2 C.F.R. § 200.425
(a) A reasonably proportionate share of the costs of audits required by and performed in accordance with the Single Audit Act Amendments of 1996 (31 U.S.C. 7501-7507), and the requirements of this part are allowable. However, the following audit costs are unallowable:
(c) Pass-through entities may charge Federal awards for the cost of agreed-upon procedures engagements to monitor subrecipients (in accordance with §§ 200.331-333) exempt from having an audit conducted under the Single Audit Act and the requirements of this part. This cost is allowable only if the agreed-upon procedures engagements are: