Traditional 401(k) vs Roth 401(k)
A Traditional 401(k) takes contributions out of your paycheck before income tax — you pay tax later, when you withdraw in retirement. A Roth 401(k) takes contributions after tax — you pay tax now, but qualified withdrawals are tax-free. Which is better depends almost entirely on whether your tax rate today is higher or lower than your expected rate in retirement.
Last reviewed on 2026-04-27.
Quick Comparison
| Aspect | Traditional 401(k) | Roth 401(k) |
|---|---|---|
| When tax is paid | At withdrawal | At contribution |
| Contribution treatment | Pre-tax — reduces taxable income | After-tax — no current-year deduction |
| Growth | Tax-deferred | Tax-free if rules followed |
| Qualified withdrawal | Taxed as ordinary income | Tax-free (account 5+ years old, age 59½+) |
| Required minimum distributions | Yes, starting at the age set by current law | Yes (rules vary; check current IRS guidance) |
| Same contribution limit? | Yes — combined limit across both within a 401(k) plan | Yes |
| Employer match treatment | Match goes into pre-tax bucket regardless of which you choose | Same |
Key Differences
1. Pay tax now or pay tax later
A Traditional 401(k) contribution lowers your taxable income this year. The money grows tax-deferred. When you withdraw in retirement, every dollar comes out as ordinary income subject to whatever your marginal rate is at that time.
A Roth 401(k) contribution doesn't lower this year's taxable income. The money grows, and qualified withdrawals — typically after 59½ and after the account has been open at least five years — come out tax-free.
2. The break-even logic
Traditional wins if your retirement marginal tax rate is lower than today's. You skipped a higher tax rate at contribution and pay a lower rate at withdrawal.
Roth wins if your retirement marginal tax rate is higher than today's. You paid a lower rate now and avoid a higher rate later.
3. When each tends to fit
Traditional often makes sense for higher earners now who expect retirement income to be lower (and therefore taxed at a lower marginal rate).
Roth often makes sense for lower earners now (e.g., early-career), people in low-tax states moving to high-tax states, or anyone who expects significantly higher retirement income or future tax rates.
4. Required minimum distributions and tax planning
Traditional 401(k)s have RMDs starting at the age set by current law. That can push retirement income — and tax brackets — higher than a retiree wants.
Roth 401(k)s have similar RMDs from the workplace plan, but they're typically rolled to a Roth IRA in retirement (no RMDs) — a common planning step.
5. Employer match
Employer match always goes into a pre-tax bucket, even if you're contributing to a Roth 401(k). At retirement, that bucket is taxed as Traditional money would be.
That's why many people end up with a mix of Roth and Traditional balances even if they only contribute Roth — the match is automatically Traditional.
6. Contribution limits
Combined. The annual 401(k) employee contribution limit applies across both Traditional and Roth elective deferrals.
You can split contributions between Traditional and Roth in whatever ratio fits your plan, as long as the total stays within the limit.
When to Choose Each
Choose Traditional 401(k) if:
- You expect a lower tax bracket in retirement than you have now.
- You're a high earner today who wants the immediate tax deduction.
- You're fine with paying tax on withdrawals from this account in retirement.
- Your employer doesn't offer a Roth option (it's the only choice).
Choose Roth 401(k) if:
- You're early-career or in a low-tax year now.
- You expect higher taxable income in retirement (large pensions, taxable accounts, RMDs from other Traditional balances).
- You expect future tax rates to be higher than today's.
- You want tax diversification across pre-tax and after-tax buckets.
Worked example
A 28-year-old in a 22% marginal bracket who expects to be in a 32% bracket later in her career chooses Roth 401(k) — pay the lower rate now. A 50-year-old at the peak of her earning years, currently in a 35% bracket and expecting to retire to a 24% bracket, chooses Traditional — get the deduction now and pay the lower rate later. Same plan rules; very different optimal answers depending on the lifecycle stage.
Common Mistakes
- "Roth is always better because tax-free." Only if your retirement bracket is similar or higher. Otherwise, paying high rates now to avoid lower rates later costs you.
- "I can't do Roth because I make too much." That's the Roth IRA income limit, not the Roth 401(k). Roth 401(k) has no income limit.
- "The match goes into the same Roth bucket." No — employer match always lands in pre-tax even if you're contributing Roth.
- "You can't split contributions." You can — many people contribute to both buckets in the same year for tax diversification.
This is general educational information, not personalised advice. See the disclaimer for the full note.