5 C.F.R. § 550.1616 – Corrective actions.

(a) Except at provided in paragraph (b) of this section, an error made in connection with the assignment of an agent's regular tour of duty (including any associated overtime supplement) must be corrected as soon as possible.
(b) A retroactive correction of a tour assignment (i.e., actual assigned work schedule as opposed to an error in the payroll system) may not be made in the following circumstances, unless CBP determines there exists, in connection with an agent's assigned tour, evidence of fraud, misrepresentation, fault, or lack of good faith on the part of the affected agent:
1. (1) Correction of an error in applying the consistency requirement described in §§ 550.1611(f)(5) and 550.1615; and
2. (2) Correction of an error that caused an employee to have a Level 1 regular tour of duty based solely on misapplication of the applicable percentage limitation described in §§ 550.1611(f)(4) and 550.1614.