Excess contributions treated as contribution made during subsequent year for which there is an unused limitation

(A) In general If for the taxable year the maximum amount allowable as a deduction under this section for contributions to an individual retirement plan exceeds the amount contributed, then the taxpayer shall be treated as having made an additional contribution for the taxable year in an amount equal to the lesser of— (i) the amount of such excess, or (ii) the amount of the excess contributions for such taxable year (determined under section 4973(b)(2) without regard to subparagraph (C) thereof).

(B) Amount contributed For purposes of this paragraph, the amount contributed— (i) shall be determined without regard to this paragraph, and (ii) shall not include any rollover contribution.

(C) Special rule where excess deduction was allowed for closed year Proper reduction shall be made in the amount allowable as a deduction by reason of this paragraph for any amount allowed as a deduction under this section for a prior taxable year for which the period for assessing deficiency has expired if the amount so allowed exceeds the amount which should have been allowed for such prior taxable year.