Exhibit 12.1

ALLIANT ENERGY CORPORATION

RATIO OF EARNINGS TO FIXED CHARGES

|                                                                   | Years Ended December 31,
|------------------------------------------------------------------ | ------------------------
|                                                                   |                         
|                                                                   | 2005*                   
|                                                                   |                         
|                                                                   | (dollars in millions)   
|EARNINGS:                                                          |                         
|Income from continuing operations                                  | $56.4                   
|Income tax expense (benefit)                                       | (52.9)                  
|                                                                   |                         
|Income from continuing operations before income taxes              | 3.5                     
|                                                                  
|Fixed charges as defined                                           | 226.7                   
|                                                                  
|Adjustment for undistributed equity earnings                       | (41.7)                  
|                                                                  
|Less:                                                             
|Interest capitalized                                               | 3.4                     
|Preferred dividend requirements of subsidiaries (pre-tax basis) ** | 5.5                     
|                                                                   |                         
|Total earnings as defined                                          | $179.6                  
|                                                                   |                         
|                                                                  
|FIXED CHARGES:                                                    
|Interest expense                                                   | $175.8                  
|Interest capitalized                                               | 3.4                     
|Estimated interest component of rent expense                       | 42.0                    
|Preferred dividend requirements of subsidiaries (pre-tax basis) ** | 5.5                     
|                                                                   |                         
|Total fixed charges as defined                                     | $226.7                  
|                                                                   |                         
|Ratio of Earnings to Fixed Charges (Unaudited) ***                 | 0.79                    
|                                                                   |                         

*In 2005, earnings as defined were
inadequate to cover fixed charges as defined by $47.1 million.

**Preferred dividend requirements
of subsidiaries (pre-tax basis) are computed by dividing the preferred dividend requirements
of subsidiaries by one hundred percent minus the annual effective income tax rate.

***The ratio calculation in the
above table relates to Alliant Energy Corporation's (Alliant Energy's) continuing
operations.  Refer to Note 16 of Alliant Energy's "Notes to Consolidated Financial
Statements" in Alliant Energy's Form 10-K for the annual period ended December 31, 2005
for information related to Alliant Energy's discontinued operations.