Calculate your exact monthly annuity under FERS, CSRS, or FERS Special (LEO/Firefighter). Includes High-3 salary, SBP options, and FERS Supplement estimate.
Select your plan type; inputs and multiplier rules update automatically.
| Plan | Multiplier | High-3 Base | SS Covered | COLA |
|---|---|---|---|---|
| FERS | 1.0% (1.1% at 62+/20+) | Yes | Yes | CPI − 1 pt (or less) |
| FERS Special (LEO/FF) | 1.7% (first 20 yrs) + 1.0% | Yes | Yes | Same as FERS |
| CSRS | Tiered (1.5/1.75/2.0%) | Yes | No | Full CPI |
| CSRS Offset | Same as CSRS, offset by SS | Yes | Yes | Full CPI |
CSRS tiered rate: 1.5% × first 5 years + 1.75% × next 5 years + 2.0% × remaining years. Source: OPM.
The FERS Supplement bridges the gap between FERS retirement and Social Security eligibility (age 62). It approximates the SS benefit earned during federal service. It stops at 62 regardless of whether you claim Social Security, and it's subject to an earnings test — earning more than ~$22,000/year from post-retirement work reduces it dollar-for-dollar above the threshold.
The supplement is calculated as: (SS benefit earned during federal service) × (federal years ÷ 40). For most employees with 25–30 years, this is $700–$1,100/month.
FERS monthly annuity = (Years of Service × 1.0% × High-3 Average Salary) ÷ 12. The multiplier increases to 1.1% if you retire at age 62 or older with at least 20 years of service — a 10% bonus for staying to 62.
High-3 is the average of your three consecutive highest-earning years of federal service. It doesn't have to be your last three years — if you had a higher-earning period earlier in your career, those years can count.
The FERS Supplement stops at age 62. It cannot be extended. It's also reduced by $1 for every $2 of outside earned income above the annual exempt amount (~$22,320 for 2026). Investment income and pensions don't count against this limit.
CSRS has a higher multiplier and full CPI COLA — for long-career employees (30+ years), CSRS produces significantly higher benefits than FERS. However, CSRS employees don't receive Social Security or the government's TSP match. FERS employees benefit from Social Security + TSP match + the FERS Supplement, making the total compensation package competitive.