Traditional 401(k) vs take-home
Traditional elective deferrals reduce federal and state taxable wages but do not reduce FICA (Social Security and Medicare). Your paycheck shrinks by the contribution, but tax savings are income-tax only.
Roth 401(k)
Roth deferrals are post-tax: they do not reduce income tax or FICA. They only reduce net pay by the contribution amount.
Compare scenarios
Use the US paycheck calculator’s optional 401(k) fields and “Compare 401(k) scenarios” to see how raising contributions changes net pay and tax.
Frequently asked questions
What is the 2026 elective deferral limit?
Generally $23,500, plus catch-up contributions if age 50+ — confirm IRS limits for your plan.
Does 401(k) reduce Social Security tax?
No — traditional 401(k) does not reduce FICA.
Is HSA different?
Yes — HSA / §125 cafeteria contributions typically reduce income tax and FICA.
Is this advice?
No. Educational estimates only.