Exhibit 12.3

WISCONSIN POWER AND LIGHT COMPANY

RATIO OF EARNINGS TO FIXED CHARGES AND RATIO OF EARNINGS TO COMBINED FIXED CHARGES
      AND PREFERRED DIVIDEND REQUIREMENTS

|                                                    | Nine Months           |      |                     
|--------------------------------------------------- | --------------------- | ---- | --------------------
|                                                    | Ended Sep. 30,        |      | Years Ended Dec. 31,
|                                                    |                       |      |                     
|                                                    | 2008                  | 2007 |                     
|                                                    |                       |      |                     
|                                                    | (dollars in millions)
|EARNINGS:                                           |                       |      |                     
|Net income                                          |                       | $94  | .1                  
|Income taxes (a)                                    |                       | 54   | .1                  
|                                                    |                       |      |                     
|Income before income taxes                          |                       | 148  | .2                  
|                                                   
|Fixed charges as defined                            |                       | 69   | .0                  
|                                                   
|Adjustment for undistributed equity earnings        |                       | (4   | .0)                 
|                                                    |                       |      |                     
|Total earnings as defined                           |                       | $213 | .2                  
|                                                    |                       |      |                     
|FIXED CHARGES:                                      |                      
|Interest expense                                    |                       | $44  | .5                  
|Estimated interest component of rent expense        |                       | 24   | .5                  
|                                                    |                       |      |                     
|Total fixed charges as defined                      |                       | $69  | .0                  
|                                                    |                       |      |                     
|Ratio of Earnings to Fixed Charges                  |                       | 3    | .09                 
|                                                    |                       |      |                     
|Preferred dividend requirements (pre-tax basis) (b) |                       | $3   | .9                  
|                                                    |                       |      |                     
|Fixed charges and preferred dividend requirements   |                       | $72  | .9                  
|                                                    |                       |      |                     
|Ratio of Earnings to Combined Fixed Charges and     |                      
|Preferred Dividend Requirements                     |                       | 2    | .92                 
|                                                    |                       |      |                     

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

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