12 CFR §1073.310

1. (a)Where the Bureau is the creditor agency, it shall promptly refund any amount deducted under the authority of 5 U.S.C. 5514 when the debt is waived or otherwise found not to be owing to the United States (unless expressly prohibited by statute or regulation), or when an administrative or judicial order directs the Bureau to refund amounts deducted from the employee's current pay.
2. (b)Unless required by law or contract, such refunds shall not bear interest.