The main difference is when income tax is paid
Traditional deferrals can lower current federal taxable income; Roth deferrals do not. Both remain retirement-plan assets, and payroll taxes, state rules, qualified-distribution requirements, and employer contribution treatment need separate review.
Compare marginal rates, not only account balances
If the tax rate applying to the contribution is higher now than the rate applying to withdrawals, traditional treatment can look favorable; the reverse can favor Roth. Future rates, income, deductions, and law are uncertain, so a split can reduce dependence on one prediction.
Use the same gross contribution in comparisons
An $8,000 traditional contribution and an $8,000 Roth contribution put the same stated amount into the plan but have different current tax effects. A fair after-tax comparison should also account for what happens to any current tax savings.
Example: an $8,000 contribution at a 22% marginal rate
In a simplified federal-only illustration, an $8,000 traditional deferral could reduce current federal income tax by about $1,760 if all $8,000 would otherwise be taxed at 22%. A Roth contribution does not create that current reduction; later distribution taxation differs.
What to check before you decide
- This simplified comparison does not calculate state tax, credits, deductions, future withdrawal rules, or individual eligibility.
- Tax law and plan options can change; confirm the current plan document and IRS guidance.
Sources behind this guide
These official and primary sources let you verify rules, definitions, and terms that may change.
IRS — Roth IRA and designated Roth account differences↗IRS — 2026 retirement plan contribution limits↗U.S. Department of Labor — What you should know about your retirement plan↗