UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

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

~~the~~Date ~~Securities~~of ~~Exchange~~Report ~~Act~~(Date of ~~1934~~ earliest event reported) May 3, 2013

Date of Report (Date of earliest event reported): March 14, 2013



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

Commission File Number		Name of Registrant, State of Incorporation, Address of Principal Executive Offices and Telephone Number		IRS EmployerIdentification Number
001-04117		Interstate Power and Light Company (an Iowa corporation) Alliant Energy Tower Cedar Rapids, Iowa 52401 Telephone (319) 786-4411		42-0331370

(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 5 2.0302 Results ~~Amendments to Articles~~ of ~~Incorporation~~Operations orand ~~Bylaws;~~Financial ~~Change in Fiscal Year~~ Condition.

~~Under~~On ~~the~~May ~~restated articles of incorporation~~3, ~~as amended~~2013, ofAlliant ~~Interstate~~Energy ~~Power~~Corporation ~~and Light Company~~ (~~the~~ “~~Company~~Alliant Energy”), ~~the~~issued ~~board~~a ~~of directors~~press isrelease ~~authorized~~announcing ~~without~~its ~~further~~earnings ~~shareholder action to provide~~ for the ~~issuance~~first ofquarter upended ~~to 16,000,000 shares of preferred stock in one or more series. On~~ March 1431, 2013~~, the Company adopted Articles of Amendment of Interstate Power and Light Company (Regarding Designation and Authorization of 5~~.~~100%~~ A ~~Series~~copy ~~D Cumulative Perpetual Preferred Stock) (the “Articles~~ of ~~Amendment”)~~such topress ~~its~~release ~~restated~~is ~~articles~~furnished ~~of incorporation designating 8,000,000 shares of the Company’s preferred stock~~ as ~~“5.100%~~Exhibit ~~Series D Cumulative Perpetual Preferred Stock” (the “Series D Preferred Stock”)~~99.1 ~~The~~and ~~Articles~~is ofincorporated ~~Amendment~~by ~~are~~reference ~~effective as of March 20, 2013~~herein.

~~The~~Alliant ~~terms~~Energy ofincluded in the ~~Series~~press Drelease ~~Preferred~~income ~~Stock~~from ~~are~~continuing ~~set~~operations ~~forth~~and earnings per share from continuing operations for the first quarter ended March 31, 2013 excluding losses on preferred stock redemptions at Interstate Power and Light Company and Wisconsin Power and Light Company. Alliant Energy included in the ~~Articles~~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 believes these non-GAAP financial measures (financial measures not prepared in accordance with accounting principles generally accepted in the United States of ~~Amendment~~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 ~~attached~~not ~~hereto~~normally asassociated ~~Exhibit~~with ~~3.1~~ongoing operations, and ~~incorporated~~ ~~herein~~also byprovide ~~reference~~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 performance-based compensation.

~~Item~~In addition, Alliant Energy included in the press release Interstate Power and Light Company, Wisconsin Power and Light Company, Alliant Energy Corporate Services, Inc., utility and Alliant Energy Corporate Services, Inc., and non-regulated and parent earnings per share from continuing operations for the first quarters ended March 831, 2013 and 2012.01 Alliant ~~Other~~Energy ~~Events~~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 and Alliant Energy Corporate Services, Inc. earnings per share from continuing operations to determine performance-based compensation.

OnItem ~~March 14, 2013, the Company entered into an underwriting agreement (the “Underwriting Agreement”), with Robert W~~9.01 Financial ~~Baird &~~Statements ~~Co. Incorporated, Barclays Capital Inc., J.P. Morgan Securities LLC,~~ and ~~Wells Fargo Securities, LLC, as representatives of the other underwriters named therein, for the sale of 8,000,000 shares (the “Shares”) of the Series D Preferred Stock~~Exhibits. The Series D Preferred Stock was offered to the public at a price of $25.00 per share. The underwriting discount was $0.7875 per share for retail orders and $0.5000 per share for institutional orders. The Company estimates that the net proceeds from this offering will be approximately $194.5 million (after deducting underwriting discounts and estimated offering expenses). The Underwriting Agreement is filed as Exhibit 1.1 hereto and is incorporated herein by reference.

~~Certain~~(a) ofNot ~~the underwriters have performed investment banking and advisory services for the Company from time to time for which they have received customary fees and expenses~~applicable. ~~The underwriters may, from time to time, engage in transactions with and perform services for the Company in the ordinary course of their business.~~

On(b) ~~March 14,~~Not ~~2013, the Company issued a press release announcing that it had priced the offering of the Shares~~applicable. ~~The press release is filed as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.~~

~~Item 9.01.~~(c) ~~Financial~~Not ~~Statements and Exhibits~~applicable.

~~Exhibits are filed herewith in connection with the Registration Statement on Form S-3~~ (~~File No. 333-178577-02~~d) ~~filed~~Exhibits. byThe ~~the~~following ~~Company~~exhibits ~~with~~are ~~the~~being ~~Securities~~furnished ~~and Exchange Commission on December 16, 2011.~~ herewith:

(d99.1) Alliant ~~Exhibits~~Energy Corporation press release dated May 3, 2013.

ExhibitNo.		Description
1.1		Underwriting Agreement dated March 14, 2013, by and among the Company and Robert W. Baird & Co. Incorporated, Barclays Capital Inc., J.P. Morgan Securities LLC, and Wells Fargo Securities, LLC, as representatives of the other underwriters named therein
3.1		Articles of Amendment of Interstate Power and Light Company (Regarding Designation and Authorization of 5.100% Series D Cumulative Perpetual Preferred Stock)
4.1		Form of Preferred Stock Certificate
5.1		Opinion of Godfrey & Kahn, S.C. as to the legality of the Series D Preferred Stock
99.1		Press Release

SIGNATURES

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

~~Dated:~~ALLIANT ~~March 20,~~ENERGY ~~2013~~ CORPORATION

INTERSTATE POWER AND LIGHT COMPANY By: /s/ John E. Kratchmer John E. Kratchmer Vice President and Treasurer



Date: May 3, 2013	By:/s/ Robert J. Durian
	Robert J. Durian
	Controller and Chief Accounting Officer

~~EXHIBIT~~INTERSTATE ~~INDEX~~POWER AND LIGHT COMPANY

ExhibitNo.		Description
Date: May 3, 2013	By:/s/ Robert J. Durian
1.1		Underwriting Agreement dated March 14, 2013, by and among the Company and Robert W. Baird & Co. Incorporated, Barclays Capital Inc., J.P. Morgan Securities LLC, and Wells Fargo Securities, LLC, as representatives of the other underwriters named therein
	Robert J. Durian
3.1		Articles of Amendment of Interstate Power and Light Company (Regarding Designation and Authorization of 5.100% Series D Cumulative Perpetual Preferred Stock)
	Controller and Chief Accounting Officer
4.1		Form of Preferred Stock Certificate
5.1		Opinion of Godfrey & Kahn, S.C. as to the legality of the Series D Preferred Stock
99.1		Press Release

4WISCONSIN POWER AND LIGHT COMPANY



Date: May 3, 2013	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 3, 2013

Exhibit Number


(99.1)	Alliant Energy Corporation press release dated May 3, 2013.

Filing Compare · INTERSTATE POWER & LIGHT CO