How Your Paycheck Actually Works
You look at your offer letter, see a number, and then your first paycheck arrives showing something noticeably smaller. This guide walks through exactly where the difference goes — line by line, the same way our paycheck calculator breaks it down.
1. Gross pay vs. net pay
Gross pay is your total earnings before anything is taken out — your salary divided by the number of pay periods, or your hourly rate times hours worked. Net pay (also called take-home pay) is what actually lands in your bank account after taxes and deductions.
The gap between the two is made up of a predictable set of pieces: federal tax, state tax (in most states), FICA taxes, and whatever pre-tax or post-tax deductions you've elected. None of these are arbitrary — each one follows a specific formula, which is exactly what a calculator like this one models.
2. Federal income tax: how brackets actually work
The most common misunderstanding about federal tax is thinking that landing in a higher bracket means all of your income is taxed at that rate. It doesn't. The U.S. uses a marginal bracket system — each dollar is taxed at the rate for the bracket it falls into, not your whole income at your top rate.
Example: if the first $11,925 of income is taxed at 10%, and the next chunk up to $48,475 is taxed at 12%, someone earning $40,000 doesn't pay 12% on all $40,000. They pay 10% on the first $11,925, and 12% only on the income above that. Your effective tax rate — what you actually pay as a share of total income — is always lower than your top marginal bracket.
Before brackets are even applied, the IRS also allows a standard deduction — a chunk of income that isn't taxed at all — which varies by filing status (single, married filing jointly, head of household, etc.). This is why filing status changes your paycheck: it shifts both your deduction amount and where the bracket thresholds fall.
Why your bonus feels like it's taxed more
Bonuses and commissions are usually withheld at a flat 22% federal supplemental rate, regardless of your actual bracket. It's a withholding shortcut, not a separate tax — if you overpaid, the excess comes back when you file your return.
3. FICA: Social Security and Medicare
FICA taxes fund Social Security and Medicare, and they're separate from income tax entirely — flat percentages applied to (almost) all wages, split between employee and employer.
| Tax | Employee rate | Notes |
|---|---|---|
| Social Security | 6.2% | Only on wages up to the annual wage base ($184,500 for 2026) — earnings above that are not taxed for Social Security. |
| Medicare | 1.45% | Applies to all wages, no cap. |
| Additional Medicare | 0.9% | Kicks in above IRS income thresholds (varies by filing status). |
Unlike federal income tax, FICA isn't affected by your deductions or filing status in the same way — it's calculated straight off your gross wages (with a couple of narrow exceptions for certain pre-tax benefits).
4. State and local tax
This is where paychecks diverge the most from state to state. Broadly, states fall into a few categories:
- No income tax — states like Texas, Florida, and Washington don't tax wages at all, so your take-home pay is higher for the same gross salary.
- Flat tax — a single percentage applied to all income, regardless of how much you earn.
- Progressive brackets — similar to the federal system, with marginal rates that increase at higher income levels.
On top of state tax, some cities and counties add their own local income tax — New York City and Philadelphia are well-known examples. If you live in one of these, it shows up as a separate line on your stub, on top of state tax.
5. Pre-tax vs. post-tax deductions
This is one of the more impactful choices you actually control on a paycheck, and it's often misunderstood.
Pre-tax deductions
Contributions like a Traditional 401(k) or HSA are subtracted from your gross pay before federal (and usually state) tax is calculated. That lowers your taxable income for the period — you pay less tax now, but Traditional 401(k) withdrawals are taxed later in retirement.
Post-tax deductions
A Roth 401(k) is withheld after tax is calculated — you pay tax on that money now, but qualified withdrawals in retirement are tax-free. Since it doesn't reduce your taxable wages today, choosing Roth over Traditional will show a smaller take-home paycheck for the same contribution amount, even though the money is going to the same kind of account.
Neither approach is universally "better" — it depends on whether you expect to be in a higher or lower tax bracket in retirement than you are today. Toggling between Traditional and Roth in the calculator is a quick way to see the actual dollar difference on your next paycheck.
6. Why your actual paycheck won't match any calculator exactly
Every paycheck calculator — including this one — uses simplified versions of federal and state tax rules to give a close, useful estimate. Your actual employer withholds based on the specific elections on your W-4, your exact benefit costs, and your state or locality's official withholding tables, which can include nuances a general calculator doesn't capture. Treat these numbers as a strong planning estimate, not a guaranteed match to your exact stub.
Frequently asked questions
Why did my paycheck change even though my salary didn't?
Usually one of: a new tax year with updated brackets, a change to your benefit elections (401k %, HSA contribution), a filing status change, or you crossed a threshold like the Social Security wage base or Additional Medicare limit partway through the year.
Does claiming more dependents on my W-4 increase my paycheck?
Yes — claiming dependents reduces the amount withheld from each paycheck, which increases your take-home pay throughout the year. It doesn't change your total tax bill, just how much is withheld upfront versus reconciled when you file.
Is overtime taxed at a higher rate?
No — overtime pay is taxed the same as regular wages. It can feel like it's taxed more because a bigger paycheck can temporarily push more of that check's income into a higher withholding bracket for that pay period, but your annual tax rate is based on total yearly income, not any single check.
What's the difference between a tax deduction and a tax credit?
A deduction (like the standard deduction or a 401k contribution) reduces the income that gets taxed. A credit reduces your tax bill directly, dollar for dollar, after tax is calculated — which generally makes credits more valuable per dollar than deductions.
Want to see these numbers with your own pay, state, and deductions? Try the calculator →