plan sponsors are entitled to rely on— (1) a good faith interpretation of then existing administrative guidance for inadvertent benefit overpayment recoupments and recoveries that commenced before the date of enactment of this Act, and (2) determinations made before such date of enactment by the responsible plan fiduciary, in the exercise of its fiduciary discretion, not to seek recoupment or recovery of all or part of an inadvertent benefit overpayment. In the case of a benefit overpayment that occurred prior to the date of enactment of this Act, any installment payments by the participant or beneficiary to the plan or any reduction in periodic benefit payments to the participant or beneficiary, which were made in recoupment of such overpayment and which commenced prior to such date, may continue after such date. Nothing in this subsection shall relieve a fiduciary from responsibility for an overpayment that resulted from a breach of its fiduciary duties. 302. Reduction in excise tax on certain accumulations in qualified retirement plans (a) In general Subsection (a) of section 4974 of the Internal Revenue Code of 1986 is amended by striking 50 percent and inserting 25 percent . (b) Reduction in excise tax on failures To take required minimum distributions Section 4974 of such Code is amended by adding at the end the following new subsection: (e) Reduction of tax in certain cases (1) Reduction In the case of a taxpayer who— (A) corrects, during the correction window, a shortfall of distributions from an individual retirement plan which resulted in imposition of a tax under subsection (a), and (B) submits a return, during the correction window, reflecting such tax (as modified by this subsection), the first sentence of subsection (a) shall be applied by substituting 10 percent for 25 percent . (2) Correction window For purposes of this subsection, the term correction window means the period of time beginning on the date on which the tax under subsection (a) is imposed with respect to a shortfall of distributions