How a Roth 401(k) Works and How It Differs From a Traditional 401(k)

A Roth 401(k) lets you contribute after-tax money now and withdraw it tax-free in retirement, the opposite of a traditional 401(k)

A Roth 401(k) is an employer-sponsored retirement account where you contribute money that has already been taxed. The money grows tax-free, and when you withdraw it in retirement, you pay no federal income tax on those withdrawals. A traditional 401(k) works the other way: you contribute pre-tax money (reducing your taxable income today), but you pay income tax on withdrawals later. Both are 401(k) accounts offered by your employer; the difference is when the tax bill arrives.

Not every employer offers a Roth 401(k). If your company plan includes one, you choose which type of account to use when you enroll, or you can split contributions between both. The contribution limits, employer match rules, and withdrawal penalties are the same for both versions. The only difference that matters is the tax treatment.

Key Takeaways

• Roth 401(k) contributions come from your after-tax pay, so they do not lower your taxable income in the year you contribute.
• Withdrawals from a Roth 401(k) in retirement are tax-free, unlike traditional 401(k) withdrawals, which are taxed as ordinary income.
• Both Roth and traditional 401(k)s have the same annual contribution limits and employer match rules; the difference is only when you pay tax.
• Roth 401(k)s are useful if you expect to be in a higher tax bracket in retirement or want to reduce taxable income later.
• Unlike Roth IRAs, Roth 401(k)s have required minimum distributions starting at age 73, and there is no income limit to contribute.

How contributions and taxes work in a Roth 401(k)

When you contribute to a Roth 401(k), the money comes out of your paycheck after federal income tax, Social Security tax, and Medicare tax have already been withheld. Your employer does not reduce your taxable income for that contribution. If you earn $60,000 and contribute $7,000 to a Roth 401(k), you still report $60,000 as your income on your tax return.

Your employer can still contribute a match to your Roth 401(k). That employer match goes into a separate account within the plan and is treated as pre-tax money. When you withdraw the employer match portion in retirement, you pay tax on it. Only your own contributions and their earnings come out tax-free.

The money in your Roth 401(k) grows without being taxed each year. If you invest in mutual funds or stocks inside the account, you do not report the gains, dividends, or interest on your annual tax return. That tax-free growth continues until you withdraw the money.

Roth 401(k) versus traditional 401(k) in side-by-side comparison

Feature	Roth 401(k)	Traditional 401(k)
Contribution type	After-tax dollars	Pre-tax dollars
Reduces your taxable income this year	No	Yes
Withdrawals in retirement are taxed	No (your contributions and earnings are tax-free)	Yes (all withdrawals are taxed as ordinary income)
Employer match treatment	Employer match is pre-tax; you pay tax on it when withdrawn	Employer match is pre-tax; you pay tax on it when withdrawn
2024 contribution limit	$23,500 (age 50+: $31,000)	$23,500 (age 50+: $31,000)
Income limit to contribute	None	None
Required minimum distributions at age 73	Yes	Yes

Who might choose a Roth 401(k) over a traditional 401(k)

A Roth 401(k) makes sense if you believe your tax rate will be higher in retirement than it is now. If you are early in your career, earning a modest salary, and expect significant income growth, paying tax at your current lower rate and withdrawing tax-free later can save money. The longer the money sits in the account, the more tax-free growth you capture.

A Roth 401(k) is also useful if you want to reduce the amount of taxable income you must report in retirement. Required minimum distributions from a traditional 401(k) count as taxable income and can push you into a higher tax bracket, affect your Medicare premiums, or reduce other benefits. Roth withdrawals do not count as income, so they do not trigger those effects.

Some people use both accounts. You can contribute to a Roth 401(k) and a traditional 401(k) in the same year, as long as your combined contributions do not exceed the annual limit. This approach, called "splitting," lets you hedge against uncertainty about future tax rates.

Withdrawal rules and penalties for Roth 401(k)s

You can withdraw your own contributions to a Roth 401(k) at any time without penalty or tax, even before retirement. However, withdrawing the earnings (the investment gains) before age 59½ triggers a 10 percent early withdrawal penalty and income tax on those earnings, unless an exception applies. Exceptions include disability, death, or a few other narrow circumstances.

Unlike a Roth IRA, a Roth 401(k) requires you to take minimum distributions starting at age 73. The amount is calculated based on your age and account balance using IRS tables. If you do not take the required amount, you owe a 25 percent penalty on the shortfall (reduced to 10 percent if you correct it within two years).

One workaround: if you still work and your employer plan allows it, you can delay required distributions from that employer's plan until you actually retire. This rule does not explore to IRAs or plans from previous employers.

Roth 401(k) versus Roth IRA: key differences

A Roth 401(k) and a Roth IRA both offer tax-free growth and withdrawals, but they have different rules. A Roth IRA has no required minimum distributions during your lifetime, so you can leave the money untouched as long as you want. A Roth 401(k) requires distributions starting at age 73.

A Roth IRA has income limits: if you earn above a certain threshold, you cannot contribute directly. A Roth 401(k) has no income limit, so high earners can use it to save more in a Roth account. A Roth 401(k) also has much higher contribution limits ($23,500 in 2024, compared to $7,000 for a Roth IRA).

If your employer does not offer a Roth 401(k), you can still open a Roth IRA on your own, as long as your income is below the limit. Many people use both: they contribute to their employer's Roth 401(k) and also fund a Roth IRA separately.

Converting a traditional 401(k) to a Roth 401(k)

Some employers allow in-plan Roth conversions, which let you move money from a traditional 401(k) to a Roth 401(k) within the same plan. When you do this, you owe income tax on the amount you convert in that tax year. The converted money then grows tax-free and can be withdrawn tax-free in retirement.

An in-plan conversion is different from a Roth IRA conversion. With an IRA conversion, you move money from a traditional IRA to a Roth IRA and pay tax on the conversion. Both strategies have the same goal: moving pre-tax money into a tax-free account. Not all employers offer in-plan conversions, so check your plan documents or ask your benefits administrator.

Frequently Asked Questions

Can I contribute to both a Roth 401(k) and a traditional 401(k) in the same year?

Yes. Your combined contributions to both accounts cannot exceed the annual limit ($23,500 in 2024, or $31,000 if you are 50 or older). If you contribute $10,000 to a Roth 401(k), you can contribute up to $13,500 to a traditional 401(k) that same year, as long as your employer offers both.

Do I have to pay taxes on my employer match in a Roth 401(k)?

Yes. Your employer's matching contribution is always pre-tax money, even in a Roth 401(k). It goes into a separate account within the plan, and you pay ordinary income tax on it when you withdraw it in retirement. Only your own contributions and their earnings are tax-free.

What happens to my Roth 401(k) if I leave my job?

You can roll the Roth 401(k) into a Roth IRA at another financial institution. This move does not trigger taxes or penalties. A Roth IRA also has no required minimum distributions during your lifetime, which is an advantage over keeping the money in a Roth 401(k).

Can I withdraw money from my Roth 401(k) before retirement?

You can withdraw your own contributions anytime without penalty or tax. Withdrawing earnings before age 59½ triggers a 10 percent penalty and income tax on those earnings, unless you may have access to for an exception like disability or death. Your employer match is always subject to the early withdrawal penalty if taken before 59½.

Is there an income limit to contribute to a Roth 401(k)?

No. Unlike a Roth IRA, a Roth 401(k) has no income limit. High earners who cannot contribute to a Roth IRA can use a Roth 401(k) if their employer offers it. This makes it a valuable tool for saving in a tax-free account regardless of how much you earn.