N.M. Admin. Code § 17.3.320.10
In order to insure proper accounting for accelerated amortization and liberalized depreciation a utility may take these allowances for tax purposes but shall continue to charge customary depreciation on the books. The utility shall make a further charge on the books equivalent to the tax reduction arising by reason of the allowances (instead of customary depreciation) and credit this to an accumulated deferred income tax account. After the allowance period, when the property has been fully amortized or depreciated through the application of accelerated amortization or liberalized depreciation, the reserve in the Accumulated Deferred Income Tax Account shall be used to pay taxes on that income in excess of the income which would have been derived had customary depreciation been utilized.
N.M. Admin. Code § 17.3.320.10