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

|                                                    | Six Months            |        |                     
|--------------------------------------------------- | --------------------- | ------ | --------------------
|                                                    | Ended June 30,        |        | Years Ended Dec. 31,
|                                                    |                       |        |                     
|                                                    | 2009                  | 2008   |                     
|                                                    |                       |        |                     
|                                                    | (dollars in millions)
|EARNINGS:                                           |                      
|Net income                                          |                       | $42.9  |                     
|Income taxes (a)                                    |                       | 20.1   |                     
|                                                    |                       |        |                     
|Income before income taxes                          |                       | 63.0   |                     
|Fixed charges as defined                            |                       | 47.3   |                     
|Adjustment for undistributed equity earnings        |                       | (3.7)  |                     
|                                                    |                       |        |                     
|Total earnings as defined                           |                       | $106.6 |                     
|                                                    |                       |        |                     
|FIXED CHARGES:                                      |                      
|Interest expense                                    |                       | $34.7  |                     
|Estimated interest component of rent expense        |                       | 12.6   |                     
|                                                    |                       |        |                     
|Total fixed charges as defined                      |                       | $47.3  |                     
|                                                    |                       |        |                     
|Ratio of Earnings to Fixed Charges                  |                       | 2.25   |                     
|                                                    |                       |        |                     
|Preferred dividend requirements (pre-tax basis) (b) |                       | $2.5   |                     
|                                                    |                       |        |                     
|Fixed charges and preferred dividend requirements   |                       | $49.8  |                     
|                                                    |                       |        |                     
|Ratio of Earnings to Combined Fixed Charges and     |                      
|Preferred Dividend Requirements                     |                       | 2.14   |                     
|                                                    |                       |        |                     

(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.