| Exhibit      12.1                                                                                                                            |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |
|----------------------------------------------------------------------------------------------------------------------------------------------|--------|----------------------------|--------|--------|--------|--------|--------|--------|--------|--------|--------|--------|--------|-------------|--------|
|                                                                                                                                         |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |
| ALLIANT      ENERGY CORPORATION                                                                                                              |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |
|                                                                                                                                         |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |
| RATIO      OF EARNINGS TO FIXED CHARGES                                                                                                      |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |
|                                                                                                                                         |   | Years Ended Dec.      31,  |   |
|                                                                                                                                         |   | 2009                       |   |   | 2008   |   |   | 2007   |   |   | 2006   |   |   | 2005    (a) |   |
|                                                                                                                                         |   | (dollars in      millions) |   |
| EARNINGS:                                                                                                                                    |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |
| Net      income from continuing operations attributable to                                                                                   |   |                       |   |   |   |   |   |   |   |   |   |   |   |
|    Alliant      Energy Corporation common shareowners                                                                         |   | $                          | 110.7  |   |   | $      | 280.0  |   |   | $      | 424.7  |   |   | $           | 338.3  |   |   | $ | 56.4 |   |
| Income tax expense      (benefit) (b)                                                                                                        |   |                       | (9.2   | )      |   |   | 140.2  |   |   |   | 255.8  |   |   |        | 203.0  |   |   |   | (52.9 | ) |
| Subtotal                                                                                                                                     |   |                       | 101.5  |   |   |   | 420.2  |   |   |   | 680.5  |   |   |        | 541.3  |   |   |   | 3.5 |   |
|                                                                                                                                         |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |   |   |   |   |   |
| Fixed charges as      defined                                                                                                                |   |                       | 200.7  |   |   |   | 186.5  |   |   |   | 185.6  |   |   |        | 213.4  |   |   |   | 226.7 |   |
|                                                                                                                                         |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |   |   |   |   |   |
| Adjustment for      undistributed equity earnings                                                                                            |   |                       | (6.7   | )      |   |   | (6.1   | )      |   |   | (7.8   | )      |   |        | (16.6  | ) |   |   | (41.7 | ) |
|                                                                                                                                         |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |   |   |   |   |   |
| Less:                                                                                                                                        |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |   |   |   |   |   |
|    Interest      capitalized                                                                                                  |   |                       | -      |   |   |   | -      |   |   |   | -      |   |   |        | -      |   |   |   | 3.4 |   |
|    Preferred      dividend requirements of subsidiaries (pre-tax basis) (c)                                                   |   |                       | 17.4   |   |   |   | 27.5   |   |   |   | 29.5   |   |   |        | 29.3   |   |   |   | 5.5 |   |
|                                                                                                                                         |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |   |   |   |   |   |
| Total earnings as      defined                                                                                                               |   | $                          | 278.1  |   |   | $      | 573.1  |   |   | $      | 828.8  |   |   | $           | 708.8  |   |   | $ | 179.6 |   |
|                                                                                                                                         |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |   |   |   |   |   |
| FIXED      CHARGES:                                                                                                                          |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |   |   |   |   |   |
| Interest      expense                                                                                                                        |   | $                          | 154.9  |   |   | $      | 125.8  |   |   | $      | 116.7  |   |   | $           | 145.7  |   |   | $ | 175.8 |   |
| Interest      capitalized                                                                                                                    |   |                       | -      |   |   |   | -      |   |   |   | -      |   |   |        | -      |   |   |   | 3.4 |   |
| Estimated interest      component of rent expense                                                                                            |   |                       | 28.4   |   |   |   | 33.2   |   |   |   | 39.4   |   |   |        | 38.4   |   |   |   | 42.0 |   |
| Preferred dividend      requirements of subsidiaries (pre-tax basis) (c)                                                                     |   |                       | 17.4   |   |   |   | 27.5   |   |   |   | 29.5   |   |   |        | 29.3   |   |   |   | 5.5 |   |
| Total fixed charges      as defined                                                                                                          |   | $                          | 200.7  |   |   | $      | 186.5  |   |   | $      | 185.6  |   |   | $           | 213.4  |   |   | $ | 226.7 |   |
|                                                                                                                                         |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |   |   |   |   |   |
| Ratio of Earnings to      Fixed Charges (d)                                                                                                  |   |                       | 1.39   |   |   |   | 3.07   |   |   |   | 4.47   |   |   |        | 3.32   |   |   |   | 0.79 |   |
|                                                                                                                                         |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |   |   |   |   |   |
| (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 taxbenefits.                                                                          |   |                       |   |   |   |   |   |   |   |   |   |   |   |
|                                                                                                                                         |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |   |   |   |   |   |
| (c)      Preferred dividend requirements of subsidiaries (pre-tax basis) are      computed by dividing the preferred dividend requirementsof |   |
| subsidiaries by one      hundred percent minus the respective annual effective income tax      rate.                                         |   |
|                                                                                                                                         |   |                       |   |   |   |   |   |   |   |   |   |   |   |        |   |   |   |   |   |   |
| (d) The ratio      calculation in the above table relates to Alliant Energy Corporation's      continuing operations.                   |   |