Allocable parental tax

For purposes of this subsection—

(A) In general The term “allocable parental tax” means the excess of— (i) the tax which would be imposed by this section on the parent’s taxable income if such income included the net unearned income of all children of the parent to whom this subsection applies, over (ii) the tax imposed by this section on the parent without regard to this subsection. For purposes of clause (i), net unearned income of all children of the parent shall not be taken into account in computing any exclusion, deduction, or credit of the parent.

(B) Child’s share A child’s share of any allocable parental tax of a parent shall be equal to an amount which bears the same ratio to the total allocable parental tax as the child’s net unearned income bears to the aggregate net unearned income of all children of such parent to whom this subsection applies.

(C) Special rule where parent has different taxable year Except as provided in regulations, if the parent does not have the same taxable year as the child, the allocable parental tax shall be determined on the basis of the taxable year of the parent ending in the child’s taxable year.