(a) General rule 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 (determined without regard to section
6420 (g)),
(2) under section
6421 (determined without regard to section
6421 (i)),1 and
(3) under section
6427 (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.
