The Secretary may prescribe regulations providing for the crediting against the tax imposed by this subtitle of the amount determined by the taxpayer or the Secretary to be allowable under section 6413(c) as a special refund of tax imposed on wages. The amount allowed as a credit under such regulations shall, for purposes of this subtitle, be considered an amount withheld at source as tax under section 3402.
Any amount to which paragraph (1) applies shall be allowed as a credit for the taxable year beginning in the calendar year during which the wages were received. If more than one taxable year begins in the calendar year, such amount shall be allowed as a credit for the last taxable year so beginning.
Any credit allowed by subsection (a) for any amount withheld under section 3406 shall be allowed for the taxable year of the recipient of the income in which the income is received.