45 CFR 33.1 - Purpose, authority, and scope.
(2) The procedures contained in this part do not apply to any case where an employee consents to collection through deduction(s) from the employee's pay account, or to debts arising under the Internal Revenue Code or the tariff laws of the United States, or where another statute explicitly provides for, or prohibits, collection of a debt by salary offset (e.g., travel advances in 5 U.S.C. 5705 and employee training expenses in 5 U.S.C. 4108).
(3) This part does not preclude an employee from requesting waiver of an erroneous payment under 5 U.S.C. 5584, 10 U.S.C. 2774, or 32 U.S.C. 716, or in any way questioning the amount or validity of a debt, in the manner prescribed by the Secretary. Similarly, this part does not preclude an employee from requesting waiver of the collection of a debt under any other applicable statutory authority.