§ 5535 — Extra Pay For Details Prohibited

(a) An officer may not receive pay in addition to the pay for his regular office for performing the duties of a vacant office as authorized by sections 3345–3347 of this title. (b) An employee may not receive— (1) additional pay or allowances for performing the duties of another employee; or (2) pay in addition to the regular pay received for employment held before his appointment or designation as acting for or instead of an occupant of another position or employment.