SOUTHWESTERN PUBLIC SERVICE COMPANY EXHIBIT 12. Statement of Computation of Ratio of Earnings Twelve Months Ended November 30, 1996 (Dollars In Thousands) Computation of Ratio of Earnings to Fixed Charges: Fixed charges, as defined: Interest on long-term debt ....................................................... $ 46,801 Amortization of debt premium, discount and expense ............................... 616 Other interest ................................................................... 7,190 Estimated interest factor of rental charges ...................................... 1,245 Total fixed charges ............................................ $ 55,852 Earnings as defined: Net earnings per statement of earnings ........................................... $ 104,073 Fixed charges as shown ........................................................... 55,852 Income taxes: Federal-current ......................................................... 44,417 Federal-deferred ........................................................ 16,794 State ................................................................... 2,345 Investment tax credits ........................................................... (250) Earnings available for fixed charges ............................................. $ 223,231 Ratio of earnings to fixed charges ........................................................ 4.00 Computation of Ratio of Earnings to Fixed Charges and Preferred Dividend Requirements Combined: Total fixed charges, as shown above ....................................................... $ 55,852 Preferred dividend requirements* .......................................................... 2,044 Total fixed charges and preferred dividend requirements combined $ 57,896 Earnings available for fixed charges and preferred dividend requirements combined ............................................................ $ 223,231 Ratio of earnings to fixed charges and preferred dividend requirements combined ............................................................ 3.86 *Preferred dividend requirements: Annual preferred dividend requirement .......................... $ 1,274 Less amount deductible for income tax purposes ................. 7 Net requirement [A] .................................... $ 1,267 1 / (100% - effective tax rate) [B] ............................ 1.608 Effective tax rate ............................................. 37.8% [A] x [B] ...................................................... $ 2,037 Add amount deductible for income tax purposes .................. 7 Preferred dividend requirements ................................ $ 2,044