Military Buy Back Calculator
Work out what it costs to buy back your military time for FERS or CSRS, and what it pays back. Enter your military basic pay by year and the date you started federal service. The calculator shows the deposit, the OPM interest if you wait, the deadline to avoid interest, the extra pension and the break-even. The deposit is exact; the interest is an estimate that follows OPM's Handbook method.
Latest OPM interest rate: 4.25% for 2026. As of October 24, 2026, OPM had not published a rate for 2027; the calculator never treats a later rate as known.
Maintained by Archie Chang · OPM Handbook, letters, forms and statutes checked October 24, 2026 · Methodology & sources
Military buy back cost and payoff
What you would pay
- Deposit (principal)
- $1,755.00
- exact: OPM percentage of basic pay, rounded once per continuous period
- Interest (estimate)
- $569.78
- 12 interest postings
- Total to pay on March 1, 2027
- $2,324.78
- principal is exact; interest is an estimate
At least one interest date falls between 1998 and 2016. We could not check the day count for those years against an OPM table, so the interest is approximate.
| Year | Basic pay | Percent | Product |
|---|---|---|---|
| 2004 | $18,000.00 | 3% | $540.00 |
| Deposit for this period, to the nearest dollar | $540 | ||
| 2005 | $19,500.00 | 3% | $585.00 |
| Deposit for this period, to the nearest dollar | $585 | ||
| 2006 | $21,000.00 | 3% | $630.00 |
| Deposit for this period, to the nearest dollar | $630 | ||
Interest-free deadline
Interest begins to accrue on June 4, 2014 but is not charged until your first interest accrual date, June 4, 2015. Pay in full so the agency has the money by June 3, 2015 (the last business day before that date) and you owe the deposit alone. Each year after that a new interest posting compounds onto what is still unpaid. Federal holidays are not modeled, so pay a few days early.
| Interest accrual date | Balance before | Composite rate | Interest | Balance after |
|---|---|---|---|---|
| June 4, 2015 | $1,755.00 | 1.784% | $31.31 | $1,786.31 |
| June 4, 2016 | $1,786.31 | 2.000% | $35.73 | $1,822.04 |
| June 4, 2017 | $1,822.04 | 1.947% | $35.48 | $1,857.52 |
| June 4, 2018 | $1,857.52 | 1.981% | $36.80 | $1,894.32 |
| June 4, 2019 | $1,894.32 | 2.391% | $45.29 | $1,939.61 |
| June 4, 2020 | $1,939.61 | 2.538% | $49.23 | $1,988.84 |
| June 4, 2021 | $1,988.84 | 1.878% | $37.35 | $2,026.19 |
| June 4, 2022 | $2,026.19 | 1.375% | $27.86 | $2,054.05 |
| June 4, 2023 | $2,054.05 | 1.588% | $32.62 | $2,086.67 |
| June 4, 2024 | $2,086.67 | 2.672% | $55.76 | $2,142.43 |
| June 4, 2025 | $2,142.43 | 4.016% | $86.04 | $2,228.47 |
| June 4, 2026 | $2,228.47 | 4.322% | $96.31 | $2,324.78 |
What it adds to your annuity
- Credited military service
- 3 yr 0 mo
- Added basic annuity per year
- $3,135.00
- about $261.25 a month
- Break-even
- 0.7 years
- total cost / added annuity, before COLAs and taxes
- Annuity with the military months: $34,485.00 a year at 1.1% of high-3 per year; without: $31,350.00 at 1.1%.
- Unreduced. If you retire under MRA + 10 the added amount is reduced by the same age reduction, and a survivor benefit costs 5% or 10% of it.
- The FERS annuity supplement does not grow, except for military service during leave without pay from your civilian job (5 CFR 842.504).
- If you receive military retired pay you must waive it to use this service, unless it is awarded for a service-connected disability "incurred in combat with an enemy of the United States" or "caused by an instrumentality of war and incurred in line of duty during a period of war", or under chapter 1223 of title 10 (5 U.S.C. 8411(c)(2)). A deposit is refunded if you keep the retired pay.
How the military deposit works
- Who pays what: active-duty service after December 31, 1956 counts only if you pay a deposit to your agency: 3% of basic pay under FERS (5 U.S.C. 8422(e)) and 7% under CSRS (5 U.S.C. 8334(j)), plus interest if you wait. Each continuous period of service is rounded once to the nearest dollar (5 CFR 842.307(d) defines a distinct period; Handbook 23B3.1-1).
- FERS needs the deposit for eligibility too. Unpaid military service counts for nothing under FERS (Handbook 23B1.1-3). CSRS employees first hired before October 1, 1982 can sometimes count the service without a deposit but face a reduction at 62; this page assumes you pay.
- Deadline: pay in full to your agency before your last day of service (5 CFR 842.307(a)(3) for FERS; BAL 26-101: all military deposits must be paid in full to the employing agency before the employee's separation for retirement). A separated employee generally cannot pay. Your agency records the payment and confirms it to OPM with your retirement papers.
- Interest: none if paid in full before your first interest accrual date, three years after you first became an employee following the military service (FERS no earlier than January 1, 1987; CSRS no earlier than October 1, 1983). The Handbook calls this "in effect, a 3-year interest-free period" (23B3.1-2A). After that OPM adds a year of interest on each accrual date and compounds it. Interest runs on the unpaid balance only, so payments in installments cut the interest.
- Value: 1% of high-3 per year of FERS service (1.1% at 62 or older with 20 years), or 2% per year in CSRS above 10 years. The military months count toward the 20 years, which can lift all your service to 1.1%.
OPM Handbook worked example: $6,430 of basic pay
Chapter 23 of OPM's CSRS and FERS Handbook uses $6,430 of basic pay. At FERS 3% that is $192.90, so the deposit is $193.00; at CSRS 7% it is $450.10, so the deposit is $450.00. For the CSRS example, the Handbook then adds interest on interest accrual dates October 1, 1986 to 1989 with composite rates of 11.594%, 9.531%, 8.531% and 8.938% (section 23A3.1-5H):
| Accrual date | Deposit amount | Rate | Interest | Total due |
|---|---|---|---|---|
| 1986-10-01 | $450.00 | 11.594% | $52.17 | $502.17 |
| 1987-10-01 | $502.17 | 9.531% | $47.86 | $550.03 |
| 1988-10-01 | $550.03 | 8.531% | $46.92 | $596.95 |
| 1989-10-01 | $596.95 | 8.938% | $53.36 | $650.31 |
With payments of $100 on June 1, 1988 and $150 on September 17, 1989, the Handbook (section 23A3.1-5I) shows the balance falling to $368.67 after the October 1, 1989 posting. The calculator reproduces both tables to the cent. The tests also check the composite rate method against OPM's published 2017 and 2026 composite tables.
OPM military deposit interest rates by year
OPM sets one rate for each calendar year and applies it to CSRS and FERS alike. The rate on an interest accrual date blends two calendar years, as explained in the FAQ below. Rates before 1985 were 3%, and interest could not begin before October 1, 1985.
| Year | Rate | OPM source |
|---|---|---|
| 2026 | 4.25% | BAL 26-101 |
| 2025 | 4.375% | BAL 25-101 |
| 2024 | 3.75% | BAL 24-101 |
| 2023 | 1.875% | BAL 23-101 |
| 2022 | 1.375% | BAL 22-102 |
| 2021 | 1.375% | BAL 21-103 |
| 2020 | 2.25% | BAL 20-101 |
| 2019 | 2.75% | BAL 19-101 |
| 2018 | 2.125% | BAL 18-101 |
| 2017 | 1.875% | BAL 17-102 |
| 2016 | 2% | BAL 16-101 |
| 2015 | 2% | BAL 15-101 |
| 2014 | 1.625% | BAL 14-101 |
| 2013 | 1.625% | BAL 13-101 |
| 2012 | 2.25% | BAL 12-101 |
| 2011 | 2.75% | BAL 11-101 |
| 2010 | 3.125% | BAL 10-103 |
| 2009 | 3.875% | BAL 09-101 |
| 2008 | 4.75% | BAL 08-102 |
| 2007 | 4.875% | BAL 07-101 |
| 2006 | 4.125% | BAL 06-101 |
| 2005 | 4.375% | OPM Form 1514 |
| 2004 | 3.875% | OPM Form 1514 |
| 2003 | 5% | OPM Form 1514 |
| 2002 | 5.5% | OPM Form 1514 |
| 2001 | 6.375% | OPM Form 1514 |
| 2000 | 5.875% | OPM Form 1514 |
| 1999 | 5.75% | OPM Form 1514 |
| 1998 | 6.75% | OPM Form 1514 |
| 1997 | 6.875% | OPM Form 1514 |
| 1996 | 6.875% | OPM Form 1514 |
| 1995 | 7% | OPM Form 1514 |
| 1994 | 6.25% | OPM Form 1514 |
| 1993 | 7.125% | OPM Form 1514 |
| 1992 | 8.125% | OPM Form 1514 |
| 1991 | 8.625% | OPM Form 1514 |
| 1990 | 8.75% | OPM Form 1514 |
| 1989 | 9.125% | OPM Form 1514 |
| 1988 | 8.375% | OPM Form 1514 |
| 1987 | 9% | OPM Form 1514 |
| 1986 | 11.125% | OPM Form 1514 |
| 1985 | 13% | OPM Form 1514 |
The 2026 rate is the newest OPM has published. As of October 24, 2026, OPM had not published a 2027 rate; if a payment date needs it, the calculator says so and uses the 2026 rate only as a labeled placeholder.
How to buy back military time: the process
- Get your military pay estimate. Send form RI 20-97 and your DD 214 to the military pay center (DFAS handles the Army, Navy, Air Force and Marine Corps). Tax and Social Security earnings statements cannot be used because they include allowances.
- Apply through your agency. FERS employees use SF 3108 with SF 3108A; CSRS employees use SF 2803. The agency computes the deposit, the interest accrual date and the balance.
- Pay the agency before you separate. A lump sum before the interest date avoids interest. Installments are allowed (FERS: 5 CFR 842.307(c)(3), agencies need not take installments under $50; CSRS: 5 CFR 831.2107(a)(2), by allotment or otherwise).
- Waive military retired pay if you have it, by writing DFAS, and attach a copy to your retirement application.
What is exact, what is an estimate, and what is left out
Exact: the deposit percentages, the rounding to the dollar once per continuous period (rows you mark as continuing are summed first), OPM's published yearly rates, and the dates that start interest. The Handbook's worked examples above are reproduced to the cent.
Estimate: the interest. OPM's method (posting on the accrual date, the balance the day before, a composite of two years' rates) is documented, but the day count behind the composite rate is inferred from OPM's published tables. The calculator matches every cell of OPM's 2025 and 2026 tables and the Handbook's 1986 to 1997 tables we checked, but we could not check interest dates from 1998 to 2016, which the calculator flags as approximate. Your agency's figure is the one that counts. Payment dates are judged on weekends only, not federal holidays. The added annuity is the unreduced basic annuity; it ignores COLAs, taxes, survivor reductions, the MRA + 10 age reduction and special-category rates.
Not modeled:
- The USERRA alternative calculation, which can cap the deposit at what would have been withheld from civilian pay (Handbook 23B3.1-1)
- Employees who transferred from CSRS to FERS with a CSRS component, and CSRS employees first hired before October 1, 1982
- Survivor deposits, refunds and alternative annuity elections, and deposits made after a separation
- Installment schedules (the calculator assumes one lump sum on the payment date) and deposits paid in agency error cases
- Taxes, TSP and the value of the money you would otherwise invest
Related: FERS retirement calculator for the full annuity and supplement, and the military pay chart for basic pay tables.
Military buy back questions
How much does it cost to buy back military time?
Under FERS the deposit is 3% of the military basic pay you earned, and under CSRS it is 7%. Service in 1999 and 2000 uses slightly higher percentages (3.25% and 3.4% for FERS, 7.25% and 7.4% for CSRS). Basic pay does not include allowances, flight pay or combat pay. Interest begins to accrue two years after you first became an employee following the military service, but OPM posts it only on your interest accrual date one year later, which the Handbook describes as "in effect, a 3-year interest-free period" if the deposit is paid in full before that date (Handbook 23A3.1-5 and 23B3.1-2). Count from the day of first becoming an employee after the military service, no earlier than January 1, 1987 for FERS or October 1, 1983 for CSRS. After that, interest compounds each year at OPM's variable rate. On $20,000 of basic pay a FERS deposit is $600 before interest.
Is there an interest-free period for the military deposit?
Yes. By statute interest starts two years after you first become an employee following the military service (5 U.S.C. 8422(e)(2), 8334(j)(2)), and if the service came after you were hired, the clock starts when you return to covered work. OPM posts that interest only on the interest accrual date, one year later, on the balance the day before. If the agency has your full payment by the last business day before that date, you owe no interest. OPM's own regulation gives the example of a FERS employee covered March 1, 1988: interest begins March 1, 1990, yet no interest is due if the deposit is completed by February 28, 1991 (5 CFR 842.307(b)(4)). Employees covered before 1987 are treated as covered on January 1, 1987 under FERS, and CSRS employees hired before October 1, 1983 as hired on that date.
What happens to my FERS retirement if I do not buy back my military time?
The service does not count at all. For FERS, post-1956 active-duty service counts both for eligibility and for the annuity amount only if you pay the deposit before you separate (5 U.S.C. 8411(c); Handbook 23B1.1-3). OPM's example: a 58-year-old with 8 civilian years and 3 military years can retire under MRA + 10 only if the deposit is paid; without it, he must wait until 62.
How much does buying back military time add to my pension?
Each year of credited military service adds 1% of your high-3 average salary per year to the FERS basic annuity, or 1.1% per year if you separate at 62 or older with at least 20 years of service (5 U.S.C. 8415). The military years count toward those 20 years, so they can lift all of your service to 1.1%. Under CSRS each year adds 2% of high-3 once you have more than 10 years (1.5% and 1.75% for the first 10), up to an 80% cap. Divide your total cost by the yearly increase for a simple break-even.
Does military buy back increase the FERS supplement?
Generally no. The supplement is based on your Social Security estimate times your FERS service divided by 40, and OPM's rule excludes military service unless it was performed during leave without pay from your civilian job (5 CFR 842.504). The deposit does raise the basic annuity, helps you meet age and service requirements, and raises a survivor annuity that is a percentage of it.
Do I have to waive my military retired pay?
Usually yes. If you receive military retired pay, the service it is based on cannot be credited unless the retired pay is awarded based on a service-connected disability "incurred in combat with an enemy of the United States" or "caused by an instrumentality of war and incurred in line of duty during a period of war as defined by section 1101 of title 38," or under chapter 1223 of title 10 (5 U.S.C. 8411(c)(2)). If you keep the retired pay, OPM refunds the deposit. OPM asks you to send the waiver request to DFAS 30 days before your planned retirement and attach a copy to your retirement application (BAL 26-101).
How do I buy back my military time?
Ask your human resources office for SF 3108 and SF 3108A (FERS) or SF 2803 (CSRS), and send your DD 214. Request your military basic pay by year on RI 20-97 from the military pay center (DFAS for the Army, Navy, Air Force and Marine Corps). Your agency computes the deposit, interest and interest accrual date, and you pay the agency, in a lump sum or in installments (5 CFR 842.307(c)(3) for FERS; 5 CFR 831.2107(a)(2) for CSRS). Agencies are not required to take FERS installments under $50. A current employee must complete the deposit before separation (5 CFR 842.307(a)(3); BAL 26-101), so pay in full before your last day; your agency records the payment and confirms it to OPM with your retirement papers. Any deposit still unpaid when you separate is refunded and that service is not credited.
Can I buy back military time at USPS?
Postal employees are covered by FERS or CSRS, so the same deposit percentages, interest rates and rules apply, and the deposit is paid to your employing agency, which is USPS. This page does not cover USPS paperwork; ask your USPS human resources office how to submit the forms and set up payments.
What interest rate does OPM use for military buy back?
OPM uses the variable rate Treasury sets each calendar year. The newest rate OPM has published is 4.25% for 2026 (BAL 26-101 and BAL 26-301). The rate charged on an interest accrual date is a composite: the previous calendar year's rate for the part of the prior 12 months that fell in that year, and the current year's rate for the rest. For example, on October 1, 2017 OPM applied 1.906%: three months at 2.0% and nine months at 1.875%.
Authoritative sources: Handbook chapter 23 · Handbook chapter 22 · OPM Form 1514 · OPM benefits letters · BAL 26-101 · BAL 26-301 · BAL 16-307 · 5 U.S.C. 8411 · 5 U.S.C. 8422 · 5 U.S.C. 8334 · 5 U.S.C. 8339 · 5 U.S.C. 8415 · 5 CFR 842.307 · 5 CFR 842.504