CSRS Annuity Calculator

How this is calculated

CSRS closed to new hires on 1 January 1987. Anyone still covered by it was hired before then, which means almost every CSRS employee still serving is near or past the point where the formula stops rewarding another year — so the ceiling, the sick leave exception and the survivor election matter more here than the basic arithmetic does.

The tiered formula

1.5%× high-3 × first 5 years
+ 1.75%× high-3 × next 5 years
+ 2%× high-3 × all service beyond 10 years

5 U.S.C. § 8339(a) sets all three rates. The consequence people miss is that the average year of a CSRS career is worth less than the marginal one: thirty years comes to 56.25% of high-3, an average of 1.875% a year, while the thirty-first year is worth a full 2%. Service is counted in whole years and months on OPM’s 360-day service year, and the odd days that do not complete a month are dropped.

The 80% ceiling, and the one thing that beats it

§ 8339(f) caps the annuity earned by actual service at 80% of high-3. Running the tiers forward, that arrives at 41 years and 11 months of service — 41 years and 10 months yields 79.92%, and one more month crosses the line. Past that point further service adds nothing to the annuity, although the retirement contributions withheld from your pay for the excess service are refunded to you with interest when you retire, and further years still raise your high-3 if your pay is rising.

The same subsection exempts credit for unused sick leave from the ceiling. That exemption is why this calculator cannot simply add sick leave to service and run the formula once: it computes the annuity from your actual service, caps that, and then adds what the sick leave earns on top. When the cap does not bind, the two are identical. When it does, the difference is the entire sick leave credit — and a CSRS annuity above 80% of high-3 is always sick leave and nothing else.

The conversion itself is OPM’s 2,087-hour chart, the same lookup the sick leave calculatorperforms — not a division. Sick leave never counts toward eligibility to retire, only toward the computation.

When you can go, and what leaving early costs

5 U.S.C. § 8336 pays an immediate, unreduced annuity at age 55 with 30 years of service, age 60 with 20, or age 62 with 5. There is no CSRS equivalent of the FERS MRA+10 retirement: below those combinations, the only immediate annuity is an early-out.

An early-out — a Voluntary Early Retirement Authority offer, or a discontinued service retirement after an involuntary separation — is payable at age 50 with 20 years, or at any age with 25. § 8339(h) then reduces it at two different rates: one sixth of one percent for each month you are under 55 for the first five years, which is 2% a year, and one twelfth of one percent a month beyond that, which is 1% a year. The reduction is permanent. It does not lift when you reach 55, and it does not lift at 62.

Two eligibility rules this tool does not check, because it does not ask for the history they turn on: you need 5 years of creditable civilian service, and you must have been covered by CSRS for at least 1 of the last 2 years before you separate.

The survivor election is priced in dollars, not percent

FERS charges a flat percentage. CSRS does not. § 8339(j) reduces your annuity by 2.5% of the first $3,600 of the base you elect plus 10% of everything above it, and § 8341(b) pays your survivor 55% of that base for life. The $3,600 break point is statutory and has never been indexed, so on any modern salary the cheap first tier is worth about $270 a year and the cost is effectively a flat 10%.

You may base the election on any amount up to the full annuity. Both the cost and the survivor’s benefit scale with the base, so a partial election is a genuine dial rather than a lesser version of the full one. The survivor benefit is computed on the base before the reduction that pays for it, and it is never reduced by the CSRS Offset.

CSRS Offset

CSRS Offset covers employees who left federal service, came back after 1983 with five or more years of prior CSRS service, and are now paying into both CSRS and Social Security. The annuity is computed under ordinary CSRS rules and paid in full until age 62. At 62— or at retirement, for someone already past it — 5 U.S.C. § 8349 reduces OPM’s payment by the Social Security your Offset service bought.

The statute takes the lesser of two figures: the difference between your Social Security benefit computed with and without the Offset service, or your benefit times years of Offset service over 40. The first requires your full earnings record and cannot be reconstructed here, so this tool computes the second — which is the estimate OPM itself publishes. Because the real offset is the lesser of the two, the figure shown is an upper bound on the reduction, and the post-62 annuity is therefore a floor rather than a forecast.

The reduction is not a loss of benefits. Social Security begins paying roughly what OPM stops paying, so total income barely moves — but the deposit from OPM shrinks, and nobody warns you the month before.

WEP and GPO no longer apply

The Windfall Elimination Provision and the Government Pension Offset, which for decades reduced the Social Security payable to CSRS retirees and their spouses, were repealed by the Social Security Fairness Act (Pub. L. 118-273), signed 5 January 2025 and effective for benefits payable after December 2023. A great deal of CSRS guidance still online predates that repeal. If you are reading advice that cuts your Social Security because you have a CSRS pension, check its date.

CSRS Offset is a separate mechanism and was not repealed. It reduces the CSRS annuity, not the Social Security benefit, and it continues to apply.

What this does not model

• Deposits and redeposits.Unpaid non-deduction service, and refunded service you have not repaid, change both the credited service and the annuity in ways that depend on when the service was performed. Neither is reconstructed here — enter the service you know is fully creditable.
• Part-time proration. Part-time service after 6 April 1986 is prorated by the hours actually worked. This tool takes service as you enter it.
• Military service. Post-1956 military service needs a deposit to count, and a Catch-62 reduction applies if it is unpaid and you become eligible for Social Security at 62.
• Disability and special provisions. CSRS disability retirement has a guaranteed minimum computation of its own, and law enforcement, firefighter and air traffic controller service is computed at higher rates. Neither is modelled.
• COLAs, tax, insurance and court orders. The figure shown is a starting gross annuity. CSRS annuities receive a full cost-of-living adjustment each year; FEHB and FEGLI premiums, federal and state tax, and any court-ordered apportionment all come out before you see the money.
• The alternative form of annuity and the voluntary contributions program, both of which change the payment in exchange for a lump sum.

Sources

• OPM CSRS/FERS Handbook, Chapter 50 — Computation of Annuity Under the General Formula (PDF) — the tiered formula, the 80% maximum, the sick leave exception, and the order the reductions are applied in.
• 5 U.S.C. § 8339 — the rates (a), the maximum (f), the early-retirement reduction (h), and the survivor election (j).
• 5 U.S.C. § 8336 — immediate retirement eligibility, including the early-out combinations.
• 5 U.S.C. § 8349 — the CSRS Offset reduction and the two figures it takes the lesser of.
• OPM — CSRS Computation — OPM’s own summary of the general formula and the reductions.
• SSA — Social Security Fairness Act — the repeal of WEP and GPO, effective for benefits payable after December 2023.

Last reviewed: August 2026