nondeductible contributions
(1) In general The term “nondeductible contributions” means, with respect to any qualified employer plan, the sum of— (A) the excess (if any) of— (i) the amount contributed for the taxable year by the employer to or under such plan, over (ii) the amount allowable as a deduction under section 404 for such contributions (determined without regard to subsection (e) thereof), and (B) the amount determined under this subsection for the preceding taxable year reduced by the sum of— (i) the portion of the amount so determined returned to the employer during the taxable year, and (ii) the portion of the amount so determined deductible under section 404 for the taxable year (determined without regard to subsection (e) thereof).