Traditional vs Roth 401(k): What's the Difference?

The main difference between a traditional and Roth 401(k) is when you pay income tax. With a traditional 401(k), you put in pre-tax dollars, lowering your taxable income now, but you pay ordinary income tax on every dollar you withdraw in retirement. With a Roth 401(k), you contribute after-tax dollars, so there's no upfront tax break, but qualified withdrawals, including investment earnings, are completely tax-free. Both account types share the same annual contribution limit, and many employer plans offer both options.

What is a traditional 401(k)?

A traditional 401(k) is an employer-sponsored retirement account where your contributions come out of your paycheck before income taxes are calculated. For example, if you earn $60,000 and contribute $5,000 to a traditional 401(k), your taxable income for the year drops to $55,000. The money then grows tax-deferred, meaning you don't pay taxes on dividends, interest, or capital gains while it stays in the account. When you withdraw money in retirement, those withdrawals are taxed as ordinary income at whatever tax rate applies to you that year.

Most employers that offer a 401(k) also provide a matching contribution, such as 50 cents for every dollar you put in up to a certain percentage of your salary. Employer matches are always made with pre-tax dollars, even if you contribute to a Roth account. That means the match itself grows tax-deferred, and you'll pay taxes on it when you take it out.

For more on how your money can grow over time, see our guide on how compound interest works.

What is a Roth 401(k)?

A Roth 401(k) is also an employer-sponsored retirement account, but contributions are made with after-tax dollars. Your paycheck contribution is taxed first, then deposited into the account. You get no immediate tax deduction, but the payoff comes later: if you meet the rules for a qualified distribution, both your original contributions and all the investment earnings come out tax-free. A qualified distribution generally requires that you are at least age 59½ and that the account has been open for at least five years.

Roth 401(k)s have been around since 2006, and they've become common. According to a 2026 survey by the Transamerica Institute, 72% of plan sponsors offer a Roth option. Unlike a Roth IRA, there are no income limits for contributing to a Roth 401(k), so high earners can use it even if they can't contribute to a Roth IRA directly.

One important detail: if your employer matches your Roth contributions, that match goes into a separate pre-tax account. You'll owe taxes on the match and its earnings when you withdraw them.

Key differences at a glance

The table below summarizes the main differences between traditional and Roth 401(k) plans.

Both types share the same annual contribution limit. For 2026, the IRS sets the employee contribution limit at about $24,500, with an additional $8,000 catch-up for those aged 50 and older, as detailed on the IRS 401(k) contribution limits page. If you split your contributions between a traditional and Roth 401(k), the combined total can't exceed this limit.

How taxes work: a step-by-step example

Let's compare two people, Alex and Jordan, who each earn $70,000 per year and each contribute $10,000 to their employer's 401(k). Alex chooses the traditional option; Jordan chooses the Roth option. Assume both are single and take the standard deduction. For simplicity, we'll use a flat 22% tax rate on taxable income above the standard deduction, ignoring other deductions and credits.

For 2026, the standard deduction for a single filer is about $15,000 (see the IRS tax inflation adjustments).

Alex (traditional): His taxable income is $70,000 - $10,000 (401(k) contribution) - $15,000 (standard deduction) = $45,000. The tax on $45,000 at a flat 22% is $9,900. So Alex pays $9,900 in federal income tax for the year.

Jordan (Roth): Jordan gets no deduction for the $10,000 contribution, so his taxable income is $70,000 - $15,000 = $55,000. At 22%, his tax is $12,100. That's $2,200 more than Alex pays in the current year.

Now let's fast-forward 30 years. Assume both accounts grow at an average annual return of 7%. Using the future value formula, $10,000 per year for 30 years at 7% grows to about $944,608 (calculated as $10,000 × [(1.07^30 - 1) / 0.07]).

In retirement, both Alex and Jordan decide to withdraw $40,000 per year from their 401(k)s. Alex's withdrawals are fully taxable as ordinary income. If his only income is that $40,000, after the standard deduction his taxable income is $25,000. At a 22% flat rate, he owes $5,500 in tax, leaving him $34,500 after tax. Jordan's Roth withdrawals are tax-free, so he keeps the full $40,000.

The table below shows the yearly after-tax withdrawal for each.

In this scenario, Jordan ends up with more spendable income in retirement, but he paid more tax during his working years. If Alex's retirement tax rate were lower than 22%, the traditional account could come out ahead. The key is comparing your marginal tax rate now versus your effective tax rate in retirement.

What people get wrong about traditional vs. Roth 401(k)

Mistake 1: Thinking your tax bracket in retirement is the same as your tax bracket now

Many people assume that if they're in the 22% bracket now, they'll be in the 22% bracket in retirement. But retirement income often comes from multiple sources, and your withdrawals fill tax brackets from the bottom up. For example, a married couple withdrawing $80,000 from a traditional 401(k) in 2026 would pay a total tax of about $8,400 after the standard deduction, which is an effective rate of about 10.5%, not 22%. Your marginal rate at contribution is what you save, but your effective rate on withdrawals is what you pay. That difference can make the traditional account more attractive than many people think.

Mistake 2: Believing Roth 401(k) withdrawals are always tax-free

Roth 401(k) withdrawals are only tax-free if they are qualified distributions. That means you must be at least 59½ and the account must have been open for at least five years. If you withdraw earnings early, you may owe income tax plus a 10% penalty on the earnings portion. Also, if your employer match is in a pre-tax sub-account, withdrawals from that sub-account are taxable, even if your own contributions were Roth.

Mistake 3: Ignoring required minimum distributions (RMDs) for traditional 401(k)s

Traditional 401(k)s require you to start taking required minimum distributions (RMDs) at age 73. These RMDs are taxable and can push you into a higher tax bracket. Roth 401(k)s, however, are no longer subject to RMDs starting in 2024, according to the IRS. This makes Roth accounts more flexible for those who don't need the money and want to leave it to heirs.

Mistake 4: Assuming employer matches are tax-free if you contribute to a Roth

Employer matches are always made with pre-tax dollars, regardless of whether you choose Roth or traditional contributions. That means the match and its earnings will be taxed when you withdraw them. Some plans allow you to convert the match to Roth, but that triggers a tax bill. Don't expect your entire 401(k) balance to be tax-free just because you elected Roth contributions.

The risks

Investing in a 401(k) involves risk, including the possibility of losing money. The stock market can go down, and your account balance can fall, especially in the short term. Diversification and a long time horizon can help, but they don't guarantee returns. Also, tax laws can change. While Roth accounts currently offer tax-free withdrawals, Congress could alter the rules in the future. That's a risk to consider, but it's not a reason to avoid saving for retirement altogether.

Putting it together

The choice between a traditional and Roth 401(k) comes down to when you want to pay taxes: now or later. If you expect to be in a higher tax bracket in retirement, Roth may be more appealing. If you expect a lower bracket, traditional might be better. Many people choose to contribute to both to create tax diversification, giving you flexibility to manage your tax bill in retirement. For more on retirement planning, explore our investing hub or use the 401(k) calculator to estimate your future balance.