It’s the most common paycheck surprise there is: you accept a $75,000 offer, divide by 26, and expect $2,884 every two weeks. The number that lands in your account is always smaller — sometimes a lot smaller. Here’s exactly what comes out, and why, using the 2026 numbers this calculator runs on.
FICA — the tax that comes out before anything else
FICA is the combined Social Security and Medicare tax, and it is charged on your gross wages — before your 401(k) contribution reduces anything. That detail surprises people, and it’s worth stating plainly: putting money into a 401(k) lowers your federal income tax but does not lower your FICA.
- Social Security: 6.2% of your gross wages, but only up to the 2026 wage base of $184,500. Earn more than that and the 6.2% stops on the overage.
- Medicare: 1.45% of all of your gross wages — no cap, no ceiling.
- Additional Medicare: an extra 0.9% on wages above $200,000 (single) or $250,000 (married filing jointly).
Federal tax is marginal, not flat
A common fear is that earning more “pushes you into a higher bracket” and costs you money. It doesn’t work that way. The brackets are marginal: only the portion of income inside each bracket is taxed at that bracket’s rate. A single filer with $60,000 of taxable income pays 10% on the first $12,400, 12% on the next chunk up to $50,400, and 22% only on the dollars above that — not 22% on the whole $60,000. The calculator above applies the 2026 brackets exactly this way.
Your taxable income is also smaller than your salary. The standard deduction for 2026 is $16,100 (single) or $32,200 (married filing jointly), and your pre-tax 401(k) and other deductions come off the top first. That’s why two people with the same salary can owe very different amounts.
Why your 401(k) lowers one tax but not the other
Pre-tax 401(k) contributions reduce your federal taxable income, so they shrink the number the brackets are applied to. But FICA is calculated on gross wages before that deduction, so your Social Security and Medicare tax stay the same. Most paycheck calculators bury this; it matters because it changes the real value of contributing more.
Catching up after 50
If you’re in your 40s or 50s and got a late start — after a career break, a divorce, or years of prioritizing the kids — the catch-up rules are built for you. Once you turn 50, the 2026 401(k) catch-up lets you defer an extra $8,000, bringing your total elective deferral to $32,500. Workers aged 60–63 get an even larger catch-up of $11,250, for a total of $35,750. Use the “I’m 50 or older” checkbox above to surface those limits — then set a % that’s ambitious but realistic for your cash flow.
The caveat
This is a simplified, federal-focused estimate. It uses the 2026 brackets, standard deduction, and FICA rules, plus a flat state-rate approximation — it does not model your actual W-4 withholding elections, local or city taxes, credits, or non-deductible benefits. Your real paycheck will differ. It’s an educational tool, not tax advice; for your exact situation, check your pay stub or talk to a tax professional.