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

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Date of Report  
(Date of earliest
event reported): June 13, 2008

Commission Name of Registrant, State of Incorporation, Address of IRS Employer
File Number 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

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 8-K is separately filed by Alliant Energy Corporation and Wisconsin Power and Light Company.

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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 8.01. Other Events.

        Wisconsin Power and Light Company (“WPL”), a wholly owned subsidiary of Alliant Energy Corporation, is updating WPL’s cost estimate for capital expenditures for its proposed addition of a new third unit of the Nelson Dewey Generating Station in Cassville, Wisconsin to an estimated range of $1.1 billion to $1.2 billion, which is an increase from the previously disclosed range of $850 million to $950 million.

        WPL is separately updating its cost estimate for capital expenditures for sulfur dioxide air pollution controls at the two existing units at the Nelson Dewey Generating Station to approximately $200 million, which is an increase from the previously disclosed estimate of $116 million.

        Cost estimates represent WPL’s total escalated construction expenditures and exclude allowance for funds used during construction, if applicable.

        This Current Report on Form 8-K includes forward-looking statements. These forward-looking statements can be identified as such because the statements include words such as “estimate,” “estimated,” “approximately,” or other words of similar import. Similarly, statements that describe future plans or strategies are also forward-looking statements. Such statements are subject to certain risks and uncertainties that could cause actual results to differ materially from those currently anticipated. Actual results could be affected by such factors as: state regulatory actions or local government actions which delay, prevent or alter the proposed plans, including inability to obtain all necessary approvals and permits; unanticipated construction issues, delays or expenditures including increased costs of labor, materials and equipment; failure of equipment and technology to perform as expected; current or future litigation, regulatory investigations, proceedings or inquiries that could impede the implementation of WPL’s plans; political conditions in WPL’s service territories; changes to WPL’s access to capital markets; and economic conditions in WPL’s service territory. These factors should be considered when evaluating the forward-looking statements and undue reliance should not be placed on such statements. The forward-looking statements included herein are made as of the date hereof and Alliant Energy and WPL undertake no obligation to update publicly such statements to reflect subsequent events or circumstances.





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SIGNATURES

        Pursuant to the requirements of the Securities Exchange Act of 1934, Alliant Energy Corporation and Wisconsin Power and Light Company have each duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

ALLIANT ENERGY CORPORATION

Date:  June 13, 2008
By:/s/ Barbara J. Swan
      Barbara J. Swan
      Executive Vice President and General Counsel


Date:  June 13, 2008
WISCONSIN POWER AND LIGHT COMPANY

 
By:/s/ Barbara J. Swan
      Barbara J. Swan
      President









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