Exhibit 12.1

ALLIANT ENERGY CORPORATION

RATIO OF EARNINGS TO FIXED CHARGES

|                                                                    | Six Months            |                     
|------------------------------------------------------------------- | --------------------- | --------------------
|                                                                    | Ended June 30,        | Years Ended Dec. 31,
|                                                                    |                       |                     
|                                                                    | 2009                  | 2008                
|                                                                    |                       |                     
|                                                                    | (dollars in millions)
|EARNINGS:                                                           |                       |                     
|Net income from continuing operations attributable to               |                      
|Alliant Energy Corporation common shareowners                       |                       | $101                
|Income tax expense (benefit) (b)                                    |                       | (4                  
|                                                                    |                       |                     
|Subtotal                                                            |                       | 97                  
|Fixed charges as defined                                            |                       | 94                  
|Adjustment for undistributed equity earnings                        |                       | (3                  
|Less:                                                               |                      
|Interest capitalized                                                |                       | -                   
|Preferred dividend requirements of subsidiaries (pre-tax basis) (c) |                       | 9                   
|                                                                    |                       |                     
|Total earnings as defined                                           |                       | $179                
|                                                                    |                       |                     
|FIXED CHARGES:                                                      |                      
|Interest expense                                                    |                       | $71                 
|Interest capitalized                                                |                       | -                   
|Estimated interest component of rent expense                        |                       | 14                  
|Preferred dividend requirements of subsidiaries (pre-tax basis) (c) |                       | 9                   
|                                                                    |                       |                     
|Total fixed charges as defined                                      |                       | $94                 
|                                                                    |                       |                     
|Ratio of Earnings to Fixed Charges (d)                              |                       | 1                   
|                                                                    |                       |                     

(a) For the year ended Dec. 31,
2005, earnings as defined were inadequate to cover fixed charges as defined by $47.1
million.

(b) Includes net interest related to
unrecognized tax benefits.

(c) Preferred dividend requirements
of subsidiaries (pre-tax basis) are computed by dividing the preferred dividend
requirements of subsidiaries by one hundred percent minus the respective year-to-date
effective income tax rate.

(d) The ratio calculation in the
above table relates to Alliant Energy Corporation's continuing operations.