Exhibit 12.1
ALLIANT ENERGY CORPORATION
RATIO OF EARNINGS TO FIXED CHARGES

| Years Ended December 31,
| 2012 | 2011 | 2010 | 2009 | 2008
| (dollars in millions)
EARNINGS: |  |  |  |  |
Net income from continuing operations attributable to Alliant Energy Corporation common shareowners |  | $324.9 |  |  | $323.1 |  |  | $291.5 |  |  | $111.6 |  |  | $265.8 |
Income tax expense (benefit) (a) | 89.4 |  | 69.2 |  | 147.7 |  | (6.8 | ) | 130.6 |
Subtotal | 414.3 |  | 392.3 |  | 439.2 |  | 104.8 |  | 396.4 |
Fixed charges as defined | 208.0 |  | 208.4 |  | 215.4 |  | 199.7 |  | 185.2 |
Adjustment for undistributed equity earnings | (7.1 | ) | (7.0 | ) | (5.9 | ) | (6.7 | ) | (6.1 | )
Less: |  |  |  |  |
Interest capitalized | 6.1 |  | 2.7 |  | — |  | — |  | — |
Preferred dividend requirements of subsidiaries (pre-tax basis) (b) | 20.1 |  | 22.0 |  | 27.6 |  | 17.7 |  | 27.3 |
Total earnings as defined |  | $589.0 |  |  | $569.0 |  |  | $621.1 |  |  | $280.1 |  |  | $548.2 |
FIXED CHARGES: |  |  |  |  |
Interest expense |  | $156.7 |  |  | $158.3 |  |  | $162.8 |  |  | $154.8 |  |  | $125.8 |
Interest capitalized | 6.1 |  | 2.7 |  | — |  | — |  | — |
Estimated interest component of rent expense | 25.1 |  | 25.4 |  | 25.0 |  | 27.2 |  | 32.1 |
Preferred dividend requirements of subsidiaries (pre-tax basis) (b) | 20.1 |  | 22.0 |  | 27.6 |  | 17.7 |  | 27.3 |
Total fixed charges as defined |  | $208.0 |  |  | $208.4 |  |  | $215.4 |  |  | $199.7 |  |  | $185.2 |
Ratio of Earnings to Fixed Charges (c) | 2.83 |  | 2.73 | 2.88 | 1.40 | 2.96

(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 annual effective income tax rate.
(c) The ratio calculation in the above table relates to Alliant Energy Corporation’s continuing operations.