The Federal Employees Retirement System (FERS) basic annuity is a pension paid for life from a formula, while the Thrift Savings Plan (TSP) is an investment account you fund yourself with an agency match; they are two legs of the same retirement system. The FERS basic annuity is a defined-benefit pension managed and paid monthly for life by the Office of Personnel Management (OPM) Retirement Services using a statutory formula. The Thrift Savings Plan (TSP) is a defined-contribution investment account funded by employee deductions and agency matching contributions, where the final balance depends on personal contributions and market performance.
Under FERS, federal civilian employees have both the pension and access to the TSP, alongside Social Security. The open questions are how much basic pay to put into the TSP and how to draw on the annuity and the account together in retirement.
FERS pension (basic annuity) vs Thrift Savings Plan (TSP): Side-by-Side Comparison
| Factor | FERS pension (basic annuity) | Thrift Savings Plan (TSP) |
|---|---|---|
| Benefit structure | Defined-benefit pension paid for life by OPM | Defined-contribution retirement account with an account balance |
| Funding source | Employee pension contribution (0.8%, 3.1%, or 4.4% of basic pay, by hire date) | Voluntary employee elective deferrals plus up to 5% total agency contributions |
| Benefit calculation | Calculated by formula: High-3 average salary multiplied by years of creditable service and a statutory multiplier | Balance depends on contributions, time, and investment returns |
| Investment and market risk | Benefit formula does not depend on market returns | Retiree absorbs market risk; balances fluctuate based on contributions and market returns |
| Employee management control | Retiree chooses retirement timing and survivor election, while OPM calculates the formula amount | You set your contribution and choose Traditional or Roth |
| Earliest withdrawal access | Payable immediately at Minimum Retirement Age (MRA) with 30 years, age 60 with 20 years, or age 62 with 5 years | Withdrawals are your choice and timing |
How the Two Fit Together
FERS operates as a three-legged retirement system providing three separate income streams. The first leg is the defined-benefit FERS basic annuity, which delivers monthly payments for life. The second leg is Social Security, for which FERS employees pay standard payroll taxes and collect benefits under standard Social Security rules. The third leg is the TSP, which is a defined-contribution investment account. Federal workers do not choose between FERS and the TSP. Both systems operate concurrently throughout a civilian career. A federal employee under FERS receives both; the practical decision is how much to contribute to the TSP and how to coordinate withdrawals with the annuity in retirement.
How the FERS Basic Annuity Works
The FERS basic annuity is an employer-sponsored pension that pays a set dollar amount each month starting on your retirement date and continuing for the rest of your life. The monthly payment is set by a formula: your High-3 average salary multiplied by your total years and months of creditable service, multiplied by a statutory percentage multiplier. You can run individual career numbers directly using the FERS calculator or read the guide on FERS retirement.
Your High-3 average salary equals the highest consecutive 36 months of basic pay earned during your federal career. Creditable service includes your total completed civilian service, any active-duty military service successfully purchased through a deposit, and unused sick leave.
The standard FERS multiplier is 1.0% for each year of service. If you retire at age 62 or older with at least 20 years of service, that multiplier increases to 1.1% for every year of creditable service. Mandatory employee contributions to fund this pension depend on hire date: employees hired before 2013 contribute 0.8% of basic pay, employees hired in 2013 under FERS-RAE contribute 3.1%, and employees hired in 2014 or later under FERS-FRAE contribute 4.4%. The pension benefit paid upon retirement is identical across all three contribution tiers.
Eligibility for an unreduced immediate basic annuity requires meeting specific age and service benchmarks. Employees can retire at their Minimum Retirement Age (MRA) with 30 years of service, at age 60 with 20 years of service, or at age 62 with 5 years of service. MRA is age 57 for individuals born in 1970 or later, age 56 for those born between 1953 and 1964, and age 55 for those born before 1948. Retiring at your MRA with at least 10 years results in a 5% benefit reduction for each year you are under age 62, or payments can be postponed.
Cost-of-living adjustments (COLA) on the FERS basic annuity do not begin until age 62 for most civilian retirees. Once eligible, the annual increase is indexed to the Consumer Price Index (CPI): if the CPI increases by 2.0% or less, your annuity increases by the full CPI rate; if the CPI increases between 2.0% and 3.0%, the increase is capped at 2.0%; and if the CPI rises above 3.0%, the adjustment equals the CPI minus 1.0%.
How the Thrift Savings Plan Works
The Thrift Savings Plan is a defined-contribution account that is funded through payroll contributions and agency contributions. Unlike the fixed pension, the TSP provides an account balance that you own, invest, and control. Withdrawals are your choice and timing.
Federal agencies provide automatic and matching contributions to FERS civilian employees who participate in the TSP. Your employing agency automatically deposits an amount equal to 1.0% of your basic pay each pay period, even if you contribute nothing of your own. When you elect to contribute your own pay, the agency matches up to an additional 4.0%. By contributing at least 5.0% of your basic pay each pay period, you capture the full 5.0% agency contribution.
The TSP is available in Traditional and Roth. The guide to TSP Roth vs Traditional details each option.
For 2026, the IRS elective deferral limit is $24,500 under IRS Notice 25-67, up from $23,500 in 2025. Agency automatic and matching contributions do not count against this $24,500 limit; they count toward the broader annual additions limit of $72,000. Employees age 50 and older can make an additional catch-up contribution of $8,000 in 2026, for a total elective deferral limit of $32,500. Employees between the ages of 60 and 63 qualify for an enhanced catch-up contribution limit of $11,250, allowing total elective deferrals of $35,750. Review the guide on TSP contribution limits for full details. The IRA limit for 2026 is $7,000, or $8,000 at 50 or older, separate from the TSP limit, as explained in the guide comparing the TSP vs IRA.
Worked Examples of the FERS Pension
Examples show how the FERS basic annuity formula calculates annual pension payouts across different career lengths and retirement ages. Consider a GS-13 employee who retires at their Minimum Retirement Age of 57 with 25 years of creditable service and a High-3 average salary of $90,000. Under the standard 1.0% multiplier, the calculation is $90,000 multiplied by 25 years multiplied by 0.010, resulting in an annual pension of $22,500, or $1,875 per month. That figure is before any reduction; the unreduced path at the minimum retirement age requires 30 years. The FERS Annuity Supplement is paid in addition until 62.
A GS-14 employee working a longer career shows the effect of higher service years and the enhanced age-62 multiplier. If this employee retires at age 62 with 32 years of service and a High-3 salary of $115,000, their multiplier increases from 1.0% to 1.1%. The calculation is $115,000 multiplied by 32 years multiplied by 0.011, yielding an annual pension of $40,480, or $3,373 per month. If this same employee had retired at age 60 with 30 years of service, the standard 1.0% multiplier would have applied: $115,000 multiplied by 30 multiplied by 0.010 produces $34,500 per year. Working two additional years to reach age 62 adds $5,980 a year for life.
A mid-career employee retiring at age 60 with 20 years of service and a High-3 of $80,000 receives $80,000 multiplied by 20 multiplied by 0.010, which equals $16,000 annually ($1,333 monthly). If that worker remains in service until age 62 with 22 years of service, the multiplier shifts to 1.1%: $80,000 multiplied by 22 multiplied by 0.011 produces $19,360 per year ($1,613 monthly). That choice adds $3,360 in annual income for life.
Unlike the pension, your ultimate TSP balance cannot be determined by a fixed formula because it depends on your contributions, time, and investment returns. Employees can model different savings scenarios using the TSP withdrawal calculator to estimate monthly drawdown income alongside their basic annuity.
Buying Back Military Service
Prior military service does not transfer into your FERS basic annuity calculation automatically, but federal law provides a buy-back mechanism to credit active-duty time toward your civilian pension. Buying back military time increases your creditable years of service, raising your pension for life.
For active-duty service performed after 1982, an employee must make a deposit equal to 3.0% of their military basic pay earned during that active duty, plus any applicable interest accrued after an initial interest-free grace period of two to three years following the start of federal civilian service. For employees covered under the older Civil Service Retirement System (CSRS), the required deposit rate is 7.0%. Active-duty service performed before 1982 may be creditable without a deposit under certain statutory rules.
Every completed year of military service bought back adds 1.0% of your High-3 average salary to your annual FERS pension, or 1.1% if you retire at age 62 or older with at least 20 total years of service. A typical four-year military enlistment with $20,000 in average annual basic pay costs roughly $2,400 to buy back. If an employee with a $100,000 High-3 salary adds those four military years to a 30-year FERS civilian career, their annual pension increases by $4,000 every year for life. The financial break-even on the buy-back deposit is achieved within the first year or two of retirement.
For veterans who served under the uniformed services Blended Retirement System (BRS), the military also provided a 1.0% automatic agency contribution and up to 4.0% matching in a uniformed services TSP account. Learn more about veteran benefits in the military retirement hub.
Drawing On Each Benefit in Retirement
The FERS basic annuity is administered directly by OPM Retirement Services and paid monthly for life. This payment continues at the calculated rate for your lifetime, subject to applicable survivor benefit reductions.
Retirees can elect to provide a survivor annuity for a spouse. Electing a full survivor annuity provides the surviving spouse with 50% of the annuity after your death, funded by a 10.0% reduction in your monthly pension payment. Electing a partial survivor annuity provides a 25.0% benefit to your spouse in exchange for a 5.0% reduction in your monthly pension. Waiving the spousal survivor benefit entirely requires written spousal consent.
For eligible retirees, the FERS Annuity Supplement bridges the gap between the minimum retirement age and 62. The specific dollar amount varies; request an estimate from your agency human resources office or OPM.
The TSP provides flexible distribution choices rather than a rigid formula. TSP withdrawals are your choice and timing. Review the guide on TSP withdrawal options and the guide on the TSP annuity option.
Choosing Where to Focus Your Efforts
Where the focus belongs depends on where you stand in your federal career. The FERS basic annuity is the primary focus for employees with long careers who remain in federal service until full retirement eligibility age. Employees approaching retirement age can substantially increase their lifetime pension simply by timing their exit: delaying retirement from age 60 to age 62 with at least 20 years of service raises the multiplier from 1.0% to 1.1% across all years worked, as shown in the worked examples. The annuity is a poor strategic fit for workers planning to leave federal service after only a few years, because an employee needs at least 5 years of service at age 62 to qualify for an annuity.
The TSP matters more for short-career employees, mid-career hires, and workers who plan to leave federal service. Your TSP balance is an investment account you fund yourself. Federal employees who want the full match need to contribute at least 5.0% of basic pay to the TSP each pay period to capture the full 5.0% agency automatic and matching funds. Request a personalized FERS estimate from HR and confirm your service computation date, then work through the federal retirement guide.
Verdict: Which Should You Choose?
The FERS basic annuity and the TSP are not competing alternatives. The pension formula pays monthly income for life without depending on market returns, while the TSP value depends on employee contributions and market performance. The annuity does little for an employee who leaves federal service before 5 years, and the TSP does little for someone who does not contribute at least 5% of basic pay, since that leaves part of the agency match unclaimed. Nearing age 62 with 20 years of service shifts the focus to the higher pension multiplier.