In general

If, for any taxable year, any amount is excluded from gross income of a taxpayer under subsection (a), then, notwithstanding sections 1 and 55—

(A) if such taxpayer has taxable income for such taxable year, the tax imposed by section 1 for such taxable year shall be equal to the excess (if any) of— (i) the tax which would be imposed by section 1 for such taxable year if the taxpayer’s taxable income were increased by the amount excluded under subsection (a) for such taxable year, over (ii) the tax which would be imposed by section 1 for such taxable year if the taxpayer’s taxable income were equal to the amount excluded under subsection (a) for such taxable year, and

(B) if such taxpayer has a taxable excess (as defined in section 55(b)(1)(B)) for such taxable year, the amount determined under the first sentence of section 55(b)(1)(A) for such taxable year shall be equal to the excess (if any) of— (i) the amount which would be determined under such sentence for such taxable year (subject to the limitation of section 55(b)(3)) if the taxpayer’s taxable excess (as so defined) were increased by the amount excluded under subsection (a) for such taxable year, over (ii) the amount which would be determined under such sentence for such taxable year if the taxpayer’s taxable excess (as so defined) were equal to the amount excluded under subsection (a) for such taxable year.

For purposes of this paragraph, the amount excluded under subsection (a) shall be reduced by the aggregate amount of any deductions or exclusions disallowed under subsection (d)(6) with respect to such excluded amount.