(a) The Office shall promptly refund any amounts deducted under the authority of 5 U.S.C. 5514 when:   (1) The debt is waived or otherwise found not to be owing the United States (unless expressly prohibited by statute or regulation); or   (2) An administrative or judicial order directs the Office to make a refund.

(b) Unless required or permitted by law or contract, refunds under this subsection shall not bear interest.