SOUTHWESTERN PUBLIC SERVICE COMPANY EXHIBIT 12. Statement of Computation of Ratio of Earnings Twelve Months Ended May 31, 1996 (Dollars In Thousands) Computation of Ratio of Earnings to Fixed Charges: Fixed charges, as defined: Interest on long-term debt ....................................................... $ 43,911 Amortization of debt premium, discount and expense ............................... 561 Other interest ................................................................... 5,572 Estimated interest factor of rental charges ...................................... 1,292 Total fixed charges ............................................ $ 51,336 Earnings as defined: Net earnings per statement of earnings ........................................... $114,329 Fixed charges as shown ........................................................... 51,336 Income taxes: Federal-current ......................................................... 53,542 Federal-deferred ........................................................ 13,987 State ................................................................... 2,436 Investment tax credits ........................................................... (250) Earnings available for fixed charges ............................................. $235,380 Ratio of earnings to fixed charges ........................................................ 4.59 Computation of Ratio of Earnings to Fixed Charges and Preferred Dividend Requirements Combined: Total fixed charges, as shown above ....................................................... $ 51,336 Preferred dividend requirements* .......................................................... 5,949 Total fixed charges and preferred dividend requirements combined $ 57,285 Earnings available for fixed charges and preferred dividend requirements combined ............................................................ $235,380 Ratio of earnings to fixed charges and preferred dividend requirements combined ............................................................ 4.11 *Preferred dividend requirements: Annual preferred dividend requirement .......................... $ 3,713 Less amount deductible for income tax purposes ................. 48 Net requirement [A] .................................... $ 3,665 1 / (100% - effective tax rate) [B] ............................ 1.610 Effective tax rate ............................................. 37.9% [A] x [B] ...................................................... $ 5,901 Add amount deductible for income tax purposes .................. 48 Preferred dividend requirements ................................ $ 5,949