Roth vs Traditional 401(k): The Real Paycheck Difference in 2026

Quick Answer: How much smaller is your paycheck on Roth vs Traditional 401(k)?

At a 10% deferral on a $75,000 salary (biweekly, single filer, no state income tax), the Roth 401(k) reduces your net pay by about $63 more per paycheck than the Traditional option. That works out to roughly $1,650 a year. The dollar amount you contribute is the same either way. The only paystub line that moves is federal income tax withholding, because Traditional contributions shrink your taxable wages and Roth contributions do not.

Social Security and Medicare are identical under both choices. That is the FICA wash, and it is the most misunderstood part of this question.

The Short Answer: How Much Less Is Your Paycheck on Roth?

If you switch your 401(k) election from Traditional to Roth, your next paycheck will shrink by an amount roughly equal to your contribution times your federal marginal tax rate.

For a single filer earning $75,000 in Texas, paid biweekly, deferring 10% with no other deductions and no W-4 dependents, the 2026 numbers look like this:

• No 401(k): $2,368.94 net per paycheck
• Traditional 401(k) at 10%: $2,143.94 net
• Roth 401(k) at 10%: $2,080.48 net

The Roth choice costs $63.46 more per paycheck than Traditional, or about $1,650 a year. That is not lost money. It is the federal income tax that the Traditional option defers until retirement, paid up front so future withdrawals come out tax-free.

The framing most articles miss is that the deferral itself is the same dollar amount. $288.46 leaves your paycheck either way at 10% on $75,000. What changes is whether the IRS gets its cut now (Roth) or later (Traditional).

What's Identical: FICA, Gross Pay, and the Contribution Amount

Three lines on your paystub do not move when you toggle between Roth and Traditional:

Gross wages

Your gross pay is whatever your salary divided by pay periods says it is. The 401(k) election does not change your salary, so the top of the paystub is unchanged.

The FICA wash

Both Roth and Traditional 401(k) employee deferrals are subject to Social Security and Medicare withholding. The IRS is explicit on this in its retirement plan FAQs: elective deferrals reduce federal income taxable wages but not FICA wages. So 6.2% Social Security and 1.45% Medicare apply to your full gross pay either way. On a $2,884.62 biweekly gross, that is $178.85 + $41.83 = $220.68 of FICA, every paycheck, under either election.

This is the part most people get wrong. They assume Roth means "after-tax" so it must avoid more taxes than Traditional, or they assume Traditional dodges payroll taxes too. Neither is correct. The FICA line is a tie.

The contribution amount

10% of $2,884.62 is $288.46. That dollar leaves your paycheck and lands in your 401(k) regardless of whether it goes into the Roth bucket or the Traditional bucket. Same outflow, same retirement balance starting point.

The only line that actually shifts is federal income tax withholding, plus state income tax in states that have one.

What Changes: Federal Income Tax Withholding

Federal income tax withholding is calculated by your employer using IRS Publication 15-T. The input is your taxable wages, which is gross pay minus pre-tax deductions. This is the only place where Roth and Traditional diverge.

Traditional shrinks taxable wages

A Traditional 401(k) deferral comes out of gross pay before federal income tax is calculated. On the $75K example, taxable wages drop from $2,553.85 (gross minus standard withholding allowance) to $2,265.38, and federal withholding drops from $295.00 to $231.54. That is a $63.46 reduction in tax withheld, which is exactly the difference you see between the Traditional and Roth net pay numbers.

Roth leaves taxable wages alone

A Roth 401(k) deferral happens after federal income tax is calculated. Taxable wages stay at $2,553.85, withholding stays at $295.00, and then the $288.46 deferral comes out of what is left. The result is the lowest net pay of the three scenarios.

So the per-paycheck delta between Roth and Traditional is approximately:

delta = deferral_amount × marginal_federal_rate

At $75K single, the marginal rate is 22%. $288.46 × 22% = $63.46, which matches the actual paystub math to the penny.

Paycheck Difference at $50K, $75K, and $100K

The Roth-vs-Traditional gap depends on which federal tax bracket your last dollar of taxable wages sits in. Below is the same scenario (single filer, biweekly, 10% deferral, no state income tax) repeated at three salaries using 2026 tax tables.

Summary table

• $50,000 salary (12% bracket): Traditional nets $1,459.81, Roth nets $1,436.73. Delta is $23.08 per paycheck, about $600/year. Deferral amount: $192.31.
• $75,000 salary (22% bracket): Traditional nets $2,143.94, Roth nets $2,080.48. Delta is $63.46 per paycheck, about $1,650/year. Deferral amount: $288.46.
• $100,000 salary (22% bracket): Traditional nets $2,745.38, Roth nets $2,660.77. Delta is $84.62 per paycheck, about $2,200/year. Deferral amount: $384.62.

Two patterns to notice. First, the delta grows with income because both the contribution and the marginal rate climb. Second, the jump from $50K to $75K is bigger than the jump from $75K to $100K, because $50K crosses the 12% to 22% bracket boundary while $75K and $100K share the same 22% bracket.

If your salary sits between these rows, the rough estimate is your biweekly deferral times your federal marginal rate. Run your own number through our Paycheck Calculator to see the exact figure with your filing status and W-4 settings.

Does State Income Tax Change the Answer?

Yes, in the same direction and for the same reason. Most states that tax wage income honor the federal pre-tax treatment of Traditional 401(k) contributions, so going Traditional shrinks state taxable wages too. Roth does not. That widens the per-paycheck gap.

Texas vs California, $75K

The $75,000 single filer in Texas saw a $63.46 biweekly delta. The same earner in California sees:

• Traditional 10%: $2,007.97 net per paycheck
• Roth 10%: $1,919.12 net per paycheck
• Delta: $88.85, or about $2,310/year

That extra $25.39 per paycheck on top of the federal $63.46 is the California state-tax wedge. California taxes the Roth contribution as ordinary income today; Traditional defers it.

If you live in Florida, Texas, Tennessee, Washington, or another state with no income tax, your Roth-vs-Traditional decision is purely a federal one. If you live in a high-tax state, the upfront cost of Roth is meaningfully larger, but so is the future tax benefit if you retire in a low-tax or no-tax state.

2026 Contribution Limits and the New Roth Catch-Up Rule

The IRS announced the 2026 limits in October 2025. Two of them affect Roth-vs-Traditional decisions directly.

Standard limits

• 401(k) elective deferral: $24,500 (up from $23,500 in 2025).
• Age 50+ catch-up: $8,000 (up from $7,500).
• Age 60 to 63 super catch-up: $11,250 (unchanged).
• Combined Roth and Traditional: the limit applies across both buckets in the same plan.

That means the most you can defer in 2026 is $24,500 if you are under 50, $32,500 if you are 50 to 59 or 64+, and $35,750 if you are 60 to 63. Splitting between Roth and Traditional does not raise the cap.

New for 2026: high-earner Roth catch-up rule

This is the biggest 401(k) rule change since the original Roth option was added. If your prior-year FICA wages from the employer that sponsors your 401(k) exceeded $150,000, your age 50+ catch-up contributions in 2026 must be made as Roth. The base $24,500 deferral is still your choice between Roth and Traditional.

The $150,000 trigger is per-employer and based on Social Security wages, not total household income. If you switched jobs mid-2025 and neither employer paid you over $150K, you can still choose Traditional for catch-up in 2026. Plans without a Roth option are temporarily allowed to disable catch-ups for high earners until they add Roth functionality.

The 2026 Social Security wage base also rose to $184,500. That is the cap on Social Security tax (not Medicare), and it does not change the FICA wash described above.

Which One Wins Long-Term? A Simple Framework

The paycheck math is just the upfront cost of admission. The actual decision rests on a single question: will your tax rate be higher now or in retirement?

Traditional usually wins if

• You are at peak earnings and expect to retire in a lower bracket.
• You live in a high-tax state now and plan to retire to a no-tax state.
• You need the immediate cash flow relief and would otherwise reduce your contribution rate.

Roth usually wins if

• You are early in your career with room for promotions and raises.
• You expect federal tax rates to rise (the 2017 Tax Cuts and Jobs Act brackets were extended in 2025, but rates can still change in the future).
• You already have a large Traditional balance and want tax diversification at retirement.
• You want to leave tax-free assets to heirs.

The split strategy

Many 401(k) plans let you divide each paycheck's deferral between Roth and Traditional. A 50/50 split hedges the bet and gives you two buckets to draw from in retirement. In retirement, you can pull from the Traditional bucket up to the top of a low bracket, then top up living expenses from the Roth bucket without pushing into a higher bracket.

One mental model that helps: $288 contributed to Roth and $288 contributed to Traditional are not equal in retirement value. The Traditional balance is partly the government's, since you owe ordinary income tax on withdrawals. The Roth balance is entirely yours. To compare apples to apples, you would need to gross up the Traditional contribution by your future tax rate, or shrink the Roth contribution by your current rate.

Run a few scenarios through our Paycheck Calculator to see how each option lands on your next paystub before changing your election in your employer's portal.

2026 Paycheck Examples

Each example uses 2026 federal tax tables, single filing status, biweekly pay, no W-4 dependents, and a 10% 401(k) deferral unless noted. Numbers come from the EHM Tech Paycheck Calculator engine and assume no other pre-tax deductions.

Frequently Asked Questions

Practical Tips Before You Switch

• Run your own paycheck math first. The deltas in this article assume specific filing statuses and zero other deductions. Plug your real salary, state, and W-4 settings into our Paycheck Calculator before changing your election.
• Don't double-count your tax savings. The Traditional option's lower withholding is not free money. It is tax you'll owe on retirement withdrawals. Compare apples to apples by adjusting one balance for future tax owed.
• Check your employer match treatment. Most plans deposit the employer match into a Traditional bucket regardless of your employee election. So even a 100% Roth contributor often ends up with mixed balances over time.
• Update your W-4 if cash flow changes. Switching from Traditional to Roth raises your withholding automatically, but if you also bumped your contribution rate, run the IRS Tax Withholding Estimator to confirm your year-end balance is still on track.
• Consider a split rather than a binary choice. Many plans let you allocate a percentage to each bucket. A 50/50 split hedges your tax-rate uncertainty without committing fully to either side.
• Watch the 2026 catch-up rule if you are 50+. If your 2025 Social Security wages from your current employer topped $150,000, your catch-up contributions in 2026 must be Roth. Plan ahead to make sure the cash flow works.

References

• IRS: 401(k) Limit Increases to $24,500 for 2026 (IR-2025-111) — Official 2026 401(k), catch-up, and IRA contribution limits.
• IRS: Roth Comparison Chart (Roth 401(k), Roth IRA, Traditional 401(k)) — Side-by-side IRS comparison of contribution, distribution, and tax rules.
• IRS: Are Retirement Plan Contributions Subject to FICA, Medicare, or Federal Income Tax? — Authoritative source for the FICA wash: elective deferrals reduce federal income tax wages but not Social Security or Medicare wages.
• Fidelity: New 401(k) Catch-Up Contribution Rules for High Earners — Plain-language overview of the 2026 mandatory Roth catch-up rule for earners above $150,000.
• Schwab: Should You Consider a Roth 401(k)? — Decision framework for choosing between Roth and Traditional contributions.
• SSA: 2026 Social Security Cost-of-Living Adjustment Fact Sheet — Source for the 2026 Social Security wage base of $184,500.