2027 TSP contribution limits: the projection, the per-pay-period math, and the December election

1. The 2027 table: final and projected

The projections are Milliman’s, the actuarial forecast most plan sponsors use. Its March forecast projected $25,000; every monthly update since April, including the August 13 forecast built on the July CPI, projects $25,500. Both are shown in section 3 so that whichever the IRS confirms, the per-period figure is already on the page.

2. How the limits are indexed

Under Internal Revenue Code section 402(g), the elective deferral limit is indexed to the CPI-U using the twelve months ending September 30 and adjusted in $500 increments: the limit rises to the next $500 step only once cumulative inflation since the last increase justifies it. That is why the limit sometimes rises $500 and sometimes $1,000 ($23,500 to $24,500 for 2026), and occasionally not at all. With twelve-month CPI-U running at 3.4% through July, the unrounded 2027 figure sits close to the $25,500 threshold, which is why the projection moved from $25,000 to $25,500 in April and has held there. The August CPI on September 11 and the September CPI on October 14 decide it.

The regular catch-up is indexed the same way in $500 steps but from a lower base, so it moves less often; it rose to $8,000 for 2026 and is not projected to move for 2027. The super catch-up under SECURE 2.0 is the greater of $10,000 or 150% of the 2024 regular catch-up, indexed separately from 2026, which is how it can rise $500 while the regular catch-up stays flat. The Roth catch-up wage threshold started at $145,000 and is indexed; it is $150,000 for 2026.

3. Per-pay-period amounts for every scenario

Rounding up by a dollar means the final pay period’s contribution is a few dollars short of the full amount; payroll systems stop at the limit automatically, and the match in that period is unaffected because you still contributed at least 5%. Rounding down leaves a few dollars of limit unused; either is fine. What is not fine is a figure so large that the limit is reached in pay period 20, which is section 4.

The super catch-up applies in the calendar year you turn 60, 61, 62, or 63 and reverts to the regular catch-up in the year you turn 64. Age at year-end governs: an employee who turns 60 on December 30, 2027 can use the super catch-up for all of 2027. See the super catch-up guide.

4. The match, and why the per-period figure matters

FERS employees receive an automatic 1% agency contribution plus a match of up to 4%: dollar for dollar on the first 3% of basic pay contributed each pay period, fifty cents on the dollar for the next 2%. The match is computed per pay period and paid only for periods in which you contribute. Reach the annual limit in October and you contribute nothing in November and December, so the agency contributes nothing but the automatic 1% in those periods. On a $150,000 salary, six missed pay periods cost about $1,385 of match; on the GS-15 cap, closer to $1,800. The annual leave lump sum, a large final check for retirees, is not basic pay and earns no match. The per-pay-period figure exists to prevent exactly this, and the front-loading trap is the most common way federal employees lose free money.

5. The mandatory Roth catch-up

Since January 2026, employees whose FICA wages from their employer in the prior calendar year exceeded the indexed threshold ($150,000 of 2025 wages for 2026) must make every catch-up contribution, regular or super, to the Roth TSP. Regular contributions up to the deferral limit can still be traditional. The threshold for 2027 will be published with the other limits and is expected to be roughly $150,000 to $155,000 of 2026 wages. The rule is applied by payroll based on the prior year’s W-2 Social Security wages; you do not elect it and cannot decline it.

For a GS-14 or GS-15 in a high-locality area, the practical effect is that $8,000 to $11,750 of contributions that were deductible in 2025 are now after-tax, at the top marginal rate, in exchange for a Roth balance that is never taxed again and, since 2024, never subject to RMDs. That is not a bad trade for anyone who expects to be in a comparable bracket in retirement, and it starts the Roth TSP five-year clock for anyone who has never had Roth money. Plan for the higher withholding in the first 2027 paycheck.

6. The December election, step by step

• Early November: the IRS publishes the 2027 limits. This page is updated the same day with the final per-period figures.
• Compute: limit ÷ 26, rounded up. Add the catch-up if you will be 50 or older at any point in 2027 (age at December 31 governs), or the super catch-up if you will be 60 to 63 at December 31, 2027.
• Check the Roth rule: if your 2026 W-2 Social Security wages will exceed the threshold, direct the catch-up to Roth. Regular contributions are your choice.
• Enter the election in the pay period ending in mid-December 2026, through your agency’s system (Employee Express, MyPay, EPP, or equivalent), as a dollar amount. Elections take effect in the pay period after they are made; the first full 2027 pay period begins January 10, 2027 for most agencies. Made too early, the new amount applies to a 2026 paycheck and can push you over the 2026 limit; made too late, the first 2027 period runs at the old amount and you have 25 periods to catch up.
• Verify on the first 2027 LES. Confirm the deduction, the traditional/Roth split, and the agency match at the full 5%.

7. Special cases: retiring in 2027, 27 pay periods, uniformed services

Retiring during 2027. Contributions stop with your final salary payment. Divide the amount you intend to contribute by the pay periods you will actually be paid, not 26, so the match is captured in each of them. A June 30 retiree with 13 paid periods contributes $1,962 per period to reach a $25,500 limit; whether that is worth doing depends on cash flow, but the match is worth capturing in every period you work. The final-years guide covers the rest of the retirement-year TSP sequence.

27-pay-period years. Some agencies’ 2027 calendars have 27 pay dates because of how the biweekly cycle falls. The limit applies to the calendar year in which the contribution is paid. If your agency shows 27 paydays in 2027, divide by 27, or accept that the 27th contribution will be blocked by the limit and the match in that period lost. Check your agency’s payroll calendar in December.

Uniformed services and civilian accounts. The elective deferral limit is a single limit across both accounts; contributions to a uniformed services TSP count toward the same $25,500. Tax-exempt combat-zone contributions to traditional TSP are excluded from the deferral limit but count toward the annual additions limit.

Over the limit. Payroll stops contributions at the limit automatically; the TSP refunds any excess deferral it identifies from a second plan by April 15. The failure mode is not over-contributing, it is under-matching.

8. Update log

9. Frequently asked questions