FERS Supplement Calculator

The FERS annuity supplement (OPM's formal name is the retiree annuity supplement) stands in for the Social Security benefit you cannot draw until 62. OPM estimates what your full-career benefit at 62 would be, then keeps only the part earned under FERS:

Supplement = benefit at 62 x (years of FERS civilian service / 40)

Years are rounded to the nearest whole year, with half a year rounded up, and never count for more than 40 (5 U.S.C. 8421(b)(3)). OPM rounds the monthly result down to the dollar. Military service is left out unless it was performed during leave without pay from a civilian job.

The supplement is paid through the earlier of the last day of the month in which you become 62 and the last day of the month before the first month you could get Social Security (5 CFR 842.503(c)). It stops whether or not you apply for Social Security.

For these rules you become 62 on the day before your 62nd birthday. In OPM's examples, Mary's birthday is September 1, so she becomes 62 on August 31 and her supplement ends on August 31. Sam's birthday is September 2; he can get Social Security from September, so his supplement also ends on August 31. With any later birthday in September, the last payment is for September.

If you work after retiring, OPM reduces the supplement, never the basic annuity, by $1 for every $2 you earn above the Social Security exempt amount. For 2026 that amount is $24,480 (SSA's figure for people under full retirement age, confirmed in OPM BAL 26-101). Earnings are wages plus net self-employment income, minus any net self-employment loss; your FERS annuity does not count.

The test looks back a year: excess earnings in one calendar year reduce the supplement for the 12 months starting in July of the next year (5 U.S.C. 8421a(b)(5)). Only earnings while you are entitled to the supplement count, and the reduction can never exceed the supplement paid in the year the money was earned. In OPM's example, Liza retires at the end of September with a $500 supplement; her 2020 payments total $1,500, so the reduction for her October to December earnings cannot exceed $1,500, however much she earned. In the year you turn 62, the excess is spread over the months still payable.

The supplement is not increased by cost-of-living adjustments (Handbook 51A4.1-1 C). OPM's 2026 COLA letter says the same: FERS COLAs apply only to the basic annuity, not the annuity supplement. The FERS basic annuity rose 2.0% on December 1, 2025 (CSRS 2.8%), but regular FERS retirees under 62 get no COLA at all; special provision retirees do.

So the supplement you start with is the amount you get until 62, apart from any earnings test reduction. Over several years, inflation lowers what it buys.

The supplement ends at 62 whether or not you claim Social Security then. To see your full FERS income, basic annuity and TSP included, use the FERS retirement calculator and the TSP calculator. To decide when to start Social Security after the supplement stops, try the Social Security break-even calculator.