant to Section 13 or Section 15(d) of the Act.

Alliant Energy Corporation - Yes ☐ No ☒

Interstate Power and Light Company - Yes ☐ No ☒

Wisconsin Power and Light Company - Yes ☐ No ☒

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.

Alliant Energy Corporation - Yes ☒ No ☐

Interstate Power and Light Company - Yes ☒ No ☐

Wisconsin Power and Light Company - Yes ☒ No ☐

Indicate by check mark whether the registrants have submitted electronically every Interactive Data File required to be submitted 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 such files).

Alliant Energy Corporation - Yes ☒ No ☐

Interstate Power and Light Company - Yes ☒ No ☐

Wisconsin Power and Light Company - 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.

Alliant Energy Corporation - Large Accelerated Filer ☒ Accelerated Filer ☐ Non-accelerated Filer ☐ Smaller Reporting Company ☐ Emerging Growth Company ☐

Interstate Power and Light Company - Large Accelerated Filer ☐ Accelerated Filer ☐ Non-accelerated Filer ☒ Smaller Reporting Company ☐ Emerging Growth Company ☐

Wisconsin Power and Light Company - Large Accelerated Filer ☐ Accelerated Filer ☐ Non-accelerated Filer ☒ Smaller Reporting Company ☐ Emerging Growth 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.

Alliant Energy Corporation ☐

Interstate Power and Light Company ☐

Wisconsin Power and Light Company ☐

Indicate by check mark whether the registrants are shell companies (as defined in Rule 12b-2 of the Exchange Act).

Alliant Energy Corporation - Yes ☐ No ☒

Interstate Power and Light Company - Yes ☐ No ☒

Wisconsin Power and Light Company - Yes ☐ No ☒

The aggregate market value of the voting and non-voting common equity held by nonaffiliates as of June 30, 2019:

Alliant Energy Corporation - $11.6 billion

Interstate Power and Light Company - $0

Wisconsin Power and Light Company - $0

Number of shares outstanding of each class of common stock as of January 31, 2020:

Alliant Energy Corporation, Common Stock, $0.01 par value, 245,031,019 shares outstanding

Interstate Power and Light Company, Common Stock, $2.50 par value, 13,370,788 shares outstanding (all outstanding shares are owned beneficially and of record by Alliant Energy Corporation)

Wisconsin Power and Light Company, Common Stock, $5 par value, 13,236,601 shares outstanding (all outstanding shares are owned beneficially and of record by Alliant Energy Corporation)

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the Proxy Statement relating to Alliant Energy Corporation’s 2020 Annual Meeting of Shareowners are, or will be upon filing with the Securities and Exchange Commission, incorporated by reference into Part III hereof.

TABLE OF CONTENTS

						Page Number
Definitions						1
Forward-looking Statements						1
Website Access to Reports						3
Part I.	Item 1. Business					3
	Item 1A. Risk Factors					13
	Item 1B. Unresolved Staff Comments					18
	Item 2. Properties					18
	Item 3. Legal Proceedings					20
	Item 4. Mine Safety Disclosures					20
	Information About Executive Officers					20
Part II.	Item 5. Market for Registrants’ Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities					21
	Item 6. Selected Financial Data					22
	Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations					23
	Item 7A. Quantitative and Qualitative Disclosures About Market Risk					39
	Item 8. Financial Statements and Supplementary Data					39
		Alliant Energy Corporation				40
		Interstate Power and Light Company				46
		Wisconsin Power and Light Company				51
		Combined Notes to Consolidated Financial Statements				56
			1. Summary of Significant Accounting Policies			56
			2. Regulatory Matters			62
			3. Property, Plant and Equipment			65
			4. Jointly-owned Electric Utility Plant			66
			5. Receivables			66
			6. Investments			67
			7. Common Equity			68
			8. Preferred Stock			69
			9. Debt			69
			10. Leases			71
			11. Revenues			72
			12. Income Taxes			73
			13. Benefit Plans			75
			14. Asset Retirement Obligations			85
			15. Derivative Instruments			86
			16. Fair Value Measurements			87
			17. Commitments and Contingencies			89
			18. Segments of Business			92
			19. Related Parties			94
			20. Selected Consolidated Quarterly Financial Data (Unaudited)			95
	Item 9. Changes in and Disagreements With Accountants on Accounting and Financial Disclosure					95
	Item 9A. Controls and Procedures					96
	Item 9B. Other Information					98
Part III.	Item 10. Directors, Executive Officers and Corporate Governance					98
	Item 11. Executive Compensation					98
	Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters					98
	Item 13. Certain Relationships and Related Transactions, and Director Independence					99
	Item 14. Principal Accounting Fees and Services					99
Part IV.	Item 15. Exhibits, Financial Statement Schedules					100
	Item 16. Form 10-K Summary					105
Signatures						106

DEFINITIONS

The following abbreviations or acronyms used in this report are defined below:

Abbreviation or Acronym	Definition	Abbreviation or Acronym	Definition
2020 Alliant Energy Proxy Statement	Alliant Energy’s Proxy Statement for the 2020 Annual Meeting of Shareowners	FWEC	Forward Wind Energy Center
AEF	Alliant Energy Finance, LLC	GAAP	U.S. generally accepted accounting principles
AFUDC	Allowance for funds used during construction	GHG	Greenhouse gases
Alliant Energy	Alliant Energy Corporation	IPL	Interstate Power and Light Company
ARO	Asset retirement obligation	IRS	Internal Revenue Service
ATC	American Transmission Company LLC	ITC	ITC Midwest LLC
ATC Holdings	Interest in American Transmission Company LLC and ATC Holdco LLC	IUB	Iowa Utilities Board
ATI	AE Transco Investments, LLC	KWh	Kilowatt-hour
CA	Certificate of authority	Marshalltown	Marshalltown Generating Station
CAA	Clean Air Act	MDA	Management’s Discussion and Analysis of Financial Condition and Results of Operations
CCR	Coal combustion residuals	MGP	Manufactured gas plant
CO2	Carbon dioxide	MISO	Midcontinent Independent System Operator, Inc.
Corporate Services	Alliant Energy Corporate Services, Inc.	MW	Megawatt
CPCN	Certificate of Public Convenience and Necessity	MWh	Megawatt-hour
CWIP	Construction work in progress	N/A	Not applicable
DAEC	Duane Arnold Energy Center	Note(s)	Combined Notes to Consolidated Financial Statements
DCP	Alliant Energy Deferred Compensation Plan	OIP	Alliant Energy 2010 Omnibus Incentive Plan
DLIP	Alliant Energy Director Long Term Incentive Plan	OPEB	Other postretirement benefits
Dth	Dekatherm	PPA	Purchased power agreement
EEP	Energy efficiency plan	PSCW	Public Service Commission of Wisconsin
EGU	Electric generating unit	Receivables Agreement	Receivables Purchase and Sale Agreement
EPA	U.S. Environmental Protection Agency	RES	Renewable energy standards
EPS	Earnings per weighted average common share	Riverside	Riverside Energy Center
FASB	Financial Accounting Standards Board	SEC	Securities and Exchange Commission
Federal Tax Reform	Tax Cuts and Jobs Act	U.S.	United States of America
FERC	Federal Energy Regulatory Commission	VEBA	Voluntary Employees’ Beneficiary Association
Financial Statements	Consolidated Financial Statements	VIE	Variable interest entity
FTR	Financial transmission right	Whiting Petroleum	Whiting Petroleum Corporation
Fuel-related	Electric production fuel and purchased power	WPL	Wisconsin 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:

	1

•

IPL’s and WPL’s ability to obtain adequate and timely rate relief to allow for, among other things, the recovery of and/or the return on costs, including fuel costs, operating costs, transmission costs, deferred expenditures, deferred tax assets, tax expense, capital expenditures, and remaining costs related to EGUs that may be permanently closed and certain other retired assets, earning their authorized rates of return, and the payments to their parent of expected levels of dividends;

•	federal and state regulatory or governmental actions, including the impact of legislation, and 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;

•	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 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 persons and to mitigate their information security concerns;

•	any material post-closing payments related to any past asset divestitures, including the sale of Whiting Petroleum, which could result from, among other things, indemnification agreements, warranties, parental guarantees or litigation;

•	employee workforce factors, including changes in key executives, ability to 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;

•	issues associated with environmental remediation and environmental compliance, including compliance with all environmental and emissions permits, the CCR rule, future changes in environmental laws and regulations, including federal, state or local regulations for CO2 emissions reductions from new and existing fossil-fueled EGUs, and litigation associated with environmental requirements;

•	increased pressure from customers, investors and other stakeholders to more rapidly reduce CO2 emissions;

•	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;

•	continued 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 and the resulting impacts on sales volumes, margins and the ability to collect unpaid bills;

•	the ability to complete construction of wind and solar projects within the cost caps set by regulators and to meet all requirements to qualify for the full level of production tax credits and investment tax credits, respectively;

•	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;

•	disruptions in the supply and delivery of natural gas, purchased electricity and coal;

•	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, including regulations promulgated by the Pipeline and Hazardous Materials Safety Administration;

•	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 excessive heat, storms or natural disasters may have on Alliant Energy’s, IPL’s and WPL’s operations and recovery of costs associated with restoration activities, or on the operations of Alliant Energy’s investments;

•	Alliant 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 market 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;

	2

•	impacts on equity 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 state depreciation, and recoverability of the associated regulatory assets from customers, when the differences reverse in future periods;

•	the impacts of adjustments made to deferred tax assets and 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;

•	the effect of accounting standards issued periodically by standard-setting bodies;

•	the ability to successfully complete tax audits and changes in tax accounting methods with no material impact on earnings and cash flows; and

•	other factors listed in MDA and Item 1A Risk Factors.

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.

WEBSITE ACCESS TO REPORTS

Alliant Energy, IPL and WPL make their periodic and current reports, and amendments to those reports, available, free of charge, on Alliant Energy’s website at www.alliantenergy.com/investors on the same day as such material is electronically filed with, or furnished to, the SEC. Alliant Energy, IPL and WPL are not including the information contained on Alliant Energy’s website as a part of, or incorporating it by reference into, this report.

PART I

This report 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. Unless otherwise noted, the information herein excludes discontinued operations for all periods presented.