Automatic advancement by step increases

§ 3552. Automatic advancement by step increases (a) Except as to a substitute employee in the Postal Transportation Service whose position is allocated to salary level PFS–5 as a distribution clerk in a railway or highway post office, each employee whose position is allocated to the Rural Carrier Schedule, the Fourth Class Office Schedule, or the Postal Field Service Schedule, who has not reached the highest step for his position, shall be advanced successively to the next higher step for his position at the beginning of the first pay period following the completion of each fifty-two calendar weeks of satisfactory service, if no equivalent increase in basic salary from any cause was received during the period of fifty-two calendar weeks. The benefit of successive step-increases shall be preserved, under regulations prescribed by the Postmaster General, for employees whose continuous service is interrupted by service in the Armed Forces. (b) Each substitute employee in the Postal Transportation Service, whose position is allocated to salary level PFS–5 as a distribution clerk in a railway or highway post office, shall be advanced in the manner prescribed for other employees under subsection (a) of this section, but may not be advanced beyond step four of salary level PFS–5.