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 Dec. 31,
	2006		2005		2004		2003		2002
	(dollars in millions)
EARNINGS:
Net income	$172	.4	$165	.1	$125	.7	$100	.7	$90	.9
Income taxes	69	.4	80	.8	61	.7	71	.3	62	.3
Income before income taxes	241	.8	245	.9	187	.4	172	.0	153	.2
Fixed charges as defined	73	.3	72	.5	72	.3	69	.4	68	.1
Total earnings as defined	$315	.1	$318	.4	$259	.7	$241	.4	$221	.3
FIXED CHARGES:
Interest expense	$71	.8	$67	.7	$67	.9	$65	.4	$63	.7
Estimated interest component of rent expense	1	.5	4	.8	4	.4	4	.0	4	.4
Total fixed charges as defined	$73	.3	$72	.5	$72	.3	$69	.4	$68	.1
Ratio of Earnings to Fixed Charges	4.30		4.39		3.59		3.48		3.25
Preferred dividend requirements (pre-tax basis) (a)	$21	.6	$22	.9	$23	.0	$23	.2	$4	.9
Fixed charges and preferred dividend requirements	$94	.9	$95	.4	$95	.3	$92	.6	$73	.0
Ratio of Earnings to Combined Fixed Charges and
Preferred Dividend Requirements	3.32		3.34		2.73		2.61		3.03

(a) 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.