Wisconsin Power and Light Company Issues $4 Million in Customer Credits

Credits will be issued beginning with bills processed on December 10th

MADISON, Wis., Dec. 7 /PRNewswire-FirstCall/ — Wisconsin Power and Light Company (WPL), a subsidiary of Alliant Energy Corporation (NYSE:LNT) , will issue a credit to its electric customers through all billing cycles beginning with bills processed on December 10, 2007. The total credits issued will be approximately $4 million.

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The additional refund represents overall savings from June 2007 through October 2007, and is the specific result of lower fuel costs. Virtually all retail electric users should expect to receive the credit that will vary based on their usage billed during December. For a typical residential customer using 600 kilowatt-hours of electricity per month, the credit would be approximately $2.61.

“WPL meets its customer demands through a balanced and diversified energy portfolio that includes a variety of fuel types, including renewable resources, coal, nuclear and natural gas,” said Barbara Swan, President-WPL. “We welcome the reduction in fuel costs and are pleased we can pass these savings on to our customers during the holiday season.”

The WPL refund complies with today’s order by the Public Service Commission of Wisconsin which allowed WPL to refund any over-collection of fuel costs for the period running from June 2007 through December 2007. The agreement was endorsed by several customer groups, including the Citizens Utility Board and the Wisconsin Industrial Energy Group.

Alliant Energy is an energy-services provider with subsidiaries serving approximately 1 million electric and over 420,000 natural gas customers. Providing its customers in the Midwest with regulated electric and natural gas service is the company’s primary focus. Wisconsin Power and Light, the company’s Wisconsin utility subsidiary, serves 459,000 electric and 182,000 natural gas customers. Alliant Energy, headquartered in Madison, Wis., is a Fortune 1000 company traded on the New York Stock Exchange under the symbol LNT. For more information, visit the company’s Web site at http://www.alliantenergy.com/.

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Source: Alliant Energy Corporation

CONTACT: Media, Rob Crain, +1-608-458-4469, or Investor Relations, Becky
Johnson, +1-608-458-3267, both of Alliant Energy Corporation

Web site: http://www.alliantenergy.com/