How is the Special Retirement Supplement computed?
FERS employees only: The supplement is computed as if you were age 62 and eligible for a Social Security benefit when the supplement begins. By law, OPM first estimates what your full career (40 years) Social Security benefit would be. Then it calculates the amount of your civilian service under FERS and reduces the estimated full career Social Security benefit accordingly. For example, if your estimated full career Social Security benefit is $1,000 and you have worked five years under FERS, OPM will divide five by 40 (0.125) and multiply ($1,000 x 0.125 = $125). The result would be your Special Retirement Supplement, before any reductions.
