14 C.F.R. § 1261.605 – Refunds.

(a) NASA will promptly refund to the employee amounts paid or deducted under this subpart when:
1. (1) A debt is waived or otherwise found not owing the United States (unless expressly prohibited by statute or regulation); or
2. (2) The employee's paying agency is directed by an administrative or judicial order to refund amounts deducted from his or her current pay.
(b) Refunds are not to bear any interest unless the law applicable to that particular debt specifically requires or permits a stated interest amount on refunds.