2027 TSP Limit: $25,000 or $25,500? It Turns on 0.04%

Last Updated: October 5, 2026 Reading Time: 8 min

The 2027 TSP contribution limit is not official yet, but two of the three inflation readings that set it are in. By our calculation from the tax code and Bureau of Labor Statistics data, the limit will be $25,500 if September's inflation index comes in at about 335.12 or higher, and $25,000 if it does not. That is a rise of about 0.04% from August. The number comes out October 14. The IRS makes it official later, usually in November.

2026 figures are from the IRS. 2027 figures are FedTools projections from the indexing formulas in the tax code and BLS CPI-U data through August 2026. None is confirmed. We will update this table on October 14 and again when the IRS publishes.

The benefits consulting firms land in the same place. Milliman projects $25,500 and flags $25,000 if September inflation comes in under 0.04%. Mercer also projects $25,500.

Why It Comes Down to One Inflation Reading

The limit is set by formula. 26 U.S.C. § 402(g) starts with $15,000 and grows it by inflation since the third quarter of 2005. The increase is rounded down to the nearest $500.

The rounding decides this year's limit. The comparison uses the average CPI-U for July, August and September. Two of those three months are in:

• July 2026: 333.918
• August 2026: 334.980
• September 2026: due October 14

FedTools calculation from BLS series CUUR0000SA0 and the statutory base. The same method reproduces all five of the IRS's 2026 figures to the dollar. If Treasury rounds the quarterly averages to three decimals first, the line is 335.123. Only a September reading of exactly 335.122 would make that difference matter.

For context, the August-to-September change was larger than 0.042% in each of the five years we checked: 2001, 2005, 2023, 2024 and 2025. The index also fell from 335.123 in May 2026 to 333.918 in July, so a rise is not guaranteed.

By the same math, the limit would stay at $24,500 only if the index fell about 5.8% in a month, so $25,000 is the realistic floor.

FedTools calculation: the annual target divided by 26, rounded up to the next whole dollar. All 2027 targets are projections.

The gap between the two outcomes is $19 a paycheck if you are under 50 or in the 60 to 63 group, and $38 if you use the regular age-50 catch-up.

The TSP Contribution Calculator lets you test a per-paycheck amount against the 2026 limit and your agency match. It does not carry 2027 limits yet.

Aim High: Why $981 Is the Safer Election

If you are a FERS employee under 50 who maxes out, you can set your election before the IRS announces.

TSP rejects only the part of a contribution that goes over the limit. So if you elect $981 and the limit turns out to be $25,000:

• After 25 paydays you have contributed $24,525.
• Your 26th paycheck contributes the remaining $475.
• That $475 still earns the full match as long as it is at least 5% of your basic pay for the period. That holds if your biweekly basic pay is $9,500 or less, about $247,000 a year.

Elect $962 and guess low, and you leave $488 of room unused unless you raise the election before the year ends.

That last paycheck matters because of how matching works. Under 5 U.S.C. § 8432, the agency match is figured on what you contribute in each pay period. TSP's own guidance says FERS and BRS participants "who reach the limit before the final pay date of the year will also miss out on matching contributions for the rest of the year."

If you are 50 or older, contributions past the regular limit spill over into catch-up automatically, and TSP says spillover contributions "will be matched, but only on up to the 5% of salary to which participants are already entitled." The match stops once you reach both limits. For BRS members, TSP says matching also stops at the total additions cap even if catch-up room remains.

Catch-Up Contributions and the Roth Rule in 2027

Ages 60 to 63. This higher catch-up started at $11,250 and is now indexed on its own schedule. It is projected to rise $500 to $11,750 for 2027.

The Roth requirement. If your prior-year Social Security wages from federal employment (Box 3 of your W-2) were over the IRS threshold, your catch-up contributions have to be Roth. For most participants TSP applies this automatically: once your traditional contributions reach the regular limit, payroll switches the excess to Roth. TSP tells everyone else to check with their payroll office that catch-up contributions will be designated Roth.

Two things change for 2027:

• The test uses your 2026 wages against a threshold the IRS will publish this fall. We project $155,000. The $150,000 figure in use this year applied to 2025 wages.
• 2027 is the first year the IRS's final regulations on the Roth catch-up rule generally apply.

CSRS employees with no Social Security wages are not subject to the Roth catch-up rule. TSP's explanation is that Box 3 of their W-2 is zero. CSRS Offset employees pay Social Security tax, so they should check their prior-year Box 3 wages.

Guard and Reserve members with a civilian account. You get one regular limit across both TSP accounts, not two.

Combat-zone pay. Traditional contributions from tax-exempt pay do not count toward the regular limit, but they do count toward the total additions cap, $72,000 in 2026 and projected at $75,000 for 2027. For service members with tax-exempt combat-zone pay, contributions toward the catch-up limit can only be Roth.

Contributions count toward the year your paycheck is dated, so the election that governs your first January paycheck has to be in place in December. Under 5 C.F.R. § 1600.12, a new election takes effect no later than the first full pay period after your agency receives it.

For this year's rules, see our 2026 TSP limits guide. For the 2027 payday schedules, see the federal pay period calendar and the GSA payroll calendar.

Frequently Asked Questions

What will the 2027 TSP contribution limit be?

It is projected at $25,500, with $25,000 as the fallback. The tax code indexes a $15,000 base to inflation and rounds down to the nearest $500. By FedTools' calculation, the 2027 limit is $25,500 if September 2026 CPI-U reaches about 335.12 and $25,000 if it does not. It is not official until the IRS publishes its notice.

When will the 2027 TSP limit be official?

BLS releases the September CPI on October 14, 2026, which makes the number computable. The IRS announcement comes later. In the last three years it came on November 1, 2023, November 1, 2024 and November 13, 2025.

How much should I contribute per paycheck to max out in 2027?

Over 26 paydays, elect $962 per paycheck to reach $25,000 or $981 to reach $25,500. If you also max the regular age-50 catch-up, the figures are $1,270 or $1,308. In the year you turn 60 through 63, they are $1,414 or $1,433. These are FedTools calculations on projected limits.

What happens if I elect $981 and the limit is $25,000?

Payroll stops you at the limit. After 25 paydays you would have contributed $24,525, and your final 2027 paycheck would contribute $475. For a FERS employee under 50, that still earns the full agency match unless basic pay is above about $247,000 a year.

What will the TSP catch-up limits be in 2027?

The age-50 catch-up is projected at $8,500 if the regular limit reaches $25,500, and $8,000 otherwise. The ages 60 to 63 catch-up is projected at $11,750, up from $11,250 in 2026. Neither is confirmed.

Does maxing out my TSP early cost me the agency match?

If you are under 50, yes. TSP says FERS and BRS participants who reach the limit before the final pay date of the year miss matching contributions for the rest of the year. If you are 50 or older, contributions spill over into catch-up and keep earning the match on up to 5% of salary until you reach both limits. For BRS members, matching also stops at the total additions cap.

Does the Roth catch-up rule change in 2027?

The wage test changes. For 2027, your 2026 Social Security wages (Box 3 of your W-2) are tested against a threshold the IRS will publish this fall, which we project at $155,000. 2027 is also the first year the IRS's final regulations on the rule generally apply.

I am in the Guard or Reserve and also a federal civilian. Do I get two limits?

No. Your employee contributions to a civilian TSP account and a uniformed services TSP account share one regular limit.

When do I need to change my TSP election for 2027?

Early December 2026. A new election takes effect no later than the first full pay period after your agency receives it, and NFC's first 2027 payday, January 7, pays a pay period that begins December 13, 2026.

Related Resources

• TSP Limits 2026: This year's limits and how the catch-up rules work.
• TSP Calculator: Project your balance at different contribution rates.
• 27 Pay Periods in 2026: Why some payroll calendars had an extra payday this year.

Sources

• IRS: 401(k) limit increases to $24,500 for 2026 (Notice 2025-67)
• 26 U.S.C. § 402 and 26 U.S.C. § 415: indexing rules
• BLS CPI release schedule and BLS CPI-U series CUUR0000SA0
• TSP contribution limits and TSP Bulletins 25-3, 23-5 and 20-1
• 5 U.S.C. § 8432: agency contributions
• 5 C.F.R. part 1600: contribution elections
• IRS: final regulations on the Roth catch-up rule
• Milliman and Mercer 2027 limit projections, September 2026