Last Updated: October 14, 2026 Reading Time: 9 min

FedWeek's September 30 column asked whether to work longer or take the FERS supplement now and ended at "it depends." It gave one example, a $1,000-a-month supplement, and no break-even math. This post supplies the numbers. If you are MRA-eligible with 30 years and typing "fers supplement calculator" into Google, here is what one, two or three more years actually buy you, measured two ways: retirement income alone, and retirement income plus the paycheck you keep earning.

How the Supplement Is Computed

The FERS annuity supplement is set by 5 U.S.C. § 8421 and 5 C.F.R. § 842.504. OPM takes the Social Security old-age benefit you would get at 62, computed as if you were already 62 with no wages after your separation, and multiplies it by your FERS civilian service divided by 40.

Three rules shape the fraction. OPM rounds your service to the nearest whole year, with a half year rounding up, so 30 years and 6 months counts as 31 and 30 years and 5 months counts as 30. The numerator is capped at 40. Ordinary bought-back military service is excluded from the supplement fraction under 5 C.F.R. § 842.504(a)(1); military service performed during qualifying leave without pay from civilian service is treated differently.

A rough planning estimate for 30 qualifying years is 75% of an age-62 Social Security estimate; OPM's actual computation can differ. On an $1,800 estimate that is $1,350 a month. On $2,200 it is $1,650.

Who gets it matters as much as how much. The supplement comes with an immediate annuity at MRA+30, at 60+20, or under the law enforcement, firefighter and air traffic controller provisions. A VERA retiree gets it starting at their MRA, not at separation. MRA+10 retirements, deferred retirements and disability retirements do not carry it; § 8421 never names them. And an annuity that starts at 62 or later gets no supplement at all. The full rules are in our FERS special retirement supplement guide.

What One More Year Adds to the Annuity

Each additional year of service before 62 adds exactly 1% of your high-3 to the annuity under 5 U.S.C. § 8415(a). The 1.1% rate in § 8415(i) requires both age 62 and 20 years of service, so it is never reached in a retire-at-57-versus-60 decision.

Unused sick leave counts in the annuity at 100% for separations after December 31, 2013. Every 174 hours is roughly a month of service under OPM's 2,087-hour year. The model assumes no sick leave. Adding sick-leave credit can change the comparison.

While you keep working, your agency keeps paying 1% of basic pay into your TSP automatically plus a match of up to 4% when you contribute 5%, under 5 U.S.C. § 8432(c). That is $4,500 a year on a $90,000 salary, $5,500 on $110,000 and $6,500 on $130,000, and it ends at separation.

The Break-Even Table

Inputs: retire at exactly 57 with exactly 30 years of FERS civilian service (MRA 57, born 1970 or later). The work-longer cases retire at 58, 59 or 60 with 31, 32 or 33 years. High-3 is held flat in the extra years as a simplifying base case. The Social Security estimate at 62 is held flat. Annuity equals high-3 times years times 1%. Supplement per year equals 12 times the Social Security estimate times years divided by 40. As a simplifying assumption, the supplement is paid for five, four, three or two years through the month of the 62nd birthday; under 5 U.S.C. § 8421(a)(3)(B) it can end earlier, and the birthday month is not always payable. Everything is in nominal dollars: no COLA on either side, no investment return, no taxes, no survivor reduction, no sick leave, and the earnings test is not triggered because the retiree does not work. Dollars are exact, not rounded.

"Retirement income to 80" is cumulative annuity plus supplement from 57 to 80. "Shortfall" is how much less retirement income the work-longer case has collected by 80 than retiring at 57. "Gross cash gap" adds the extra years of gross salary back in. "Crossover" is the age at which the work-longer case's cumulative retirement income finally catches up, on benefits alone.

High-3 SS at 62 Option Annuity per year Supplement per year Retirement income to 80 Shortfall at 80 Gross cash gap at 80 Crossover age
$90,000 $1,800 Retire at 57 $27,000 $16,200 $702,000 n/a n/a n/a
$90,000 $1,800 Work 1 more year $27,900 $16,740 $680,760 $21,240 $68,760 103.6
$90,000 $1,800 Work 2 more years $28,800 $17,280 $656,640 $45,360 $134,640 105.2
$90,000 $1,800 Work 3 more years $29,700 $17,820 $629,640 $72,360 $197,640 106.8
$90,000 $2,200 Retire at 57 $27,000 $19,800 $720,000 n/a n/a n/a
$90,000 $2,200 Work 1 more year $27,900 $20,460 $695,640 $24,360 $65,640 107.1
$90,000 $2,200 Work 2 more years $28,800 $21,120 $668,160 $51,840 $128,160 108.8
$90,000 $2,200 Work 3 more years $29,700 $21,780 $637,560 $82,440 $187,560 110.5
$110,000 $1,800 Retire at 57 $33,000 $16,200 $840,000 n/a n/a n/a
$110,000 $1,800 Work 1 more year $34,100 $16,740 $817,160 $22,840 $87,160 100.8
$110,000 $1,800 Work 2 more years $35,200 $17,280 $791,040 $48,960 $171,040 102.3
$110,000 $1,800 Work 3 more years $36,300 $17,820 $761,640 $78,360 $251,640 103.7
$110,000 $2,200 Retire at 57 $33,000 $19,800 $858,000 n/a n/a n/a
$110,000 $2,200 Work 1 more year $34,100 $20,460 $832,040 $25,960 $84,040 103.6
$110,000 $2,200 Work 2 more years $35,200 $21,120 $802,560 $55,440 $164,560 105.2
$110,000 $2,200 Work 3 more years $36,300 $21,780 $769,560 $88,440 $241,560 106.8
$130,000 $1,800 Retire at 57 $39,000 $16,200 $978,000 n/a n/a n/a
$130,000 $1,800 Work 1 more year $40,300 $16,740 $953,560 $24,440 $105,560 98.8
$130,000 $1,800 Work 2 more years $41,600 $17,280 $925,440 $52,560 $207,440 100.2
$130,000 $1,800 Work 3 more years $42,900 $17,820 $893,640 $84,360 $305,640 101.6
$130,000 $2,200 Retire at 57 $39,000 $19,800 $996,000 n/a n/a n/a
$130,000 $2,200 Work 1 more year $40,300 $20,460 $968,440 $27,560 $102,440 101.2
$130,000 $2,200 Work 2 more years $41,600 $21,120 $936,960 $59,040 $200,960 102.7
$130,000 $2,200 Work 3 more years $42,900 $21,780 $901,560 $94,440 $295,560 104.2

Computed by FedTools from 5 U.S.C. § 8415(a) and 5 C.F.R. § 842.504(a). Retirement income is annuity plus supplement, nominal, pre-tax. The gross cash gap is gross salary for the extra years minus the shortfall; it does not subtract the FERS employee contribution or income tax on that salary, and it does not add the agency TSP contribution.

Spot-check on the largest cell: at $130,000 and $2,200, retiring at 57 collects $39,000 times 23 years plus five years of $19,800 by age 80: $897,000 plus $99,000 equals $996,000. Working three more years collects $42,900 times 20 years plus two years of $21,780: $858,000 plus $43,560 equals $901,560. The shortfall is $94,440, and the gross cash gap is $390,000 minus $94,440, or $295,560.

Reading the Table Honestly

The shortfall column is the whole pension-side story. Working one more year costs $21,000 to $28,000 of retirement income by age 80, because you give up a full year of annuity plus most of a year of supplement to buy a 1% bump that then has fewer years to pay out. On benefits alone, the crossover never arrives in a normal lifetime. That is arithmetic.

The gross cash gap column is why people stay anyway. A year of salary is roughly four to five times the retirement income, measured to age 80, that the year costs you. For spendable cash, subtract taxes, retirement deductions and your own TSP deferrals from that pay. For total compensation, include salary plus the agency's 5% TSP contribution without adding your own deferrals again. Either way the extra year is far ahead on cash. The honest framing is that the pension math says retire and the paycheck says stay, and the table tells you the exact size of each.

Two things move the answer at the margin. A rising high-3 helps the work-longer case: a 2% raise in the extra year lifts the three-year average by about 0.7% (one year of three), and the annuity rises by that same 0.7% on top of the extra year's 1%, and a full-grade promotion in the final years changes the shape of the comparison. And the flat-dollar assumption cuts both ways, because the annuity gets no COLA before 62 for regular FERS retirees under 5 U.S.C. § 8462(c)(3), so a 57-year-old retiree's annuity is flat for five years. Law enforcement, firefighter and air traffic controller retirees are the exception.

What the Table Leaves Out

The earnings test

The table assumes you do not work after retiring. If you do, the supplement is reduced by 50% of your earnings above the Social Security exempt amount, which is $24,480 for 2026 under the Federal Register notice at 90 FR 49050. The reduction is applied during the 12 months that begin the July after the year you earned the money, so 2026 earnings over the limit reduce your supplement from July 2027 through June 2028. OPM spreads it across the year, never takes more than a month's supplement in a month, and can suspend the supplement if you do not return its earnings survey. SSA sets the 2027 exempt amount with the October cost-of-living announcement; check ssa.gov/cola for the figure. Details and worked examples are in the FERS supplement earnings limit guide.

Taxes

The comparison above is pre-tax on both sides. See the FERS special retirement supplement guide for more on the supplement.

The age-62 cliff

The supplement ends at the earlier statutory boundary, regardless of whether you file for Social Security, and the birthday month is not always payable; the table uses a simplified five-year bridge. What replaces it is the subject of our supplement 62 cliff and Social Security timing post.

MRA+10

If you do not have 30 years at 57, the decision is different. An MRA+10 annuity carries no supplement and is reduced by five-twelfths of 1% for each full month you are under 62 when it starts, unless you postpone the start until the date you would have met 60+20 or MRA+30. See the MRA+10 retirement guide.

The elimination rumor

We keep the status of the elimination rumors current in FERS supplement eliminated: rumors vs confirmed.

The TSP side

Retiring at 57 means a longer drawdown and more sequence risk. That is covered in MRA+30 early retirement and TSP sequence risk, and the companion piece on why feds work longer than they need to carries GAO's data on over-working.

Run Your Own Numbers

Use our free FERS Supplement Calculator to see your monthly and annual supplement: enter your estimated annual Social Security benefit at 62 (multiply a monthly estimate by 12), your FERS years, your current age and your birth year, and it returns the monthly supplement, the annual supplement and your FERS service ratio. Estimate your supplement

Then use the FERS Retirement Calculator to estimate your annuity and supplement together and compare retirement dates, and the High-3 Calculator to find your highest 36-month average if a promotion or locality change sits inside your final three years.

Frequently Asked Questions

How much is the FERS supplement if I retire at 57 with 30 years?

A rough planning estimate is your estimated age-62 Social Security benefit times 30 divided by 40, which is 75% of it: about $1,350 a month on an $1,800 estimate and $1,650 on a $2,200 estimate. OPM's actual computation can differ.

Does working one more year break even against taking the supplement now?

On pension plus supplement alone, no. In every work-longer case in our table (six input pairs, three later retirement ages each) the later retirement does not catch up before age 98. The extra year pays through salary and the agency's TSP contributions (5% of pay if you contribute 5%), not through the 1% annuity increase.

If I wait until 60, do I get the 1.1% multiplier?

No. The 1.1% rate in 5 U.S.C. § 8415(i) requires both age 62 and 20 years of service, so a regular FERS employee retiring at 58, 59 or 60 earns 1% per year of service.

Can I work part-time after retiring and keep the full supplement?

Up to the Social Security exempt amount, which is $24,480 in 2026. Above it, OPM reduces the supplement by half the excess, applied from July of the following year through the next June.

Does my unused sick leave raise the supplement?

It raises the annuity, where it counts at 100% for separations after December 31, 2013.

Does my FERS annuity get a COLA if I retire at 57?

Not until 62. Under 5 U.S.C. § 8462(c)(3), cost-of-living adjustments are not effective for regular FERS retirees under 62. Law enforcement, firefighter and air traffic controller retirees are the exception.

Does bought-back military time count toward the supplement?

Ordinary bought-back military service is excluded from the supplement fraction under 5 C.F.R. § 842.504(a)(1); military service performed during qualifying leave without pay from civilian service is treated differently.

Sources: 5 U.S.C. § 8421; 5 U.S.C. § 8421a; 5 C.F.R. § 842.504; 5 C.F.R. § 842.505; 5 U.S.C. § 8412; 5 U.S.C. § 8415; 5 U.S.C. § 8432; 5 U.S.C. § 8462; SSA, Cost-of-Living Increase and Other Determinations for 2026, 90 FR 49047; FedWeek, Work Longer or Take the FERS Supplement Now: Which Is Better? (Sept. 30, 2026).