The Federal Employees Retirement System — FERS — replaced the Civil Service Retirement System on January 1, 1987, and today covers virtually every civilian federal employee hired since 1984. FERS was designed to bring federal retirement benefits closer to private-sector norms by combining a smaller defined-benefit pension with Social Security coverage and the Thrift Savings Plan (TSP), the federal equivalent of a 401(k)). The three pieces together are meant to produce roughly the same lifetime income as the old CSRS, but with more portability and more individual control. Understanding how the pieces fit together — and how Congress has tweaked them for newer hires — is the foundation of any federal retirement plan.
The three-legged stool
FERS rests on three income sources: the FERS basic annuity (a defined-benefit pension funded by employee and agency contributions), Social Security (which CSRS employees did not pay into), and the Thrift Savings Plan. The basic annuity replaces a smaller share of pre-retirement income than CSRS did — typically 30% to 45% of high-3 pay for a career employee, compared with CSRS's 60% to 80%. Social Security then adds 20% to 30% for most career earners, and TSP supplements whatever gap remains, with a target of contributing 5% of pay to capture the full agency match.
The architecture matters because it shifts investment and longevity risk to the employee. A CSRS retiree with 40 years of service had a guaranteed, inflation-adjusted pension for life with no investment decisions to make. A FERS retiree must manage TSP allocation, decide when to claim Social Security, and may outlive TSP assets if withdrawals are too aggressive. The flip side is that FERS employees can take their TSP balance with them if they leave federal service before retirement age, while CSRS employees who left before retirement eligibility generally received nothing.
The annuity formula
The FERS basic annuity is computed as: High-3 average salary × Years of Creditable Service × Multiplier. The High-3 is the average of the highest 36 consecutive months of basic pay, typically the final three years but not necessarily — if you had a higher-paying assignment earlier in your career, that period can be the High-3.
The standard multiplier is 1.0%, meaning a 30-year career produces a pension equal to 30% of High-3 pay. Two important exceptions increase the multiplier. First, an employee who retires at age 62 or older with at least 20 years of service gets a 1.1% multiplier — a 10% bonus that materially raises the annuity. Second, certain "special category" employees — federal law enforcement officers, firefighters, air traffic controllers, Capitol Police, Supreme Court Police, Nuclear Materials Couriers, and members of the Diplomatic Security Service — receive a 1.2% multiplier for all years of service after 20, in recognition of the mandatory retirement age and physical demands of the work.
For a concrete example, an employee with a $120,000 High-3 and 30 years of service retiring at age 60 receives 30% × $120,000 = $36,000 per year, or $3,000 per month. The same employee waiting until age 62 receives 33% × $120,000 = $39,600, or $3,300 monthly — an 8% increase from the multiplier bump alone, before any additional salary or COLA accrual.
Minimum retirement age and eligibility rules
FERS defines a Minimum Retirement Age (MRA) that varies by birth year. Employees born before 1948 reached MRA at 55. The MRA then rises gradually: those born in 1953–1964 reach MRA at 56, those born in 1965–1969 reach it at 56 and 2 months to 56 and 10 months, and those born in 1970 or later reach MRA at 57. MRA is the earliest age at which an employee with 30 years of service can retire on an immediate, unreduced annuity.
FERS offers four immediate retirement pathways, each with its own age-and-service combination. MRA + 30 years is the most generous — full annuity, eligibility for the FERS annuity supplement, and immediate TSP access. Age 60 + 20 years also produces a full annuity and supplement eligibility. Age 62 + 5 years is the basic minimum combination for any employee, but it does not include the annuity supplement. Special category employees have their own rules: age 50 with 20 years of covered service, or any age with 25 years.
A fifth option, MRA + 10, lets employees retire at MRA with as few as 10 years of service, but the annuity is permanently reduced by 5% per year for each year the retiree is under age 62. A 57-year-old retiring under MRA + 10 faces a 25% reduction. The reduction can be avoided by postponing the annuity start date to age 62, which is a common strategy for employees who separate before 62 but want to preserve the full annuity amount.
FERS-RAE and FERS-FRAE: how newer employees differ
Congress has twice raised the employee contribution rate for FERS since the system was created. Employees first hired before January 1, 2013 contribute 0.8% of basic pay to the FERS annuity — the original 1987 rate. Employees first hired between January 1, 2013 and December 31, 2013 — known as FERS-RAE (Revised Annuity Employee) — contribute 3.1%, nearly four times as much. Employees first hired on or after January 1, 2014 — FERS-FRAE (Further Revised Annuity Employee) — contribute 4.4%.
The contribution difference is significant over a career. An employee earning $100,000 annually pays $800 per year under the original rate, $3,100 under FERS-RAE, and $4,400 under FERS-FRAE. Over a 30-year career, the FERS-FRAE employee pays roughly $108,000 more into the system than the original FERS employee — with no difference in the annuity formula or benefit amount. The higher contributions are a payroll tax in everything but name, used to reduce the federal deficit rather than fund additional benefits.
Rehired employees face complicated rules. A FERS employee who left federal service and returned after a break of more than 365 days generally becomes FERS-RAE or FERS-FRAE depending on the rehire date, even if they previously paid the 0.8% rate. The rules are detailed at 5 CFR § 841.502 and warrant careful review before accepting a federal job offer, because the lifetime cost of the higher contribution rate can run into six figures.
The annuity supplement bridge
The FERS annuity supplement — formally the Special Retirement Supplement — bridges the gap between FERS retirement and Social Security eligibility at age 62. It is paid only to retirees who meet certain eligibility thresholds (MRA + 30 years, age 60 + 20 years, or special category retirement) and is computed as a prorated Social Security benefit. The supplement is calculated as the Social Security benefit the retiree would receive at age 62, multiplied by the ratio of FERS years of service to 40.
A retiree with 30 years of FERS service and an estimated age-62 Social Security benefit of $2,000 per month would receive a supplement of $1,500 per month ($2,000 × 30/40) until age 62. The supplement is not inflation-adjusted and is subject to an annual earnings test — for 2025, the test reduces the supplement by $1 for every $2 of earned income above $23,400. The supplement ends permanently at age 62, regardless of whether the retiree actually claims Social Security.
The supplement is a substantial benefit for early retirees. A career federal employee retiring at 57 with the supplement can receive $15,000 to $25,000 per year of additional income for five years — money that, in many cases, makes early retirement financially viable. See our dedicated annuity supplement guide for the calculation details and pitfalls.
TSP contribution limits and matching
The Thrift Savings Plan is the defined-contribution leg of FERS, and contribution limits mirror 401(k) limits set by the IRS. For 2025, the elective deferral limit is $23,500. Employees age 50 and older can add a $7,500 catch-up contribution, bringing their total to $31,000. SECURE 2.0, enacted in December 2022, introduced a "super catch-up" of $11,250 for participants aged 60, 61, 62, and 63 — bringing the maximum to $34,750 for those in that narrow age band. This super catch-up is the largest of any defined-contribution plan in 2025.
FERS employees receive agency matching: 1% automatic contribution (whether or not the employee contributes), plus a dollar-for-dollar match on the next 3% of pay, plus a 50-cent match on the next 2% — for a total of 5% agency contribution when the employee contributes at least 5%. A FERS employee not contributing at least 5% is leaving free money on the table. The match vests immediately for the employee's own contributions and after three years for the agency automatic 1% — though the 3-year vesting was eliminated for new hires after October 1, 2020, so most current employees vest immediately.
Roth TSP, available since May 2012, lets employees make after-tax contributions that grow tax-free and can be withdrawn tax-free in retirement. The Roth option uses the same contribution limit as traditional TSP — they share a single $23,500 cap in 2025 — so employees must decide how to split their contributions. Higher-income employees often favor Roth TSP because federal salaries plus tax-deferred retirement income can push them into high brackets in retirement.
COLAs and survivor benefits
FERS annuities are not inflation-adjusted until the retiree reaches age 62 — and even then, the FERS COLA is a "diet COLA" that can lag the Consumer Price Index. When CPI-W is 2% or less, FERS retirees receive the full COLA. When CPI-W is between 2% and 3%, FERS retirees receive 2%. When CPI-W is 3% or more, FERS retirees receive CPI-W minus 1%. By contrast, CSRS retirees receive the full CPI-W COLA from the moment they retire.
This diet-COLA structure compounds over a long retirement. A FERS retiree who lives 25 years post-retirement during a period of 3% average inflation would see their annuity lose roughly 15% to 20% more purchasing power than a CSRS retiree with the same starting benefit. For employees retiring before 62, the gap is even larger because no COLA is paid until 62 — meaning the annuity is eroded by inflation for years before any adjustment occurs.
Survivor benefits are available under FERS but require an election and a corresponding annuity reduction. A retiring employee can elect a full survivor benefit for a spouse (the annuity is reduced by 10%) or a partial survivor benefit of any amount up to 50% of the annuity (the reduction is 5% for a 25% survivor benefit, with proportional reductions in between). The survivor election also affects the surviving spouse's continued FEHB coverage and eligibility for the FERS survivor annuity. For help running the annuity calculation on your own salary and years, try our FERS pension calculator, and for a deeper look at the comparison with the legacy system, see our FERS vs CSRS guide.
Last reviewed July 10, 2026. This article is informational and does not constitute legal, tax, or financial advice. Consult a qualified professional for guidance specific to your situation.