CSRS vs FERS: What's the Real Difference?

CSRS was closed to new employees after December 31, 1983. Anyone hired (or rehired without a break in service) after that date is under FERS. If you started federal service before 1984 and have been continuously covered, you are likely still CSRS or CSRS Offset.

CSRS Offset is a hybrid: you are covered by CSRS but also paid Social Security taxes on earnings from 1984 onward. When you retire, your CSRS annuity is offset (reduced) by the Social Security benefit you earned from federal service. Many feds in this category do not realize they are offset until they see their first Social Security statement.

As of April 2026, roughly 50,000 CSRS employees remain in the workforce, concentrated in longer-tenured positions at agencies like State, VA, and DoD. If you are one of them, your retirement planning is materially different from FERS.

CSRS uses a tiered formula: 1.5% per year for the first 5 years, 1.75% per year for years 6-10, and 2.0% per year for every year after 10. The maximum benefit is 80% of your high-3, reached at around 41.5 years of service.

A CSRS employee with 35 years of service and a high-3 of $95,000 receives: (5 x 1.5%) + (5 x 1.75%) + (25 x 2.0%) = 7.5% + 8.75% + 50% = 66.25% of $95,000 = $62,937 per year, or $5,245 per month.

The equivalent FERS calculation for 35 years at the standard 1.0% rate: 35 x 1.0% x $95,000 = $33,250 per year. If you qualify for the 1.1% rate (age 62+ with 20+ years), it would be $36,575. CSRS pays nearly double the pension for the same career length.

CSRS annuities receive full COLA every year, tied to CPI. FERS annuities are capped at CPI-1% when inflation is above 3%, and capped at 2% when CPI is between 2% and 3%. Over a 25-year retirement with average 3% inflation, CSRS retirees come out meaningfully ahead on COLA alone.

FERS was designed with the "three-legged stool" in mind: pension + Social Security + TSP. CSRS employees do not pay Social Security taxes on federal earnings and generally do not qualify for Social Security from their federal career. If they have enough outside employment to qualify, they may receive Social Security from those non-federal earnings. Before January 2025, the Windfall Elimination Provision (WEP) reduced those benefits by up to $587/month, and the Government Pension Offset (GPO) could reduce spousal benefits. The Social Security Fairness Act, signed January 5, 2025 (Public Law 118-273), repealed both WEP and GPO for all benefits payable after December 2023. CSRS retirees' Social Security from outside employment is no longer reduced by WEP.

TSP matching is the biggest FERS advantage in accumulation. Under FERS, OPM automatically contributes 1% of your salary to TSP even if you contribute nothing. If you contribute at least 5%, you get a total of 5% from the government (1% automatic + 4% match). On a $90,000 salary, that is $4,500 per year in free money. CSRS employees receive no matching contributions.

The FERS Supplement bridges the gap between early retirement and Social Security eligibility. A FERS employee who retires at 57 with 30 years can receive $1,200/month from the Supplement until age 62 , that is $72,000 in additional income the CSRS employee does not receive (because they are not covered by Social Security).

CSRS employees contribute 7% of base pay toward their annuity. CSRS Offset employees pay 0.8% (the rest flows to Social Security). FERS employees hired before 2013 pay 0.8%; those hired in 2013 pay 3.1%; those hired in 2014 and later pay 4.4%. The contribution rate does not affect your annuity amount.

A CSRS employee earning $90,000 contributes $6,300 per year to the retirement fund. A newer FERS employee at the same salary contributes $3,960 (4.4%). The FERS employee keeps $2,340 more per year to invest in TSP , and gets matching on top of it. The net cash position during the career is better under FERS for employees who use the TSP.

For high-career, long-tenure employees, CSRS usually wins on total lifetime income from the pension alone , especially when COLA compounding is factored in. A CSRS retiree with 40 years of service and a $100,000 high-3 retires with roughly $80,000 per year growing with full CPI. A FERS employee with the same high-3 and career gets about $44,000 in pension but adds Social Security ($18,000-$28,000 per year) and whatever TSP accumulation they have built.

When Social Security and TSP are included, FERS employees with disciplined TSP saving often match or exceed CSRS total income. The key variable is TSP balance: a FERS employee who contributed 15% for 30 years and captured all matching has a TSP balance of $600,000-$900,000 at retirement, generating $24,000-$36,000 per year in sustainable withdrawals. That stacks on top of the FERS pension.

Our team at PlanWell runs this analysis side by side for clients who want the full picture. The answer depends on your salary history, expected Social Security benefit, TSP balance, and life expectancy.

This content is educational and general in nature. It is not tax, legal, or investment advice for your specific situation. Rules for FERS, TSP, Social Security, Medicare, and tax treatment change and can depend on factors unique to you. Consult a qualified tax professional, attorney, or CFP professional before acting on any of the strategies discussed here. PlanWell Financial Planning, LLC is not affiliated with or endorsed by OPM, the U.S. Office of Personnel Management, or any federal agency.