Updated August 2, 2026. Quick answer: the FERS annuity supplement is your years of FERS service divided by 40, applied to the Social Security benefit you would get at 62. It bridges the gap between retiring and claiming Social Security, it is reduced by $1 for every $2 you earn over $24,480 (2026), and it stops for good at 62. Deferred and MRA+10 retirees never get it at all.
The calculator
The formula, in OPM’s words
“The numerator is the retiree’s total civilian service creditable under FERS, rounded to the nearest whole number, but not exceeding 40 years; and The denominator is 40.”
CSRS/FERS Handbook Chapter 51, Part 51A2, para D
This calculator reproduces OPM’s own published worksheet exactly. In OPM’s Example 1, a retiree with 33 years of FERS service and a $2,112 age-62 estimate gets a multiplier of .825000 and a supplement of $1,742 a month. Enter those two numbers above and you will get the same answer, to the dollar, including OPM’s rounding down.
The one input we cannot generate for you is the age-62 estimate. It is not the figure on your Social Security statement for full retirement age, and using that instead will overstate the supplement substantially.
Who gets it, and who never does
It goes to people who retire on an immediate, unreduced annuity before 62 — at the MRA with 30 years, at 60 with 20, or under the special provisions for law enforcement officers, firefighters, air traffic controllers and military reserve technicians.
It does not go to deferred retirees, and it does not go to MRA+10 retirees. That is worth pausing on, because MRA+10 is the retirement people slide into when they leave a few years early: taking it costs you both an age reduction and the supplement. Which door you leave through decides more than this one benefit.
The earnings test, and the trap inside it
Once it starts, the supplement is means-tested against work: “If a retiree’s earnings exceed the exempt amount, the annuity supplement will be reduced $1 for every $2 that is earned above that amount.” The exempt amount is the same one Social Security uses — $24,480 for 2026 — and it counts wages and self-employment income, not pension, annuity or investment income.
The trap is the timing. The reduction is assessed on the previous year’s earnings, so the money is usually docked a year after the work that triggered it, from someone who has forgotten the connection.
Special-provision retirees get a carve-out worth knowing: the reduction “does not apply to employees who retire under the special provisions … until they reach the MRA.” A federal firefighter who retires at 50 can work as much as they like for the years before their MRA without touching the supplement.
It ends at 62, whatever you do
OPM: the supplement is payable through “the last day of the month in which the retiree becomes age 62”. It does not convert into anything, and claiming Social Security early does not extend it. What actually happens at 62 is a decision about when to claim — 62 against 67 and the breakeven once you charge the money a return are the two halves of it.
Planning the whole picture rather than this one piece: whether the number works at all, and which account to draw first.
Formula, eligibility, earnings test, special-provision exception and end date from the OPM CSRS and FERS Handbook, Chapter 51 (Retiree Annuity Supplement); the 2026 exempt amount of $24,480 from SSA POMS RS 02501.025. Read August 2026. The exempt amount is indexed and changes annually. General information, not advice.