Roth 401(k) vs. Traditional 401(k): Same Contribution or Same Take-Home Pay?
In this guide
A useful Roth 401(k) vs traditional 401(k) comparison begins by deciding what stays equal. A $10,000 Roth contribution and a $10,000 traditional contribution put the same nominal amount into the account, but they do not usually have the same effect on current take-home pay. Traditional elective deferrals generally reduce current federal taxable income; Roth contributions are made after tax.
That means “same contribution” and “same take-home cost” answer different questions. Neither comparison predicts which account will be better, because future tax rates, withdrawals, investment returns, state taxes, and household circumstances remain uncertain.
Comparison One: Put the Same Amount Into Each Account
Assume a worker is deciding where to direct $10,000 and has a simplified 22% current federal marginal tax rate. A $10,000 traditional 401(k) deferral could reduce current federal income tax by roughly $2,200, ignoring state tax, payroll tax, deductions, credits, and tax-bracket interactions. The worker gets $10,000 invested while current take-home pay falls by roughly $7,800 under this narrow illustration.
A $10,000 Roth 401(k) contribution does not receive that current federal income-tax reduction. The account still receives $10,000, but take-home pay falls by roughly the full $10,000 in the simplified example. The Roth contribution therefore requires about $2,200 more current cash flow than the traditional contribution.
| Same $10,000 contribution | Traditional | Roth |
|---|---|---|
| Amount invested | $10,000 | $10,000 |
| Simplified current federal tax effect at 22% | About $2,200 reduction | No current reduction |
| Simplified take-home reduction | About $7,800 | About $10,000 |
This is not a tax return calculation. Payroll withholding and final tax liability are different, and a contribution can cross tax brackets rather than saving one rate on every dollar.
Comparison Two: Hold the Take-Home Cost Equal
Now assume the worker can afford a $7,800 reduction in current take-home pay. Under the same simplified 22% assumption, a $10,000 traditional contribution has that approximate after-tax cost. A Roth contribution with the same immediate budget cost would be about $7,800.
Traditional starts with more money invested in this comparison, but future qualified withdrawals from Roth accounts generally receive different federal tax treatment from taxable traditional withdrawals. A fair long-term model must account for taxes on the traditional balance or invest the traditional tax savings outside the plan. Simply comparing a $10,000 traditional account with a $7,800 Roth account while ignoring all future tax effects is incomplete.
The Core Question Is Often Your Tax Rate Across Time
Traditional contributions tend to look more attractive when the tax rate avoided today is higher than the effective rate eventually paid on withdrawals. Roth contributions tend to look more attractive when the tax cost today is lower than the rate that would otherwise apply later. The difficult part is that future tax law, income, deductions, location, filing status, and withdrawal strategy are unknown.
Retirement tax rates do not depend only on salary replacement. Social Security benefits, pensions, required distributions, brokerage income, and a spouse's accounts can fill tax brackets. Conversely, a retiree may have years between work and required distributions when taxable income is relatively low. The choice can also be diversified: many plans allow contributions to be split between Roth and traditional within the combined employee limit.
Employer Match Does Not Create a Second Employee Limit
For 2026, the regular employee elective-deferral limit is $24,500, with applicable catch-up amounts based on age. Roth and traditional employee deferrals share that limit. Contributing $12,250 to each would reach $24,500; it would not leave another $24,500 available.
Employer contributions operate under plan rules and the separate overall annual additions limit. Ask how your plan accounts for employer contributions and whether matching dollars are designated in a particular tax source. The 2026 contribution limit guide explains the separate buckets.
Questions That Matter More Than a Generic Rule
- What is your current marginal federal and state income-tax rate?
- Would a traditional contribution qualify you for or preserve a deduction, credit, or income-based benefit?
- Can you afford the larger current take-home reduction of an equal Roth contribution?
- Will you actually save or invest the tax savings from a traditional contribution?
- How much tax diversification already exists across your retirement accounts?
- What withdrawal flexibility, estate goals, or early-retirement years may affect future taxable income?
A Practical Decision Process
First contribute enough to capture an available employer match if the household budget can support it. Next compare both ways: equal dollars contributed and equal take-home cost. Use more than one current and future tax-rate assumption. Finally, remember that contribution rate often matters more than finding a perfect tax label. A thoughtful 12% savings rate split across both sources may do more for retirement readiness than a precisely optimized 5% rate.
This is educational information, not individualized tax advice. Use current payroll estimates and consult a qualified tax professional for interactions involving credits, state taxes, high income, business ownership, or complex retirement distributions.
Two valid but different comparisons
At a simplified 22% current federal rate, $10,000 in traditional contributions may have an approximate $7,800 take-home cost. You can compare that with a $10,000 Roth contribution to hold account deposits equal, or with about a $7,800 Roth contribution to hold current take-home cost equal. State tax and personal tax details can materially change both figures.