401k paycheck calculator
Putting money in a 401(k) costs you less than the amount you contribute, but more than most calculators suggest. Social Security and Medicare are still charged on every dollar you defer. Enter your salary to see the real number.
Social Security and Medicare are charged on your full salary, so $298 of what you defer is still taken. Texas has no wage income tax, so the state part is exact.
Your paycheck, side by side
The same salary, once without a contribution and once with. Watch the Social Security and Medicare rows.
What your 401(k) never saves you
This is the part the usual shortcut leaves out.
Here the shortcut is $168 too low, because Social Security and Medicare are still charged on the pay you defer.
The IRS puts it plainly. Elective deferrals are not subject to federal income tax withholding when you make them, but they are included as wages subject to Social Security, Medicare and unemployment tax. So 7.65 cents of every dollar you defer is taken anyway, at any salary below the Social Security wage base. The FICA line in the table above does not move.
The state rule most people have backwards
Two states are usually named here. One of them is the wrong way round.
Pennsylvania treats the money as pay the moment you earn it. Its Personal Income Tax Guide lists employee contributions to a qualified deferred compensation plan under income always taxable as Pennsylvania compensation, so a Pennsylvania 401(k) saves you no state tax at all. This calculator applies that rule rather than only mentioning it.
New Jersey is the one people get wrong. It does exclude 401(k) contributions from New Jersey wages. What New Jersey taxes is contributions to 403(b), 457, 409A, 414(h), SEP and IRA plans. If you have a 403(b) rather than a 401(k), the state saving you are counting on is not there.
Only Pennsylvania and New Jersey have been checked against their own revenue departments. Every other state is applied as following the federal treatment, and this page does not claim more than that.
What each contribution level costs
Per paycheck, on the salary and state above.
| You put in | Per paycheck | Real cost | Saving rate |
|---|---|---|---|
| 3% | $75 | $66 | 12.0% |
| 6% | $150 | $132 | 12.0% |
| 10% | $250 | $220 | 12.0% |
| 15% | $375 | $330 | 12.0% |
The 2026 limit on what you can defer is $24,500, so a high percentage on a high salary stops there.
Common questions
Does a 401(k) reduce my Social Security tax
No. It reduces income tax only. Social Security and Medicare are charged on your full salary including the part you defer, which is why the real cost of contributing is higher than a flat tax-rate estimate suggests.
Is a Roth 401(k) worth more or less right now
Right now it costs more. A Roth contribution comes out of pay you have already paid income tax on, so your take-home drops by the full amount you put in. You buy tax-free withdrawals later instead of a deduction today.
Should I contribute enough to get the full match
The match is the one part of this that is not a trade-off. It is money your employer adds that never comes out of your take-home, so the contribution that earns the full match is the cheapest money you will put in.
What this leaves out
The result is an estimate, not tax advice. It covers a traditional pre-tax deferral and does not model catch-up contributions, after-tax or mega-backdoor contributions, HSA or other pre-tax deductions, local and city taxes, or credits. For states with graduated brackets the state portion is carried as one labelled effective rate, so treat that part as an approximation and the federal, Social Security and Medicare parts as exact.