You're filling out your company's benefits paperwork and hit a fork in the road: traditional 401(k) or Roth 401(k). Both boxes promise to help you retire someday. Only one of them lets your money grow completely tax-free.
A Roth 401(k) is a retirement account offered through your employer that works like a regular 401(k), except you pay taxes on your contributions now instead of later. In exchange, every dollar of growth — decades of it, potentially — comes out tax-free in retirement.
By the end of this article, you'll know exactly how a Roth 401(k) works, how it compares to a traditional 401(k), and how to figure out which one makes sense for your income and your age.
What Is a Roth 401(k)?
A Roth 401(k) is an employer-sponsored retirement plan that combines the contribution limits of a 401(k) with the tax treatment of a Roth IRA. You contribute money you've already paid income tax on. Your investments grow inside the account, and when you withdraw the money in retirement, you owe nothing — not on your contributions, and not on the growth.
That's the entire trade. Pay tax today, skip it later.
Many employers now offer a Roth 401(k) option alongside the traditional one. Some let you split contributions between both — say, half your paycheck deduction going Roth, half going traditional. You can also still get an employer match with a Roth 401(k), though by law, employer matching dollars go into a traditional (pre-tax) account, not the Roth one.
For 2025, you can contribute up to $23,500 to a Roth 401(k) if you're under 50, according to the IRS. If you're 50 or older, you can add a $7,500 catch-up contribution, bringing your total to $31,000. If you're between 60 and 63, a special catch-up rule under SECURE 2.0 lets you contribute up to $34,750.
Roth 401(k) vs. Traditional 401(k): What's the Difference?
The difference comes down to when you pay taxes, not how much you pay overall.
| Feature | Roth 401(k) | Traditional 401(k) |
|---|---|---|
| When you pay tax | Now, on contributions | Later, on withdrawals |
| Contribution limit (2025) | $23,500 (+ catch-up) | $23,500 (+ catch-up) |
| Growth | Tax-free | Tax-deferred |
| Withdrawals in retirement | Tax-free (if qualified) | Taxed as ordinary income |
| Required minimum distributions | None, as of 2024 | Start at age 73 |
| Income limits to contribute | None | None |
One detail catches people off guard: unlike a Roth IRA, a Roth 401(k) has no income limit. High earners who are shut out of a Roth IRA can still fully fund a Roth 401(k) through their workplace plan.
Another recent change worth knowing — as of 2024, Roth 401(k)s no longer require you to take required minimum distributions (RMDs) during your lifetime, thanks to SECURE 2.0. That puts them on equal footing with Roth IRAs for estate planning purposes.
Who Should Use a Roth 401(k)?
The simplest way to decide is to compare your tax rate now with your expected tax rate in retirement.
A Roth 401(k) tends to make sense if:
- You're early in your career and in a lower tax bracket than you expect to be later
- You think tax rates will be higher in the future, either for you personally or across the board
- You want tax-free income in retirement to avoid pushing yourself into a higher bracket
- You've already maxed out a traditional 401(k) or IRA and want more tax diversification
A traditional 401(k) tends to make more sense if:
- You're in your peak earning years and in a high tax bracket right now
- You expect your income — and tax rate — to drop significantly in retirement
- You want to lower your taxable income today
Here's a concrete example. Say you're 30 years old, earning $70,000 a year, and you contribute $10,000 to a Roth 401(k). You pay tax on that $10,000 now, at your current rate. If that money grows to $80,000 by retirement, you owe nothing on the $70,000 of growth.
Compare that to a traditional 401(k): you skip tax on the $10,000 today, but you'll owe income tax on the full $80,000 when you withdraw it in retirement — growth included.
If your tax rate stays roughly the same from now until retirement, the math works out about the same either way. The Roth account wins if your rate is lower now than it will be later. The traditional account wins if the opposite is true.
A Simple Way to Split the Difference
You don't have to pick just one. Many people split contributions between a Roth 401(k) and a traditional 401(k) to hedge against uncertainty about future tax rates.
A common approach: contribute enough to your traditional 401(k) to get your full employer match, then direct any additional savings to the Roth option. This gets you an immediate tax break on the match dollars while building a pool of tax-free money for later.
To see how either choice affects your long-term retirement balance, run your numbers through the retirement calculator. Plugging in your age, income, and contribution rate shows you how much your account could grow by retirement — and helps you compare Roth versus traditional scenarios side by side.
Frequently Asked Questions
Is a Roth 401(k) better than a traditional 401(k)? Neither is universally better. A Roth 401(k) is typically better if you expect to be in a higher tax bracket in retirement than you are now. A traditional 401(k) is typically better if you expect a lower tax bracket later.
Can I contribute to both a Roth 401(k) and a traditional 401(k)? Yes. Many plans let you split contributions between both, as long as your combined total stays within the annual IRS limit — $23,500 for 2025, plus any catch-up contributions you qualify for.
Does my employer match go into the Roth account? No. Employer matching contributions are always deposited into a traditional, pre-tax account, even if your own contributions go into the Roth 401(k). You'll owe tax on the match — and its growth — when you withdraw it.
Is there an income limit for a Roth 401(k)? No. Unlike a Roth IRA, which phases out for higher earners, a Roth 401(k) has no income restrictions. Anyone with access to the plan through their employer can contribute, regardless of salary.
Can I roll a Roth 401(k) into a Roth IRA? Yes. When you leave your job or retire, you can roll your Roth 401(k) balance into a Roth IRA without triggering taxes, as long as it's a direct rollover. This can also help you avoid future RMDs and simplify your accounts.
The Bottom Line
A Roth 401(k) lets you pay taxes now so your money can grow — and come out — completely tax-free later. It tends to work best for people who expect their tax rate to rise over time, while a traditional 401(k) often suits people expecting a lower rate in retirement. Use the retirement calculator to model both options with your real numbers and see which one leaves you better off.
This article is for informational purposes only and does not constitute financial advice. Always consult a qualified financial advisor before making major financial decisions.