SOUTHWESTERN PUBLIC SERVICE COMPANY EXHIBIT 12. Statement of Computation of Ratio of Earnings Twelve Months Ended February 28, 1997 (Dollars In Thousands) Computation of Ratio of Earnings to Fixed Charges: Fixed charges, as defined: Interest on long-term debt $ 49,138 Amortization of debt premium, discount and expense 660 Other interest 6,377 Estimated interest factor of rental charges 1,245 Total fixed charges $ 57,420 Earnings as defined: Net earnings per statement of earnings $ 93,725 Fixed charges as shown 57,420 Income taxes: Federal-current 44,716 Federal-deferred 9,613 State 1,803 Investment tax credits (250) Earnings available for fixed charges $ 207,027 Ratio of earnings to fixed charges 3.61