FERS vs CSRS Retirement Calculator

Who still has CSRS

The Civil Service Retirement System closed to new federal employees on January 1, 1987. Every federal worker hired after that date entered FERS. In 2026, the youngest possible CSRS employee hired in the final days of December 1986 is approaching 60 years old. Most active CSRS employees are in their mid-to-late 60s. The population is tiny and shrinking every year through retirements and deaths.

OPM's most recent data shows more CSRS retirees drawing benefits than active CSRS employees still working. Within a decade, active CSRS participation in the federal workforce will be functionally zero. The comparison matters now primarily because CSRS retirees, their surviving spouses, and employees approaching the end of long careers are still making real financial decisions based on which system they're in.

The CSRS formula produces much larger pensions

CSRS uses a stepped accrual rate. The first 5 years of service accrue at 1.5% per year. Years 6 through 10 accrue at 1.75%. Year 11 onward accrues at 2.0%. The benefit is capped at 80% of the high-3 average salary, which requires roughly 41 years and 11 months of service.

A 30-year CSRS employee earns: (5 x 1.5%) + (5 x 1.75%) + (20 x 2.0%) = 7.5% + 8.75% + 40% = 56.25% of high-3 salary. On a $90,000 high-3, that's $50,625 per year, $4,219 per month.

Under FERS, that same 30-year employee at age 62 with 20+ years gets the 1.1% multiplier: 30 x 1.1% = 33% of high-3 = $29,700 per year. Before age 62 or without 20 years, it's 30 x 1.0% = $27,000. The CSRS pension is 70-87% larger on identical inputs.

This gap is by design. CSRS was structured to be the primary retirement vehicle. FERS was structured around three legs: a smaller pension, Social Security, and the TSP with a 5% employer match. CSRS members get none of those extras. The pension has to carry more weight, so the formula was built to produce more.

The FERS advantages that partially close the gap

The Social Security offset is real. A FERS employee retiring at 62 might receive $1,200-$1,800 per month in Social Security earned during their federal career. Over 20 years, that's $288,000 to $432,000 in additional income that a CSRS retiree doesn't receive from federal service.

The TSP employer match is 5% of salary. On a $90,000 salary over 30 years, assuming the employee captures the full match, that's $135,000 in employer contributions before any investment growth. At a modest 6% annual return over 30 years, even $4,500 per year in employer contributions compounds to roughly $357,000. CSRS employees receive no employer match on TSP contributions.

Whether FERS's three-legged structure beats CSRS's single large pension depends heavily on two variables: Social Security earnings history and TSP investment behavior. An employee who maxes TSP contributions, captures the full match, and has a good Social Security record can approach CSRS-level total retirement income. An employee who contributes minimally to TSP and retires before 62 to avoid Social Security eligibility does significantly worse under FERS.

A worked example at $90,000 and 30 years

CSRS: $50,625 pension per year from day one. No Social Security from federal service. No TSP match historically.

FERS at 62: $29,700 pension per year (1.1% multiplier). Plus estimated $18,000 per year in Social Security ($1,500/month). First-year total: $47,700. Plus TSP balance available for withdrawal.

Year-one income difference: CSRS wins by $2,925. But FERS includes a TSP balance that CSRS doesn't match. After 10 years of COLA compounding (CSRS at full CPI 2.5%, FERS at diet COLA 1.5%), the CSRS pension has grown to $64,859 while the FERS pension has grown to $34,557. The CSRS lead widens over time because of the COLA structure, not just the starting pension.

The COLA difference is the sleeper issue

Both systems provide cost-of-living adjustments, but they're not the same. CSRS retirees receive the full CPI increase every year. FERS retirees receive a reduced COLA under the "diet COLA" rule: when CPI exceeds 2%, FERS retirees get 1 percentage point less than CPI. When CPI is exactly 3%, CSRS gets 3%, FERS gets 2%.

The 2021-2023 inflation surge made this difference tangible. In 2022, CPI ran at 8.7% for Social Security purposes. CSRS retirees received 8.7%. FERS retirees received 7.7%. One percentage point on a $50,000 pension is $500 per year, every year going forward, permanently compounding. After a decade of consistent 3% inflation, a CSRS retiree who started at $50,000 has $67,195. A FERS retiree who started at the same amount has $62,429. That's nearly $5,000 per year in lost purchasing power, and it keeps growing.

Over a 25-year retirement with 2.5% average inflation, the COLA gap compounds to a meaningful difference in total lifetime income. The calculator above uses 2.5% CPI with a 1.5% effective FERS COLA and 2.5% CSRS COLA to show you what this looks like across your specific numbers.

CSRS Offset: the hybrid nobody talks about

Some employees are under CSRS Offset, not pure CSRS or FERS. CSRS Offset applies to employees who left federal service before 1984, paid into Social Security during that break, and returned to federal service after 1984. They're technically in CSRS but pay Social Security taxes on their federal wages.

When a CSRS Offset employee reaches Social Security eligibility, their CSRS pension is reduced by the amount of Social Security they earned from federal service. It's called an offset because the two benefits partially offset each other. The total retirement income is roughly the same as pure CSRS, but it comes from two sources rather than one.

This matters because CSRS Offset employees are subject to WEP and GPO rules. The Social Security Fairness Act of January 2025 repealed both, potentially increasing Social Security benefits for CSRS Offset retirees who had previously been reduced.

WEP, GPO, and the 2025 repeal

The Windfall Elimination Provision reduced Social Security benefits for people who received pensions from non-Social-Security-covered work (like CSRS federal employment) but also had Social Security credits from other jobs. The Government Pension Offset reduced Social Security spousal and survivor benefits for the same population.

Both provisions were repealed by the Social Security Fairness Act, signed January 5, 2025. CSRS retirees who had Social Security benefits reduced under WEP or GPO are now receiving higher Social Security payments retroactive to January 2024. SSA estimates roughly 3.2 million retirees were affected. If you're a CSRS retiree who also has Social Security benefits, you should have received a retroactive payment and higher ongoing benefits. Contact SSA directly if you haven't seen the adjustment.

Survivorship under each plan

Both CSRS and FERS offer survivor annuity elections. Under FERS, the maximum survivor benefit is 50% of the unreduced annuity, costing 10% of the pension. A $30,000 FERS pension becomes a $27,000 pension to you, with a $15,000 survivor annuity for a qualifying spouse. Under CSRS, the survivor annuity is 55% of the unreduced annuity, and the cost is 2.5% on the first $3,600 of annuity plus 10% on the remainder.

The CSRS survivor benefit is more generous as a percentage of the original pension. On a $50,625 CSRS pension, the survivor would receive $27,844 annually. The FERS survivor on a $30,000 pension gets $15,000. The absolute amounts reflect the underlying pension difference, but CSRS's 55% survivor fraction beats FERS's 50%.