(a) Negotiated indirect cost rates based on a proposal later found to have included costs that:
(1) Are unallowable as specified by Federal statutes, regulations or the terms and conditions of a Federal award; or
(2) Are unallowable because they are not allocable to the Federal award(s), must be adjusted, or a refund must be made in accordance with the requirements of this section. These adjustments or refunds are intended to correct the proposals used to establish the rates and do not constitute a reopening of the rate negotiation. The adjustments or refunds must be made regardless of the type of rate negotiated (predetermined, final, fixed, or provisional).
(b) For rates covering a future fiscal year of the recipient or subrecipient, the unallowable costs must be removed from the indirect cost pools and the rates must be adjusted.
(c) For rates covering a past period, the Federal share of the unallowable costs must be computed for each year involved, and a cash refund (including interest) must be made to the Federal Government in accordance with the directions provided by the cognizant agency for indirect costs. When cash refunds are made for past periods covered by provisional or fixed rates, appropriate adjustments must be made when the rates are finalized to avoid duplicate recovery of the unallowable costs.
(d) For rates covering the current period, either a rate adjustment or a refund, as described in paragraphs (b) and (c) of this section, must be required by the cognizant agency for indirect costs. The choice of method must be at the discretion of the cognizant agency for indirect costs, based on its judgment as to which method would be most practical.
(e) The amount or proportion of unallowable costs included in each year's rate will be assumed to be the same as the amount or proportion of unallowable costs included in the base year proposal used to establish the rate.