There shall be allowed as a credit against the tax imposed by this subtitle for the taxable year an amount equal to the sum of the amounts payable to the taxpayer—
(1)under section
6420 with respect to gasoline used during the taxable year on a farm for farming purposes (determined without regard to section
6420(g)),
(2)under section
6421 with respect to gasoline used during the taxable year
(A) otherwise than as a fuel in a highway vehicle or
(B) in vehicles while engaged in furnishing certain public passenger land transportation service (determined without regard to section
6421(i)),[1] and
(3)under section
6427 with respect to fuels used for nontaxable purposes or resold during the taxable year (determined without regard to section
6427(k)).
(b) Exception
Credit shall not be allowed under subsection (a) for any amount payable under section
6421 or
6427, if a claim for such amount is timely filed and, under section
6421(i) or
6427(k), is payable under such section.