5 CFR § 1639.29
Refunds
November 4, 2020
(a) If the Board is the creditor agency, it will promptly refund any amount deducted under the authority of 5 U.S.C. 5514, when:
(1) The debt is waived or all or part of the funds deducted are otherwise found not to be owed; or
(2) An administrative or judicial order directs the Board to make a refund.
(b) Unless required or permitted by law or contract, refunds under this section will not bear interest.