How is a CSRS annuity calculated?

Three rates stack under 5 U.S.C. 8339(a). You get 1.5 percent of your high-3 average pay for each of your first 5 years of service, 1.75 percent for years 5 through 10, and 2 percent for every year past 10. At 30 years that works out to 56.25 percent of high-3. At 41 years and 11 months the formula reaches 80 percent, which is the statutory ceiling.

Can a CSRS annuity go above 80 percent of high-3?

Yes, but only through unused sick leave. 8339(f) caps the annuity from your service at 80 percent of average pay; 8339(m) credits sick leave "without regard to the limitations imposed by subsection (f)." OPM’s Handbook ch. 50 example has 43 years of service plus 2,087 sick leave hours drawing 82 percent of high-3. Sick leave never counts toward eligibility or high-3.

When can I retire under CSRS?

Three combinations give an immediate unreduced annuity under 5 U.S.C. 8336: age 55 with 30 years, age 60 with 20 years, or age 62 with 5 years. An early out or an involuntary separation under 8336(d) opens at 25 years at any age, or age 50 with 20 years, but 8339(h) then cuts the annuity by one sixth of 1 percent for each full month you are under 55. That is 2 percent a year.

What does the survivor election cost me?

Under 5 U.S.C. 8339(j)(4) your annuity drops by 2.5 percent of the first $3,600 of the survivor base plus 10 percent above $3,600. The survivor then gets 55 percent of that base under 8341(b)(1). On a $50,000 annuity with a full election that is $4,730 a year, for a $27,500 survivor annuity. A smaller base needs written spousal consent.

How does unused sick leave convert to service credit?

OPM uses the 2,087-hour chart in Handbook chapter 50: 174 hours is one month and 2,087 hours is a year. Hours between two chart entries round up. So 1,243 hours reads as 7 months 5 days, and 2,000 hours as 11 months 15 days. The credit joins your service total, then leftover days are dropped.

How does the CSRS Offset reduction work at 62?

At Social Security eligibility, normally 62, your CSRS annuity drops. Under 5 U.S.C. 8349(a)(3) the cut is the smaller of two figures: the part of your Social Security benefit SSA attributes to federal earnings, or your offset service years divided by 40 times that benefit. OPM’s example is 6 offset years and a $500 monthly benefit, so 6/40 times $500, or $75 a month. Total income does not fall, because Social Security starts at the same time.

Why can this tool only estimate the CSRS Offset?

The first of the two statutory figures needs SSA to run two full benefit computations from your complete lifetime earnings record, one with your federal wages and one without. No calculator has that record. This tool computes the second figure, which the statute makes the ceiling, so your real offset can be smaller than the number shown but never larger.

What counts as high-3 average pay under CSRS?

5 U.S.C. 8331(4) defines average pay as the largest annual rate from averaging your basic pay over any 3 consecutive years of creditable service, each rate weighted by how long it was in effect. The three years need not be your last three, or line up with calendar years.

Calculator

CSRS Retirement Calculator

Estimate your Civil Service Retirement System annuity: the three rate tiers, the 80 percent limit, the sick leave credit that beats that limit, what the survivor election costs you, and the CSRS Offset reduction at 62.

Reviewed by Jonathan D., 20-year federal employee · Formulas verified against OPM CSRS Handbook ch. 50 · Updated October 2026

Reviewed October 3, 2026 · Sources: 5 U.S.C. 8339 (computation), 5 U.S.C. 8336 (eligibility), OPM Handbook ch. 50, 5 U.S.C. 8349 (CSRS Offset) · Inputs stay in your browser. Nothing you type is sent anywhere.

High-3 average pay

The highest average of your basic pay over any 3 straight years of service, weighted by how long each rate was in effect.

Creditable service

Years

Months

Days

Civilian service plus any military service you paid a deposit for. Take the total from your service history, not from your hire date.

Unused sick leave hours

From your leave and earnings statement. Under 5 U.S.C. 8339(m) this credit is added without regard to the 80 percent limit, so it can push your annuity above 80 percent of high-3.

Age at retirement

Years

Months

Type of retirement

An early out under 5 U.S.C. 8336(d) needs 25 years at any age, or age 50 with 20 years, and costs 2 percent a year for every year you are under 55.

Which CSRS are you in

Survivor benefit election

Electing less than the maximum needs your spouse's written consent.

You meet CSRS retirement at age 55 with 30 years, and your estimated annuity is $47,891 a year, or $3,990 a month, after the elections you chose.

Annuity before elections

$52,913

62.25 percent of high-3

What you receive

$47,891

$3,990 a month

Survivor would receive

$29,102

55 percent of the elected base

Unused sick leave credit (OPM 2087-hour chart)6 months, 0 days

Total service used in the formula, days dropped33 years, 0 months

First 5 years at 1.5% on 5.0000 years$6,375.00

Years 5 to 10 at 1.75% on 5.0000 years$7,437.50

Years over 10 at 2% on 23.0000 years$39,100.00

80 percent limit on high-3 (sick leave excluded from the test)$68,000.00

Sick leave add-on, which the limit does not cap+ $850.00

Annuity before reductions$52,912.50

Survivor election, 2.5 percent of the first $3,600 plus 10 percent above it- $5,021.25

Annual annuity payable$47,891.25

Monthly rate, divided by 12 and rounded down to the dollar$3,990

Rates come from 5 U.S.C. 8339(a): 1.5 percent of high-3 for the first 5 years, 1.75 percent for years 5 through 10, and 2 percent for service past 10 years. The limit at 80 percent is 8339(f). OPM publishes the factor to six decimal places, and this tool rounds the same way so the dollars match the agency worksheet.

What this models

What the CSRS Retirement Calculator models and what it does not model
Modeled	Not modeled
The three rate tiers in 5 U.S.C. 8339(a), with OPM’s six-decimal factor rounding	The law enforcement and firefighter formula in 8339(d), which pays 2.5 percent on the first 20 years
The 80 percent limit in 8339(f), tested on civilian and military service only	Service credit disputes. We use the service total you type, not your official record
Unused sick leave credit under 8339(m), added above the limit	Leave without pay over 6 months in a calendar year, which reduces creditable service
The survivor election cost in 8339(j)(4) and the 55 percent payout in 8341(b)(1)	A custom survivor base. CSRS lets you name any amount up to the full annuity; "partial" here means half. Also outside scope: former spouse court orders, insurable interest elections and the deposit for a post-retirement marriage
The age reduction in 8339(h) for an early out under 55	The reduction for unpaid pre-October 1982 civilian deposit service
The CSRS Offset ceiling in 8349(a)(3)(B), which is years of offset service over 40	The other offset limb in 8349(a)(3)(A), which needs your full SSA earnings record. The real offset can be smaller than shown, never larger
Annual and monthly figures, with the monthly rate rounded down to the dollar	Tax, FEHB and FEGLI withholding, and COLAs after retirement under 8340

Precision limit: OPM publishes its annuity factor to six decimal places, and this tool rounds the same way, so dollar figures match the agency worksheet to the cent. Service is counted in whole months with 30-day months, matching OPM practice. Only your HR benefits officer can certify your service record.

Where the 80 percent ceiling actually bites

Most CSRS employees never reach the limit. The formula hits 80 percent of high-3 at 41 years and 11 months of service, so a career that started at 22 crosses it around age 64. Anyone who gets there has been working long enough that each additional year buys nothing except a larger sick leave balance.

That is the quiet part of the rule. Sick leave sits outside the ceiling. OPM's own example in Handbook chapter 50 walks through an employee with 43 years of service and a full year of unused sick leave, and the annuity lands at 82 percent of high-3. If you are past the limit, every 174 hours of sick leave you keep is worth a further 2 percent of a year of service, and every hour you burn is gone.

Why CSRS Offset looks like a pay cut and is not

CSRS Offset covers people who came back to federal service after 1983 with earlier CSRS time. They pay into both CSRS and Social Security on the same wages. At 62 the CSRS side steps down, and the usual reaction is that the government is clawing something back.

The arithmetic says otherwise. Social Security starts the same month the offset starts, and the offset is capped at your offset service over 40 of the Social Security benefit. Six offset years cap the cut at 15 percent of that check. Total income goes up. What changes is which agency sends the money.

The survivor election is cheaper than people assume

A full election costs about 10 percent of your annuity and pays your spouse 55 percent of it for life, with the same cost-of-living increases. Only 2.5 percent is charged on the first $3,600 of the base, so the effective cost on a modest annuity runs under 10 percent. Declining it needs your spouse's written consent, and the choice is close to irreversible once payments start.