Exhibit 12.2
INTERSTATE POWER AND LIGHT COMPANY
RATIO OF EARNINGS TO FIXED CHARGES AND RATIO OF EARNINGS TO COMBINED FIXED CHARGES AND PREFERRED DIVIDEND REQUIREMENTS

| Years Ended December 31,
| 2012 | 2011 | 2010 | 2009 | 2008
| (dollars in millions)
EARNINGS: |  |  |  |  |
Net income |  | $150.2 |  |  | $139.3 |  |  | $143.4 |  |  | $153.0 |  |  | $141.6 |
Income tax expense (benefit) (a) | (19.8 | ) | (3.6 | ) | 42.3 |  | 27.0 |  | 52.6 |
Income before income taxes | 130.4 |  | 135.7 |  | 185.7 |  | 180.0 |  | 194.2 |
Fixed charges as defined | 79.3 |  | 79.6 |  | 83.1 |  | 77.5 |  | 63.7 |
Total earnings as defined |  | $209.7 |  |  | $215.3 |  |  | $268.8 |  |  | $257.5 |  |  | $257.9 |
FIXED CHARGES: |  |  |  |  |
Interest expense |  | $78.5 |  |  | $78.7 |  |  | $82.2 |  |  | $76.5 |  |  | $61.9 |
Estimated interest component of rent expense | 0.8 |  | 0.9 |  | 0.9 |  | 1.0 |  | 1.8 |
Total fixed charges as defined |  | $79.3 |  |  | $79.6 |  |  | $83.1 |  |  | $77.5 |  |  | $63.7 |
Ratio of Earnings to Fixed Charges | 2.64 |  | 2.70 |  | 3.23 |  | 3.32 |  | 4.05 |
Preferred dividend requirements (pre-tax basis) (b) |  | $10.9 |  |  | $14.6 |  |  | $19.9 |  |  | $18.1 |  |  | $21.1 |
Fixed charges and preferred dividend requirements |  | $90.2 |  |  | $94.2 |  |  | $103.0 |  |  | $95.6 |  |  | $84.8 |
Ratio of Earnings to Combined Fixed Charges and Preferred Dividend Requirements | 2.32 |  | 2.29 |  | 2.61 |  | 2.69 |  | 3.04 |

(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 annual effective income tax rate.