High-3 vs BRS: military retirement math, side by side

The two formulas

The base is the same. Under 10 U.S.C. 1407, the retired pay base is the total of your 36 highest months of basic pay, whether or not consecutive, divided by 36. The Department of Defense (DoD) Financial Management Regulation (FMR, Volume 7B, chapter 3) rounds that average to the cent. For most people it is the last three years of service, which is why “High-3” stuck as the name.

The multiplier differs. 10 U.S.C. 1409(b) sets High-3 at 2.5 times your years of creditable service. For members who entered on or after January 1, 2018, or who opted in, 1409(b)(4) substitutes 2 for 2.5. Over 30 years (retiring after 2006), High-3 is 75% plus 2.5% for each year beyond 30, and BRS is 60% plus 2.0% per year, for service credited under that rule.

Months count, and pay is rounded down. Each full month beyond your whole years counts as 1/12 of a year (10 U.S.C. 1405(b) and 1409(c)). The FMR rounds the multiplier to 0.01 percentage point, using its own example: 20 years 7 months is 20.58 years, and 20.58 × 2.5 = 51.45%. The same service under BRS is 41.16%. Base times multiplier is then rounded down to the whole dollar, because 10 U.S.C. 1412 says amounts that aren’t a multiple of $1 go to the next lower dollar.

Every BRS multiplier is four-fifths of the High-3 one, because 2.0 is four-fifths of 2.5 and 60% is four-fifths of 75%. The multiplier table on DoD’s militarypay.defense.gov retirement page shows the same steps.

Worked example: an E-7 retiring at 20 years

Our calculator estimates High-36 from the 2026 pay table, with no future raises. For an E-7 retiring at exactly 20 years, the last 36 months fall in two columns of the DFAS enlisted table (effective January 1, 2026): 12 months at “Over 16”, $6,000.90, and 24 months at “Over 18”, $6,177.30.

(12 × $6,000.90 + 24 × $6,177.30) ÷ 36 = $6,118.50.

The gap is $612 a month, or $7,344 a year, before any cost-of-living adjustment (COLA). Both systems get the same COLA each December 1 (10 U.S.C. 1401a(b)(5) puts BRS on the full Consumer Price Index (CPI) increase), so the gap grows along with both amounts. The COLA guide shows how that raise is set.

The same method gives a larger gap for a longer, higher-paid career. An E-9 retiring at 30 years has a High-36 of $9,267.90, because the 2026 “Over 26” and “Over 28” rates are both $9,267.90. That is $6,950 a month under High-3 (75%) against $5,560 under BRS (60%), a gap of $1,390.

These are estimates from the 2026 tables. DFAS computes the retired pay you are actually paid, from your own pay history.

What BRS adds

Thrift Savings Plan (TSP) money from the service. Under 5 U.S.C. 8440e(e), BRS members get an automatic contribution of 1% of basic pay starting 60 days after they first enter a uniformed service, and matching contributions from 2 years and 1 day of service. Both stop when you complete 26 years. TSP.gov describes the match as dollar for dollar on the first 3% of basic pay you contribute and 50 cents on the dollar on the next 2%. Contribute 5% and the service adds 4% plus the automatic 1%.

For an E-5 at “Over 4” ($3,946.80) contributing 5%, that is $197.34 a month from you, $39.47 automatic and $157.87 matching. The TSP guide covers the 2026 limits and timing. High-3 members can contribute to the TSP too, but they get no automatic or matching contributions.

Continuation pay. 37 U.S.C. 356 requires a payment to BRS members who have completed 7 to 12 years of service and agree to serve at least 3 more. For the regular component (and Active Guard and Reserve), the payment is at least 2.5 times monthly basic pay. For the regular component, the cap is 2.5 times the monthly basic pay at 12 years of service plus, at the service’s discretion, up to 13 more months of it. Other reserve members get at least 0.5 times. Each service sets its own multiples, and you can take the payment in one lump sum or up to four payments.

The lump-sum option. At retirement, BRS members (other than disability retirees) can take 25% or 50% of their retired pay up to Social Security full retirement age as a discounted lump sum. The lump-sum guide runs this E-7’s numbers through DoD’s method.

Who is in which system

The date you first entered a uniformed service decides it (DoD calls it DIEMS or DIEUS). DoD’s militarypay.defense.gov lists the cases (since September 2025, DoD pages also use the name Department of War):

• Entered on or after January 1, 2018: BRS, automatically.
• Entered September 8, 1980 through December 31, 2017: High-3, unless you opted into BRS or took the Career Status Bonus (below).
• Opted in during 2018: members serving on December 31, 2017 with fewer than 12 years of service (reserve members: fewer than 4,320 retirement points) could elect BRS during calendar year 2018. 10 U.S.C. 1409(b)(4)(C) allowed later windows only in narrow cases, such as hardship extensions or a break in service during 2018.
• Entered before September 8, 1980: Final Pay, 2.5% per year times final basic pay.

The entry date is fixed. DoD says academy cadets start it on the day they report, and enlistees on the day they entered the delayed entry program. Leaving and rejoining doesn’t reset it.

REDUX and the Career Status Bonus (CSB) are history for new decisions. Members who entered after July 31, 1986 could take a $30,000 bonus at 15 years. In return, their multiplier dropped 1 percentage point for each year short of 30 (40% at 20 years), and their yearly COLA was 1 point lower, with a one-time catch-up at 62. DoD says eligibility to elect the CSB ended on December 31, 2017.

What the side-by-side doesn’t show

The monthly comparison only covers the defined benefit. Whether BRS’s TSP money makes up the lower multiplier depends on what you contribute, whether you stay 20 years, when you leave and what the markets do. Those are things no table settles, and our calculators don’t project fund returns.

What the rules do settle: neither system’s monthly check pays anything to someone who leaves before qualifying for retirement, while BRS automatic and matching contributions already made stay in that member’s TSP account (the automatic 1% is subject to TSP’s vesting rule). And for anyone who does retire, the BRS multiplier stays four-fifths of the High-3 one.

If you are weighing a BRS-related decision, such as your TSP percentage, continuation pay or the lump sum, the personal financial counselor on your installation (through its family support or readiness center) can go through your numbers with you at no cost.

Next step

Put your grade, years and months, or your own High-36, into the military retirement calculator. It shows both systems side by side with the rounding above, and the BRS lump-sum options.