FERS Supplement Calculator

FERS annuity supplement

What the FERS supplement is

OPM explains that FERS employees who retire after age 62 are generally eligible for their FERS annuity, their Thrift Savings Plan benefits and their Social Security benefits. Social Security retirement benefits can start as early as 62, so someone who retires earlier has a gap. If you are eligible to retire before 62 and are not yet eligible for Social Security, you are generally entitled instead to a FERS annuity supplement. It is part of your FERS annuity and is meant to replace the amount of the Social Security benefit you would have otherwise received had you retired after 62.

OPM's handbook describes the supplement as an approximation of the value of your FERS service in a Social Security benefit, not your whole Social Security benefit. It is paid monthly as part of your annuity until about 62, it is not increased by cost-of-living adjustments, and after you reach your minimum retirement age it can be reduced if you earn too much from work.

How the supplement is calculated

OPM's formula has two steps. First it estimates the Social Security benefit you would get at 62 for a full career. Then it multiplies that amount by your years of FERS civilian service divided by 40. OPM's example: an estimated benefit of $1,000 and 30 years under FERS gives 30 / 40 = 0.75, so the supplement is $750 a month before any reductions. The statute rounds your service to the nearest whole year, with a half year rounded up, and caps the numerator at 40 (5 U.S.C. 8421). OPM's worksheet rounds the monthly result down to the next lower dollar.

Military service does not count in the years, with one exception: OPM counts active military service performed while you were on military leave with or without pay from a civilian position, as long as the military deposit is paid under USERRA rules.

Sources: OPM, FERS types of retirement; OPM, CSRS and FERS Handbook, chapter 51 (March 2022), worksheets for examples 1 to 3. The calculator reproduces all four results.

Your Social Security estimate versus OPM's figure

OPM computes the Social Security part itself. It builds an earnings history from actual and deemed pay, where actual pay is only basic pay subject to FERS retirement deductions, computes the benefit as if you were 62 and fully insured on January 1 of the year the supplement begins, applies the age 62 reduction, and does not apply the windfall elimination provision. Your Social Security Statement shows personalized benefit estimates at nine different ages, and its age 62 figure is the closest number most people have. The handbook points out the key difference: Social Security counts all of a worker's years of employment, not just federal service, so OPM's figure can be higher or lower than the estimate you enter.

Who can get the supplement

You may be eligible if you retire voluntarily on an immediate annuity that is not reduced for age: at your minimum retirement age (MRA) with 30 years of service, or at 60 with 20 years. Special provision retirees, such as law enforcement officers and firefighters, can receive it right away; in OPM's handbook example, a firefighter who retired at 52 started receiving the supplement immediately. If you retire involuntarily before your MRA, or voluntarily during a major reorganization or reduction in force, the supplement waits until you reach your MRA.

There is no supplement with a deferred annuity, a disability retirement or an immediate MRA+10 retirement, and none if you retire at 62 or older. You also need at least one full calendar year of service subject to FERS computation rules.

Source: OPM, FERS eligibility (minimum retirement age chart).

When the supplement starts and stops

An annuity under the regular FERS retirement provisions begins on the first day of the month after you separate (5 U.S.C. 8464), and the supplement is paid with it. For early and involuntary retirements, where the supplement waits for your MRA, the calculator counts payments from the first full month after you reach it.

The supplement ends on the earlier of two dates: the last day of the month before the first month you would be entitled to Social Security, or the last day of the month in which you reach 62. For these rules you reach 62 on the day before your 62nd birthday. OPM's handbook gives two examples. Mary's 62nd birthday is September 1, so her supplement stops on August 31. Sam's birthday is September 2; he can get Social Security for September, so his supplement also stops on August 31, although it would run through September 30 if he were not entitled to Social Security.

In the default example, a FERS employee born May 15, 1968 reaches the MRA of 56 and 8 months in January 2025 and retires on December 31, 2026 with 30 years of service. A Social Security estimate of $1,900 at 62 gives $1,900 x 30 / 40 = $1,425 a month. The supplement runs from January 2027 through May 2030, 41 payments worth $58,425 before any earnings test.

The earnings test

Once you reach your MRA, the supplement is reduced by $1 for every $2 you earn above the Social Security annual exempt amount, which is $24,480 in 2026. OPM uses the same exempt amount as Social Security. Earnings means wages plus net earnings from self-employment, minus any net loss from self-employment; your FERS annuity itself does not count. The test looks back: excess earnings in one year reduce the supplement paid in the 12 months that begin in July of the following year (5 U.S.C. 8421a), and the reduction can never be more than the supplement itself.

Only earnings from the period when you are entitled to the supplement count. Take a retiree who already receives a $1,425 supplement and earns $40,000 from a new job during all of 2026. The earnings are $15,520 over the exempt amount, so half of that, $7,760, comes off the supplement from July 2027 through June 2028, which is $646.67 a month. Special provision retirees are not subject to the test until they reach their MRA. If you receive the supplement after your MRA, you report your earnings to OPM each year on form RI 92-22. The same exempt amount appears in our Social Security earnings test calculator, which applies if you claim Social Security before full retirement age.

Our calculation for a $1,425 monthly supplement at the 2026 exempt amount of $24,480 (SSA), $1 for every $2 above it, capped at the supplement.

The supplement is one part of your retirement income. To compare claiming Social Security at 62 with waiting, try the Social Security break-even calculator. The retirement income tax calculator and the guide to pension and annuity withholding cover taxes on the annuity, and the FERS paycheck deductions guide explains what you pay into FERS while working.