(a) Beginning with the taxable year after December 31, 2013, through the taxable year ending December 31, 2026, there shall be allowed against the tax imposed by § 47-1808.03 a credit in the amount of 50% of the equipment and labor costs directly attributable to the cost to convert a motor vehicle licensed in the District that operates on petroleum diesel or petroleum derived gasoline to a motor vehicle that operates on an alternative fuel. (b) The credit claimed under this section in any one tax year may not exceed the taxpayer’s tax liability under § 47-1808.03 for that year. The credit shall not be refundable. (c) For the purposes of this section, the term “alternative fuel” shall have the same meaning as provided in § 47-1806.12(f)(1).