Roth TSP vs Traditional TSP: Which Is Better for Feds?

By the OnPAR Federal Retirement Education editorial team · Last updated November 9, 2026

Related: TSP guides · TSP limits and Roth catch-up · TSP withdrawal options · Pension and TSP taxes in 2026

Short answer: With traditional TSP you skip tax now and pay it when you withdraw. With Roth you pay tax now and qualified withdrawals are tax-free [1]. Neither is better for everyone. The key question is whether your tax rate will be higher or lower in retirement than it is today. In 2026 you can put in up to $24,500 (traditional and Roth combined), plus catch-up if you are 50 or older [2]. Your agency’s automatic and matching contributions always go to your traditional balance [4] [1]. This page is education, not advice.

1. The basic difference

“Qualified” Roth earnings need both: 5 years since January 1 of the year of your first Roth contribution, and you are 59½ or older, disabled or deceased [1] [7]. If you start your Roth balance with an in-plan conversion, that conversion counts as your first Roth contribution [5].

2. 2026 limits and the new Roth catch-up rule

New in 2026: if you earned more than $150,000 in 2025, any catch-up contributions you make this year must be Roth, regardless of your election [3]. For people over that threshold, once traditional contributions reach $24,500, further contributions count as catch-up and go to Roth [3]. The 2027 limits have not been announced by the IRS yet; see TSP limits 2027 and Roth catch-up.

3. Example: the same $10,000, three retirement tax rates

Assume you set aside $10,000 of pay while in the 22% federal bracket (single filers: $50,400 to $105,700 of taxable income in 2026) [9]. To keep the comparison fair, assume the money doubles by retirement. (A doubling is an illustration only, not a forecast.) Traditional: all $10,000 is invested. Roth: you pay 22% tax first, so $7,800 is invested. The math:

The rule of thumb: traditional wins if your rate falls, Roth wins if it rises, and it is a tie if it stays the same. The TSP says Roth “may be a smart choice if you expect to be in a higher tax bracket when you need to withdraw” [1]. Real life adds wrinkles: your pension, Social Security and RMDs can push your retirement income up, and tax laws change.

4. Things that can tip the decision

• Your FERS pension and Social Security stack on top of TSP withdrawals. Traditional withdrawals add to taxable income and can make more Social Security taxable; qualified Roth withdrawals don’t [4]. See is Social Security taxable with a pension.
• Flexibility: a mix gives you both taxable and tax-free money to draw from.
• Early withdrawals: the 10% early-withdrawal penalty has an exception if you separate in or after the year you turn 55 [4].
• Heirs: Roth balances don’t have RMDs during your life [6], and qualified Roth money is tax-free to beneficiaries if the 5-year condition is met [5].
• Agency match: contribute at least 5% to get the full match either way (1% automatic, plus a dollar-for-dollar match on the first 3% and 50 cents on the next 2%). See the TSP guides.

5. Already have traditional money? Roth in-plan conversions

Since January 28, 2026 you can convert money from your traditional balance to Roth inside the TSP, working or retired [7] [8]. What the TSP says [7] [8]:

• The converted amount is taxable income that year, and it could push you into a higher bracket.
• The TSP cannot withhold tax on a conversion. You must pay the tax from other money, not from the amount you convert.
• The minimum is $500. A conversion is irreversible. Up to 26 conversions per account per year.
• If you must take an RMD, you have to take it before converting; conversion can’t satisfy it.
• Each conversion starts its own 5-year clock for the 10% early-withdrawal penalty on converted money if you take it out before 59½ [7].

The TSP strongly recommends talking to a tax advisor before converting [8]. Compare it with withdrawing and rolling to an IRA in TSP withdrawal options.

What to do next

1. Log in to the TSP and check your current election (traditional, Roth or a split).
2. Estimate your tax bracket now and a rough retirement bracket using your pension estimate (pension calculator) and the TSP withdrawal calculator.
3. Make sure you are getting the full 5% match.
4. If you earned over $150,000 in 2025 and contribute past $24,500, confirm with your payroll office that catch-up goes to Roth [3].
5. Learn how TSP money is taxed when you take it: pension and TSP taxes in 2026. Next: the TSP fund guide.

Questions and answers

Should I choose Roth or traditional TSP?

There is no single right answer. Traditional lowers your tax now and is taxed when withdrawn. Roth is taxed now and qualified withdrawals are tax-free. Roth tends to favor people who expect a higher tax rate in retirement; traditional tends to favor those expecting a lower one. Many people split.

Does the agency match go into my Roth TSP?

No. Agency automatic (1%) and matching contributions always go to your traditional balance, even if all of your own contributions are Roth.

What is the 2026 TSP contribution limit?

$24,500 for traditional and Roth combined, plus an $8,000 catch-up if you are 50 or older ($11,250 if you turn 60 to 63 in 2026). If you earned more than $150,000 in 2025, your catch-up contributions must be Roth.

Can I convert my traditional TSP to Roth?

Yes. Since January 28, 2026 the TSP offers Roth in-plan conversions in My Account. The conversion is taxable income that year, the tax must be paid from other money, the minimum is $500, and it cannot be reversed.

Official sources

1. TSP: Roth and traditional, what is the difference (taxes)
2. TSP Bulletin 25-3: 2026 TSP contribution limits
3. TSP: Contribution types (what is new in 2026, Roth catch-up rule)
4. IRS Publication 721: Tax Guide to U.S. Civil Service Retirement Benefits
5. TSP booklet: Payments from the TSP (taxes and Roth rules, PDF)
6. TSP: SECURE 2.0 and the TSP (Roth balances and RMDs)
7. TSP: Roth in-plan conversions
8. TSP Bulletin 25-4: Launch of Roth in-plan conversions
9. IRS: 2026 tax inflation adjustments (brackets and standard deduction)

Checked against IRS, OPM, SSA and TSP sources on November 6, 2026. Education only, not legal, tax or financial advice. Your own situation may differ: check with a tax professional, OPM, the TSP or your state tax office. Not affiliated with OPM, the IRS, SSA, the TSP or any government agency.