In general

In the case of an individual to whom this paragraph applies for the taxable year, the limitation of paragraph (1) of subsection (b) shall be equal to the lesser of—

(A) the dollar amount in effect under subsection (b)(1)(A) for the taxable year, or

(B) the sum of— (i) the compensation includible in such individual’s gross income for the taxable year, plus (ii) the compensation includible in the gross income of such individual’s spouse for the taxable year reduced by— (I) the amount allowed as a deduction under subsection (a) to such spouse for such taxable year, (II) the amount of any designated nondeductible contribution (as defined in section 408( o )) on behalf of such spouse for such taxable year, and (III) the amount of any contribution on behalf of such spouse to a Roth IRA under section 408A for such taxable year.