Every person, at his election, shall be entitled to a deduction with respect to the amortization of the amortizable basis of any certified pollution control facility (as defined in subsection (d)), based on a period of 60 months. Such amortization deduction shall be an amount, with respect to each month of such period within the taxable year, equal to the amortizable basis of the pollution control facility at the end of such month divided by the number of months (including the month for which the deduction is computed) remaining in the period. Such amortizable basis at the end of the month shall be computed without regard to the amortization deduction for such month. The amortization deduction provided by this section with respect to any month shall be in lieu of the depreciation deduction with respect to such pollution control facility for such month provided by section
167. The 60-month period shall begin, as to any pollution control facility, at the election of the taxpayer, with the month following the month in which such facility was completed or acquired, or with the succeeding taxable year.