ALLIANT ENERGY CORP — Earnings Release 2012

May 4, 2012

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported) May 4, 2012

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
0-4117-1	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

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

[ ] Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

[ ] Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

[ ] Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

[ ] Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 2.02 Results of Operations and Financial Condition.

On May 4, 2012, Alliant Energy Corporation (“Alliant Energy”) issued a press release announcing its earnings for the first quarter ended March 31, 2012. A copy of such press release is furnished as Exhibit 99.1 and is incorporated by reference herein.

Alliant Energy included in the press release income from continuing operations and earnings per share from continuing operations for the first quarter ended March 31, 2012 excluding non-recurring state income tax impacts. Alliant Energy included in the press release income from continuing operations and earnings per share from continuing operations for the first quarter ended March 31, 2011 excluding an impairment charge. Alliant Energy believes these non-GAAP financial measures (financial measures not prepared in accordance with accounting principles generally accepted in the United States of America) are useful to investors because they provide an alternate measure to better understand and compare across periods the operating performance of Alliant Energy without the distortion of items that management believes are not normally associated with ongoing operations, and also 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 management also uses income from continuing operations, as adjusted, to determine incentive compensation.

In addition, Alliant Energy included in the press release Interstate Power and Light Company, Wisconsin Power and Light Company, utility, and non-regulated and parent earnings per share from continuing operations for the first quarter ended March 31, 2012 and 2011. 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 management also uses utility earnings per share from continuing operations to determine incentive compensation.

Item 9.01 Financial Statements and Exhibits.

(a) Not applicable.

(b) Not applicable.

(c) Not applicable.

(d) Exhibits . The following exhibits are being furnished herewith:

(99.1) Alliant Energy Corporation press release dated May 4, 2012.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrants have duly caused this report to be signed on their behalf by the undersigned hereunto duly authorized.

Date: May 4, 2012	ALLIANT ENERGY CORPORATION — By:	/s/ Robert J. Durian
		Robert J. Durian
		Controller and Chief Accounting Officer
	INTERSTATE POWER AND LIGHT COMPANY
Date: May 4, 2012	By:	/s/ Robert J. Durian
		Robert J. Durian
		Controller and Chief Accounting Officer
	WISCONSIN POWER AND LIGHT COMPANY
Date: May 4, 2012	By:	/s/ Robert J. Durian
		Robert J. Durian
		Controller and Chief Accounting Officer

ALLIANT ENERGY CORPORATION

INTERSTATE POWER AND LIGHT COMPANY

WISCONSIN POWER AND LIGHT COMPANY

Exhibit Index to Current Report on Form 8-K

Dated May 4, 2012

Exhibit Number
(99.1)	Alliant Energy Corporation press release dated May 4, 2012.

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