Roth TSP vs. Traditional TSP: Which Should You Choose

September 16, 2026 · Joe, Wealthy Warriorz

The core difference is when you pay taxes, not whether you pay them.

The difference in one example

The TSP's own example makes it simple. Say you're in a 20% tax bracket and you put $1,000 into your TSP.

Traditional: the $1,000 comes out before taxes, so your taxable income drops by $1,000 and you keep $200 more in your paycheck this year. In retirement, you pay tax on that money and everything it earned. Pull out $1,000 at 20% and you keep $800.
Roth: the $1,000 comes out after taxes, so your paycheck doesn't change. In retirement, you get the whole $1,000, plus what it earned, tax-free.

So the real question is whether your tax rate will be higher now or later.

Traditional TSP

Traditional TSP takes contributions before tax, lowering your taxable income now, and taxes the withdrawals in retirement. This tends to favor people who expect to be in a lower tax bracket later than they are now: senior people in high brackets today, or anyone who expects to live on a lot less in retirement.

Roth TSP

Roth TSP takes contributions after tax, so there's no deduction now, but qualified withdrawals in retirement are entirely tax-free, growth included. This tends to favor people who expect their tax bracket to be the same or higher later, which describes a lot of junior service members early in their careers.

"Qualified" has two conditions. It has to be at least 5 years since January 1 of the year you made your first Roth contribution, and you have to be at least 59½ (or disabled). Your own contributions always come out tax-free. It's the growth that needs both conditions. That's one more reason to start a Roth balance early, even a small one: it starts the 5-year clock.

Roth money also has no required minimum distributions, so you can leave it in the TSP and let it keep growing as long as you want.

Why Roth fits a lot of junior service members

Your housing and food allowances (BAH and BAS) aren't taxed. So your taxable income is mostly your base pay, which puts a lot of junior enlisted and junior officers in a low bracket. Paying tax now, at a low rate, and never paying it again on decades of growth is hard to beat.

The TSP suggests asking yourself a few questions. If you answer yes, Roth likely makes more sense:

Are you in a very low tax bracket right now?
Will you keep working, full-time or part-time, after you start taking TSP money?
Will you have other taxable income in retirement, like a pension, a civilian job, or Social Security?

If you answer yes to these instead, traditional may be the better fit:

Are you in a high tax bracket right now?
Will you need a lot less money in retirement than you earn today?

Your match always goes into traditional

Under the Blended Retirement System, the service's 1% automatic contribution and its matching contributions always go into your traditional balance, no matter what you pick. Your Roth contributions still get matched. So even if you put 100% of your own money into Roth, you'll have both balances, and part of your retirement will be taxed when you take it out either way.

Deployed? The math changes

Pay you earn in a combat zone is tax-exempt, and that changes the choice:

Roth from tax-exempt pay may never be taxed. It isn't taxed going in, and the contributions and qualified growth aren't taxed coming out. That's about as good as a tax break gets.
Traditional from tax-exempt pay is also never taxed on the contributions, but the growth is taxed when you take it out.

One catch: tax-exempt Roth contributions count toward the $24,500 yearly limit, and tax-exempt traditional contributions don't. If you hit the limit before the year is out, your contributions stop, and so does your match for the rest of the year. If you're putting in a lot while deployed, watch the math so you don't lose match money.

A middle path

A middle path exists too: splitting contributions between both, so you're covered whichever way tax rates go. You can also change your split whenever you want. Revisit it when you promote, separate, get married, or deploy.

I personally lean heavily toward the Roth option in my own TSP, on the bet that tax rates and my own income are both more likely to be higher later than they are right now. That's a personal bet based on my own situation, not a universal rule.

New in 2026: converting traditional to Roth

Since January 2026, you can move money from your traditional TSP balance into your Roth balance. It's called a Roth in-plan conversion. The amount you convert counts as taxable income that year, and you have to pay that tax with money from outside the TSP, like savings. The TSP recommends talking to a tax advisor first. It can make the most sense in a year when your income is low.

The 2026 limits

$24,500 for your own contributions, traditional and Roth combined.
$8,000 extra in catch-up contributions if you're 50 or older ($11,250 if you're 60 to 63).
The match doesn't count toward the $24,500.
A Roth IRA outside the TSP has its own separate limit, so you can do both.

Your checklist

Make sure you're putting in at least 5% to get the full match.
Look at your last tax return and find your bracket.
Answer the TSP's questions above, and pick Roth, traditional, or a split.
If you deploy, decide how to handle tax-exempt pay before you go. The rest of the list is in Before You Deploy: The Money Checklist I Wish I'd Had.
Revisit your choice every time your pay or your plans change.

Whichever you choose, prioritize contributing enough to get the full government match first. The Roth-versus-Traditional decision matters less than the decision to actually contribute in the first place. If market swings are what's keeping you out, read Market Fear and Your TSP. If the money to contribute isn't there yet, 10 Things to Stop Buying If You Want to Retire Early is a good place to find it.

Sources: TSP, Traditional and Roth TSP contributions; TSP, 2026 contribution limits; IRS Publication 3, Armed Forces' Tax Guide; checked September 2026.

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Disclaimer: I am not a financial advisor. The information provided here is for educational purposes only and should be verified independently. See the full Disclaimer.