FERS vs CSRS: How the Two Federal Retirement Systems Differ

CSRS is the original federal retirement system, covering most employees first hired before 1984, and it pays a larger stand-alone annuity without Social Security. FERS covers employees hired from 1984 onward and splits retirement income across three parts: a smaller basic annuity, Social Security, and the Thrift Savings Plan with agency matching.

Who is in which system

Most federal employees first hired before 1984 were covered by the Civil Service Retirement System. Employees first hired after 1983 are generally covered by the Federal Employees Retirement System, which took effect in 1987. Open seasons in 1987 and 1998 allowed CSRS employees to transfer to FERS, so some long-career employees are in FERS despite an early start date, and some have service under both systems.

A third group, CSRS Offset, generally covers people with a break in service who were brought into Social Security while keeping CSRS. Your SF-50 shows your retirement plan code. Confirm it before relying on any comparison, because every later number depends on it.

How the annuity is calculated

CSRS pays 1.5 percent of your high-3 average salary for each of your first five years of service, 1.75 percent for years six through ten, and 2 percent for each year after that, up to a maximum of 80 percent of high-3. A 30-year CSRS career works out to roughly 56 percent of high-3.

The FERS basic annuity pays 1 percent of high-3 for each year of service, or 1.1 percent if you retire at 62 or later with at least 20 years. A 30-year FERS career retiring at 62 works out to 33 percent of high-3. The gap is intentional. FERS was designed so that Social Security and the TSP would carry the share of retirement income that the smaller annuity does not.

OPM publishes the formulas, including the split computation for employees with service under both systems, on its FERS computation page and its CSRS information page. Those are the sources to check before relying on any estimate, including the examples above.

Social Security and the TSP

FERS employees pay Social Security tax on their federal pay, so they earn Social Security benefits alongside the annuity. CSRS employees generally did not, so any Social Security benefit comes from other covered work or from a spouse's record. Until January 2025 two provisions, the Windfall Elimination Provision and the Government Pension Offset, reduced those benefits for many CSRS retirees. Both were repealed by the Social Security Fairness Act, which is covered in detail in how Social Security coordinates with a federal pension.

Both groups can contribute to the Thrift Savings Plan, but only FERS employees receive agency contributions: an automatic 1 percent of pay, plus matching contributions on the first 5 percent the employee contributes. For a FERS employee the TSP is a core part of retirement income. For a CSRS employee it is a supplement to an annuity that already covers more.

Cost-of-living adjustments

CSRS annuities receive the full cost-of-living adjustment based on the Consumer Price Index. FERS annuity adjustments are reduced when inflation runs above 2 percent: the full increase applies when inflation is 2 percent or less, the adjustment is held at 2 percent when inflation is between 2 and 3 percent, and it is one percentage point less than inflation above 3 percent. Most FERS retirees also do not receive adjustments on the basic annuity until age 62, with exceptions for certain special-category, disability and survivor annuities. Social Security adjustments apply separately to both groups.

This page is general information, not tax or legal advice. FERS, CSRS, Social Security and Thrift Savings Plan rules are set by federal agencies and change over time. Confirm every figure, formula and eligibility rule with OPM, the Social Security Administration or your agency benefits office before acting.

Retirement eligibility and survivor elections

CSRS employees can generally retire with an immediate, unreduced annuity at 55 with 30 years of service, at 60 with 20, or at 62 with 5. FERS uses a minimum retirement age between 55 and 57 depending on birth year: unreduced at that age with 30 years, at 60 with 20, or at 62 with 5. FERS also allows retirement at the minimum retirement age with 10 years, with the annuity reduced for each year under 62 unless it is postponed. FERS employees who retire before 62 with an unreduced annuity may also qualify for the annuity supplement until 62.

The survivor election works differently too. A FERS retiree can elect a full survivor annuity of 50 percent, which reduces the annuity by 10 percent, or a partial survivor annuity of 25 percent, which reduces it by 5 percent. A CSRS retiree can provide a survivor annuity of up to 55 percent, with a reduction that comes to just under 10 percent for most retirees. These elections are difficult or impossible to change later, which is why they are covered in FEHB, FEGLI and survivor elections.

What this means for planning

For a FERS household, retirement income is a coordination problem. The annuity, Social Security and the TSP have to be timed together: when to claim, how much to draw from the TSP in the years before claiming, and whether the supplement covers part of that gap. Our article on TSP rollover options for Kansas City federal employees covers the withdrawal side.

For a CSRS household, the larger annuity usually covers more of the essential spending, so the questions shift toward the survivor election, how the annuity is taxed, how a Social Security benefit from other work fits now that WEP and GPO are gone, and how any TSP balance is drawn down. In both cases the system code on the SF-50 is the starting point, not a detail.

Federal households in Mission Hills

Mission Hills, laid out by developer J.C. Nichols in the early twentieth century, sits just north of Prairie Village along the state line. For a Mission Hills household with a federal career on one side of the table, the first question we ask is which system appears on the SF-50, because the annuity, the Social Security estimate and the role of the TSP all follow from it. From there our federal employee retirement planning lays out the annuity, Social Security and the TSP year by year, alongside your agency benefits office rather than in place of it. See the communities we serve across the Kansas City area.

CFG Wealth Management Inc. is an independent firm based in Prairie Village, Kansas, led by LaMont Chandler, CRD 2794744. We are not affiliated with cfgwmt.com or with any other firm operating under a similar name. LaMont holds FINRA Series 7, 24 and NASAA Series 63, 65 registrations and has been registered in the securities industry since 1996. He is registered in Kansas, Missouri, Texas and Idaho. Securities and advisory services are offered through Madison Avenue Securities, LLC, member FINRA and SIPC, and a registered investment advisor. CFG Wealth Management Inc. and Madison Avenue Securities are not affiliated companies. His record is available on FINRA BrokerCheck.

Common questions

Where this connects

• Federal employee retirement planning coordinates FERS or CSRS, TSP and Social Security
• How Social Security Coordinates With a Federal Pension
• FEHB, FEGLI and survivor elections covers the irreversible choices
• What to look for in a federal retirement advisor
• More retirement planning insights