Simple definition
A Roth 401(k) is a workplace retirement account funded with money you've already paid taxes on. Because you pay tax up front, qualified withdrawals in retirement — including all the growth — come out tax-free. It's the after-tax twin of a traditional 401(k). Think of it like paying tax on the seed now so you can harvest the whole crop tax-free later. The IRS sets contribution limits and adjusts them annually.
Why it matters
A Roth 401(k) lets you lock in today's tax rate and enjoy tax-free income in retirement — powerful if you expect to be in the same or a higher tax bracket later. Combined with an employer match, it's one of the strongest retirement tools available through work.
Real-life example
You contribute $200 from each paycheck to your Roth 401(k) with after-tax dollars, so your take-home pay drops by the full $200. Decades later, that money — plus all its growth — can be withdrawn completely tax-free in retirement. Your employer may still match contributions, though the match typically goes into a pre-tax bucket.
Common mistakes
- Skipping the employer match — that's free money left on the table.
- Assuming employer matching dollars are also tax-free; the match is usually pre-tax.
- Choosing Roth when you're in a high bracket now and expect a much lower one later.
- Guessing the contribution limit instead of checking the current IRS figure.
Pro tips
- Contribute at least enough to capture the full employer match.
- Consider Roth if you expect your tax rate to be as high or higher in retirement.
- Confirm the current contribution limit on IRS.gov, since it changes yearly.
- You can often split contributions between the Roth and traditional buckets.
Related Money Dictionary terms
- 401(k)A retirement account through your job, often with an employer match — free money for saving.
- Roth IRAA retirement account funded with after-tax money that grows and comes out tax-free.
- Roth ConversionMoving money from a pre-tax retirement account into a Roth account and paying the taxes now for tax-free growth later.
- Employer MatchMoney your company adds to your retirement account based on how much you contribute, effectively free money toward your savings.
- Contribution LimitThe maximum amount the government lets you put into a retirement account in a single year.
- Traditional IRAA retirement account where contributions may lower your taxable income now and you pay tax when you withdraw later.
Frequently asked questions
What's the difference between a Roth 401(k) and a traditional 401(k)?
It's about when you pay taxes. A traditional 401(k) uses pre-tax money, lowering your taxes now but taxing withdrawals later. A Roth 401(k) uses after-tax money, so you get no break now but qualified withdrawals are tax-free in retirement. Which wins depends on your tax rate now versus later.
Is the employer match tax-free too?
Usually not. Even in a Roth 401(k), employer matching contributions typically go into a separate pre-tax account, so you'll owe ordinary income tax on that portion and its growth when you withdraw it in retirement. Only your own Roth contributions and their growth come out tax-free if qualified.
How much can I put in a Roth 401(k)?
Contribution limits are set by the IRS and adjusted each year, and they're a combined cap whether you use the Roth or traditional side of your 401(k). Because the figure changes annually, check IRS.gov for the current limit rather than relying on a number you saw before.
Knowing what Roth 401(k) means is knowledge — the first half. A brick gets placed when you act on it: check whether your employer's 401(k) offers a Roth option and whether you're getting the full match.
Also builds: Retirement Accounts
Sources & references
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Plain-English education — not personalized legal, tax, or investment advice.