OPM Rule: Supplement = Social Security estimate at age 62 × (years of FERS civilian service ÷ 40), per OPM FERS Handbook Chapter 51. Military service credited to your annuity through a buyback deposit counts toward your basic annuity but is excluded from this calculation.
FERS Special Retirement Supplement Estimator
The supplement approximates the portion of Social Security you earned while under FERS, paid as a bridge from your retirement date until age 62.
Military buyback does not count here. Even if you paid a military deposit and had those years credited toward your basic FERS annuity, OPM excludes bought-back military service from the years used to compute the supplement. Enter only your actual civilian FERS-creditable years below.
From your Social Security Statement at ssa.gov/myaccount — use the age-62 estimate, not your full retirement age estimate.
Total civilian time under FERS, in years — you can use a decimal for partial years (e.g. 22 years 6 months = 22.5).
Disclaimer: This tool is for educational purposes only. It does not account for the Social Security earnings test, pro-rated supplements for retirements before minimum retirement age, or agency-specific rules for discontinued service or VERA/VSIP retirements. Always verify your supplement estimate with your agency HR office or OPM before making retirement decisions.