41 C.F.R. § 105-72.803 – Collection of amounts due.

(a) Any funds paid to a recipient in excess of the amount to which the recipient is finally determined to be entitled under the terms and conditions of the award constitute a debt to the Federal Government. If not paid within a reasonable period after the demand for payment, the Federal awarding agency may reduce the debt by paragraph (a) (1), (2) or (3) of this section.
1. (1) Making an administrative offset against other requests for reimbursements.
2. (2) Withholding advance payments otherwise due to the recipient.
3. (3) Taking other action permitted by statute.
(b) Except as otherwise provided by law, the Federal awarding agency shall charge interest on an overdue debt in accordance with 4 CFR Chapter II, Federal Claims Collection Standards.