Part time credit toward retirement annuity
Under CSRS/CSRS-Offset and FERS, the high-three average salary used for part-time work is the salary that would have been paid if the employee had worked full-time, and the basic benefit formula is the same. However, the calculation is adjusted by a factor determined by dividing the actual hours worked by the full-time hours available over the creditable federal service time.
Until enactment of PL 111-84, which was effective with retirements on or after October 28, 2009, annuities for CSRS/CSRS Offset benefits, including time under CSRS for FERS employees eligible for mixed FERS-CSRS annuities, were calculated under two separate methods, differing for service before April 7, 1986 versus service from that date forward. Under the prior policy, years of part-time service might not have been used for determining the high-three average salary, even though the hourly salary in those years might have been among the highest three. PL 111-84 required OPM to calculate annuities under CSRS based on the highest three average pay for the position he or she occupied regardless of when.