Traditional 401(k) vs. Roth 401(k): When Taxes Are Paid
In brief
Traditional and Roth 401(k) deferrals use the same workplace plan and combined employee limit, but traditional deferrals generally postpone income tax while Roth deferrals are included in current taxable income.
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The main idea
The choice is primarily about tax timing under uncertain future rates; plan quality, matching, investments, and fees are shared account questions that remain important either way.
At a glance
2026 combined deferral limit
$24,500
Traditional and designated Roth employee deferrals share this limit before eligible catch-up contributions.
Internal Revenue Service ↗Traditional contribution
Generally pre-tax
Elective deferrals generally reduce current federal taxable income; distributions are generally taxable.
Internal Revenue Service ↗Roth contribution
After-tax
Included in current income; qualified distributions can be tax-free.
Internal Revenue Service ↗One plan, two tax treatments
A traditional 401(k) deferral and a designated Roth 401(k) contribution are elections inside an employer plan. They are not separate annual limits. A participant may split contributions between them when the plan permits, but the combined employee deferrals cannot exceed the applicable limit.
For 2026, that employee elective-deferral limit is $24,500 before an eligible catch-up contribution. Employer contributions and the plan's overall contribution limit are separate concepts.
Compare the marginal tax rate on each side
Traditional deferrals generally avoid current federal income tax and are generally taxable when distributed. Roth deferrals are taxed now; qualified distributions of contributions and earnings can be tax-free after the applicable five-year and qualifying-event requirements.
The cleanest comparison asks whether the tax rate avoided today is higher or lower than the marginal rate applied to future withdrawals. That future rate is unknown and can be affected by other income, filing status, state residence, Social Security, required distributions, and changes in law.
Do not ignore cash flow and plan design
The same gross deferral reduces take-home pay differently because Roth contributions do not reduce current taxable income. Compare equal reductions in spending capacity when testing outcomes; comparing equal account deposits can hide the current tax cost of Roth contributions.
Matching rules, vesting, investment menus, fees, loans, and distribution options come from the plan. Review how the current plan handles matching and Roth features rather than assuming every employer implements the same options.
Splitting contributions can manage uncertainty
Using both treatments can create future tax flexibility, but it does not guarantee a lower lifetime tax bill. A split may be useful when the rate comparison is close or the participant wants multiple withdrawal sources.
Revisit the election after material changes in income, filing status, state taxes, plan terms, or retirement timing. Do not switch solely because markets rose or fell; market direction does not determine which tax rate applies.
Before acting
Questions to verify
- Confirm the plan offers a designated Roth feature.
- Add traditional and Roth deferrals together when checking the annual limit.
- Compare equal take-home-pay costs, not only equal deposits.
- Estimate current marginal tax rate without treating a future rate as known.
- Read the plan's match, vesting, fee, and distribution provisions.
Continue the retirement cluster