Exhibit 23


     CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in Registration
Statement No. 333-117654 of Alliant Energy Corporation on Form
S-8 of our report dated June 28, 2006, appearing in this Annual
Report on Form 11-K of the Alliant Energy Corporation 401(k)
Savings Plan for the year ended December 31, 2005.





/s/ Deloitte & Touche LLP
- -------------------------

Milwaukee, Wisconsin
June 28, 2006


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