TSP Calculator

The Thrift Savings Plan is the federal defined-contribution retirement plan authorized for service members under 5 U.S.C. § 8440e. The plan is administered by the Federal Retirement Thrift Investment Board (FRTIB), not by DFAS or the service branches. Service members participate in the same TSP vehicle as civilian federal employees, but the matching rules differ depending on retirement system eligibility — Blended Retirement System (BRS) members receive employer matching; pre-2018 High-3 members do not.

The BRS 5% match — automatic 1% plus dollar-for-dollar through 4%. Under the BRS matching rules (5 U.S.C. § 8432(c), as applied to members via § 8440e; Public Law 114-92), the Department of Defense contributes 1% of basic pay to the member's TSP regardless of whether the member contributes, beginning after 60 days of service. The member who contributes 5% or more of basic pay receives a 4% matching contribution from the government, structured as 1% match on the first 3% and 0.5% match on contributions 4-5%. The combined employer contribution at the 5% member contribution level is 5% — the "free 5%" that BRS planners universally recommend members capture before prioritizing any other savings vehicle. Contributing less than 5% leaves matching dollars on the table; a service member at 5% under BRS who reduces to 3% gives back the 0.5% match × 2% = 1% of basic pay per year.

2026 contribution limits. The IRS-set annual elective deferral limit for 2026 is $24,500 for participants under age 50, with an additional $8,000 catch-up contribution available for participants age 50 and over (and an $11,250 super catch-up for ages 60–63 under SECURE 2.0). These limits are published annually by the IRS (Revenue Procedure 2025 series) and apply uniformly to TSP and to private-sector 401(k) plans. Members who max the $24,500 limit before December 31 stop receiving the employer match for the remainder of the year because matching is calculated per pay period — front-loading contributions to hit the cap in June or July creates a back-half match gap. The FRTIB spillover provision (effective 2025) automatically extends matching to Catch-Up contributions for participants age 50+, addressing the historical "missing match" gap that affected senior enlisted and senior officers.

Combat Zone Tax Exclusion contributions. Service members in a designated combat zone under 26 U.S.C. § 112 may contribute up to the full annual additions limit ($72,000 in 2026 — well above the standard $24,500 elective deferral cap) to TSP using their tax-exempt CZTE pay. Combat-zone contributions must be designated as either Traditional (which keeps them tax-exempt on the way out, similar to Roth) or Roth. The combat-zone provision is the single highest-leverage tax-advantaged retirement vehicle available to deployed members — a 6-month combat-zone deployment can support $30,000+ of CZTE contributions on top of normal contributions, and the qualified withdrawals are tax-free.

Roth vs Traditional under BRS. Both Roth and Traditional contributions count toward the 5% match threshold; the match itself goes to a Traditional (pre-tax) bucket regardless of the member's election. Junior enlisted members typically come out ahead with Roth because their marginal tax rate in service is often lower than their projected retirement rate. Senior officers approaching O-5 to O-6 with high taxable base pay are often better served by Traditional contributions because their marginal rate in service is already elevated. The TSP recordkeeper allocates each contribution to the correct sub-account; the calculator above models both elections.

Authorities: 5 U.S.C. §§ 8432(c), 8440e (uniformed-services TSP participation and agency automatic/matching contributions); Public Law 114-92 (BRS); 26 U.S.C. §§ 112, 401, 415 (tax treatment, elective deferral limits, annual additions limit); IRS Revenue Procedure 2025 series (2026 retirement plan limits); FRTIB regulations (5 CFR Parts 1600-1690); DoD Instruction 1304.31 (BRS administration). The FRTIB tsp.gov member portal is the authoritative source for contribution status, allocation percentages, and historical fund performance.