A Roth 401k is a workplace retirement account that you fund with after-tax dollars, so qualified withdrawals in retirement — including the growth — come out tax-free. It combines the structure of a 401k, including the high contribution limit and any employer match, with the after-tax treatment of a Roth account. In 2026 many employers offer a Roth 401k option right alongside the traditional pre-tax version, letting you choose when you pay the tax: now, or in retirement. The right choice hinges on whether you expect your tax rate to be higher today or later. This is general information, not personalized advice; verify your own situation.
How a Roth 401k works
You contribute money that has already been taxed, so there is no upfront tax break. In exchange, qualified withdrawals in retirement are tax-free, which means decades of investment growth can come out without a tax bill.
Key traits in 2026:
- After-tax contributions with no immediate deduction.
- Tax-free qualified withdrawals, generally after age 59 and a half and a five-year holding rule.
- High contribution limit, the same large 401k cap that far exceeds an IRA.
- No income limit to contribute, unlike a Roth IRA which phases out at higher incomes.
One wrinkle: any employer match is contributed on a pre-tax basis into a separate bucket, so the matched portion is taxed when you withdraw it.
Roth 401k vs traditional 401k
The core difference is timing of taxes.
| Feature |
Roth 401k |
Traditional 401k |
| Contributions |
After-tax |
Pre-tax |
| Upfront tax break |
No |
Yes |
| Withdrawals |
Tax-free if qualified |
Taxed as income |
| Contribution limit |
Same high 401k limit |
Same high 401k limit |
| Employer match |
Pre-tax, taxed later |
Pre-tax, taxed later |
| Income limit to contribute |
None |
None |
A traditional 401k lowers your taxable income now. A Roth 401k gives up that break for tax-free income later. For the broader account-ordering question, see Roth IRA vs 401k.
How to choose between Roth and traditional
- Compare your tax rate now vs later. If you expect a higher rate in retirement, Roth often wins. If lower, traditional may.
- Consider your career stage. Early-career workers in lower brackets frequently favor Roth.
- Think about tax diversification. Holding both gives you flexibility to manage taxable income in retirement.
- Capture the match either way. Whatever you pick for your own contributions, fund enough to get the full employer match.
What to skip
- Assuming Roth is always best. It depends on your current versus future tax rate, which is genuinely uncertain.
- Forgetting the match is pre-tax. The employer portion is taxed at withdrawal even in a Roth 401k.
- Skipping the five-year rule. Tax-free withdrawals require meeting both the age and holding-period conditions.
- Treating it like a Roth IRA. They share after-tax treatment but differ on limits, rules, and investment choice.
FAQ
What is the difference between a Roth 401k and a traditional 401k?
A Roth 401k uses after-tax contributions for tax-free withdrawals later; a traditional 401k uses pre-tax contributions and taxes withdrawals. The choice depends on your expected tax rate.
Is the employer match tax-free in a Roth 401k?
No. The match is contributed pre-tax into a separate account and is taxed when you withdraw it, even though your own Roth contributions are tax-free.
Can I have both a Roth 401k and a Roth IRA?
Yes, if you are eligible. They are separate accounts with separate rules; the 401k has a far higher limit, while the IRA offers broader investment choice.
Is there an income limit for a Roth 401k?
No. Unlike a Roth IRA, a Roth 401k has no income cap on contributions, which makes it attractive for higher earners.
Where to go next
Read Roth IRA vs 401k in 2026, traditional 401k vs Roth 401k in 2026, and is a Roth IRA worth it in 2026.