5 CFR 841.507 - Correction of unjustified or unwarranted personnel action.
(a) When an “appropriate authority” determines that there has been an “unjustified or unwarranted personnel action” as these terms are defined in subpart H of part 550 of this title, the employing agency will pay the Fund the amount of the normal cost percentage of the basic pay included in back pay. The normal cost percentage owed the Fund is computed on the amount of gross basic pay without regard to deductions described in § 550.805(e) of this chapter for other amounts earned or erroneous payments received.
(1) Any FERS benefits - lump-sum payments or annuity benefits - paid based on a separation that is later cancelled are considered erroneous payments that must be repaid to OPM. Agencies must deduct such payments from any back pay adjustment to which the employee may be entitled as required by 5 CFR 550.805(e).
(2) Amounts recovered from back pay will not be subject to waiver consideration under 5 U.S.C. 8470(b). If there is no back pay, or the back pay is insufficient to recover the entire erroneous payment, the employee may request that OPM waive recovery of the uncollected portion of the overpayment. If waiver is not granted, the employee must repay the erroneous payment.