Exhibit 12.1
ALLIANT ENERGY CORPORATION
RATIO OF EARNINGS TO FIXED CHARGES

| Nine Months Ended |  |  |  |  |  |
| September 30, |  | Years Ended December 31,
| 2012 |  | 2011 |  | 2011 | 2010 | 2009 | 2008 | 2007
| (dollars in millions)
EARNINGS: |  |  |  |  |  |  |  |  |
Net income from continuing operations attributable to Alliant Energy Corporation common shareowners |  | $253.8 |  |  |  | $259.2 |  |  |  | $323.1 |  |  | $291.5 |  |  | $111.6 |  |  | $265.8 |  |  | $415.7 |
Income tax expense (benefit) (a) | 83.8 |  |  | 54.5 |  |  | 69.0 |  | 147.6 |  | (6.8 | ) | 130.6 |  | 249.9 |
Subtotal | 337.6 |  |  | 313.7 |  |  | 392.1 |  | 439.1 |  | 104.8 |  | 396.4 |  | 665.6 |
Fixed charges as defined | 158.7 |  |  | 160.3 |  |  | 208.4 |  | 215.4 |  | 199.7 |  | 185.2 |  | 184.6 |
Adjustment for undistributed equity earnings | (4.7 | ) |  | (5.2 | ) |  | (7.0 | ) | (5.9 | ) | (6.7 | ) | (6.1 | ) | (7.8 | )
Less: |  |  |  |  |  |  |  |  |
Interest capitalized | 5.1 |  |  | 1.3 |  |  | 2.7 |  | — |  | — |  | — |  | — |
Preferred dividend requirements of subsidiaries (pre-tax basis) (b) | 15.7 |  |  | 17.1 |  |  | 22.0 |  | 27.6 |  | 17.7 |  | 27.3 |  | 29.5 |
Total earnings as defined |  | $470.8 |  |  |  | $450.4 |  |  |  | $568.8 |  |  | $621.0 |  |  | $280.1 |  |  | $548.2 |  |  | $812.9 |
FIXED CHARGES: |  |  |  |  |  |  |  |  |
Interest expense |  | $115.8 |  |  |  | $119.7 |  |  |  | $158.3 |  |  | $162.8 |  |  | $154.8 |  |  | $125.8 |  |  | $116.7 |
Interest capitalized | 5.1 |  |  | 1.3 |  |  | 2.7 |  | — |  | — |  | — |  | — |
Estimated interest component of rent expense | 22.1 |  |  | 22.2 |  |  | 25.4 |  | 25.0 |  | 27.2 |  | 32.1 |  | 38.4 |
Preferred dividend requirements of subsidiaries (pre-tax basis) (b) | 15.7 |  |  | 17.1 |  |  | 22.0 |  | 27.6 |  | 17.7 |  | 27.3 |  | 29.5 |
Total fixed charges as defined |  | $158.7 |  |  |  | $160.3 |  |  |  | $208.4 |  |  | $215.4 |  |  | $199.7 |  |  | $185.2 |  |  | $184.6 |
Ratio of Earnings to Fixed Charges (c) | 2.97 |  |  | 2.81 |  |  | 2.73 |  | 2.88 |  | 1.40 |  | 2.96 |  | 4.40 |

(a) Includes net interest related to unrecognized tax benefits.
(b) 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.
(c) The ratio calculation in the above table relates to Alliant Energy Corporation's continuing operations.