Exhibit 23 INDEPENDENT AUDITORS' CONSENT We consent to the incorporation by reference in Registration Statement Nos. 333-46735 and 333-88306 of Alliant Energy Corporation on Forms S-8 of our report dated June 10, 2003, appearing in this Annual Report on Form 11-K of the Alliant Energy Corporation 401(k) Savings Plan for the year ended December 31, 2002. /s/ Deloitte & Touche LLP Milwaukee, Wisconsin June 30, 2003 18