If your employer offers both a traditional and a Roth 401(k), you have a real choice to make — and it is one that can affect how much tax you pay across your working and retirement years. The core difference comes down to timing: when do you want to pay the tax on this money?
How a traditional 401(k) works
With a traditional 401(k), contributions come out of your paycheck before income tax is applied. This reduces your taxable income today, meaning you pay less tax in the year you contribute. The money then grows tax-deferred, and you pay ordinary income tax when you withdraw it in retirement.
This structure benefits you most if you are currently in a higher tax bracket than you expect to be in retirement. You defer tax from a high-rate year to a lower-rate one.
How a Roth 401(k) works
With a Roth 401(k), contributions come from money you have already paid tax on — after-tax dollars. The trade-off is that growth and qualified withdrawals in retirement are entirely tax-free. You pay the tax now, and nothing more is owed later.
This structure benefits you most if you expect to be in a higher tax bracket in retirement than you are today, or if you value having tax-free income available in retirement for flexibility and planning purposes.
Key differences at a glance
- Tax on contributions: Traditional = pre-tax; Roth = after-tax
- Tax on withdrawals: Traditional = taxable; Roth = tax-free (if qualified)
- RMDs: Traditional 401(k)s require minimum distributions from age 73 (75 if you were born in 1960 or later); since 2024, Roth 401(k)s have no lifetime RMDs
- Income limits: Neither traditional nor Roth 401(k)s have income limits for contributions, unlike Roth IRAs
- Contribution limits: Same for both — $24,500 in 2026, plus an $8,000 catch-up if 50 or older ($11,250 if 60 to 63)
Who tends to benefit more from each?
A traditional 401(k) often makes more sense if you are in your peak earning years and expect a lower income in retirement. The tax break today has real value when your rate is high.
A Roth 401(k) often makes more sense if you are earlier in your career, expect income to grow significantly, or anticipate that tax rates will be higher in the future than they are today. It also makes sense if you want tax diversity in retirement — having some money you can access without triggering additional taxable income.
Can you split contributions between both?
Yes. If your plan offers both options, you can split your contributions in any proportion you choose, as long as the total stays within the annual limit. Some people deliberately do this to hedge against uncertainty about future tax rates.
What about employer matching contributions?
Employer matching contributions go into a traditional (pre-tax) account regardless of whether you are making Roth contributions. When you withdraw employer match funds in retirement, those withdrawals will be taxable.
Want a clearer picture of how these choices affect your retirement income?
The Essential 401(k) & IRA Retirement Guide covers both account types in depth — including how they interact with Social Security, RMDs, and broader tax planning. A practical read for anyone making decisions about their retirement accounts.
