Traditional or Roth 401(k): how to choose

A traditional and a Roth 401(k) hold the same investments and share the same contribution limit. They differ on one thing: when you pay the tax. A traditional 401(k) skips the tax on the money going in this year and taxes it on the way out in retirement. A Roth 401(k) takes after-tax money now and never taxes it again, including all the growth. So the whole decision comes down to a single question. Is your tax rate higher today or higher in retirement? Pay the tax in the year your rate is lower, and you keep more.

The two accounts, side by side

Both are workplace retirement plans. You pick a percentage of your paycheck, it gets invested in funds your plan offers, and it compounds for decades. The fork is purely about taxes.

With a traditional 401(k), your contribution comes out before income tax is calculated, so it lowers your taxable income this year. Put in $10,000 and you do not pay tax on that $10,000 now. The catch arrives in retirement: every dollar you withdraw, the original contribution plus all the gains, counts as ordinary income and gets taxed at whatever your rate is then.

With a Roth 401(k), you contribute money that has already been taxed, so it does nothing for your tax bill this year. The payoff comes later. Qualified withdrawals in retirement are completely tax-free. The contributions, the decades of growth, all of it comes out with zero tax owed.

The 2025 limits apply to both

For 2025, the employee contribution limit is $23,500, and it is shared across both flavors. You can put $23,500 into traditional, $23,500 into Roth, or any split that adds up to $23,500. It is one ceiling, not two. If you are 50 or older, a catch-up provision lets you add more on top, but for a young saver the number to know is $23,500.

The employer match sits outside that $23,500 employee limit. If your company matches, take the full match before you fine-tune the traditional-versus-Roth question. A match is an instant return that no tax treatment can beat. We walk through why in our piece on the 401(k) match.

The deciding question: your bracket now vs later

Strip away the jargon and you are betting on one comparison. If you expect a lower tax rate in retirement than you pay today, the traditional account wins, because you dodge a high rate now and pay a low rate later. If you expect a higherrate in retirement, the Roth wins, because you lock in today's low rate and skip the higher one later.

That is the entire framework. Everything else is just figuring out which side of that line you are on. To see how brackets stack and where your income falls, run your numbers through our tax bracket calculator, and read the taxes guide if the bracket math is new to you.

A worked example: $10,000 at two different rates

Say you contribute $10,000 in a year when your top federal rate is the 22% bracket, and you expect to be in the 12% bracket when you withdraw it in retirement. To make the comparison fair, assume the money grows the same in both accounts and you have the same total to invest. The only thing that changes is when the tax bites.

With the traditional account, you defer the 22% bill and eventually pay 12% instead. On a $10,000 contribution that grows to, say, $40,000 over a few decades, the traditional withdrawal gets taxed at 12%, which is $4,800. The Roth saver already handed over $2,200 up front to shelter the same $10,000. But here the deal favors traditional, because paying 12% later beats paying 22% now. When your retirement rate is lower than your working rate, traditional wins.

Flip the brackets and the answer flips with them. Suppose you are early in your career in the 12% bracket today, and you reasonably expect to be in the 22% bracket by retirement after a career of raises. Now the Roth is the better move. You pay 12% on the $10,000 now ($1,200), and that money plus all its growth comes out tax-free later, dodging the 22% rate entirely. Same accounts, opposite decision, because the bracket comparison reversed.

Where young earners usually land

Most people in their twenties and early career are in a low bracket today and have decades of income growth ahead. Their rate now is about as low as it will ever be, which tilts the math toward Roth. Paying a 12% tax bill on a contribution that grows tax-free for 40 years is a strong deal, and it is the same logic behind starting a Roth IRA at 22.

High earners today often go the other way. If you are in the 32% or 35% bracket, deferring tax now with a traditional 401(k) is valuable, because very few retirees pay 32% on their withdrawals. The traditional deduction is worth more the higher your current rate, which is exactly why it appeals to people at the top of the income range.

Nobody knows future tax rates or where their own income will land, so this is a forecast, not a certainty. That uncertainty is the honest case for splitting your contributions, which we cover in the FAQ below.

FAQ

Which should a 25-year-old pick?

For most 25-year-olds, the Roth 401(k) is the stronger default. At that age you are usually in a low bracket, your income has decades of room to rise, and the tax-free growth has the longest runway to work. Paying a modest tax now to make 40 years of compounding tax-free is a good trade. The exception is if you are already a high earner in your mid-twenties, sitting in the 32% bracket or above. Then the traditional deduction is worth enough today that deferring the tax makes sense. Check your bracket before you assume.

Can I split between both?

Yes, and many people do. You can send part of your contribution to traditional and part to Roth, as long as the combined total stays within the $23,500 employee limit for 2025. Splitting is a hedge against not knowing future tax rates: you get a deduction now from the traditional side and a tax-free bucket from the Roth side. A 50/50 split is a common, defensible choice when you genuinely cannot tell which way your bracket will move.

Does the match change the decision?

No. The match goes in pre-tax no matter which option you pick, so it is the same either way and does not tip the traditional-versus-Roth choice. What the match should change is your priority order: contribute enough to capture the full match first, then decide how to split the rest between traditional and Roth. A Roth saver simply ends up with a tax-free bucket from their own contributions and a separate pre-tax bucket from the employer match.

What if my plan does not offer a Roth 401(k)?

Plenty of plans only offer the traditional version, and that is fine. Use it to get the full match and a solid pre-tax contribution. If you want tax-free growth on top, open a Roth IRA on your own. It carries a separate contribution limit and the same tax-free treatment, so you can build a Roth bucket even when your workplace plan has only the traditional door.