From gross to take-home: the four deductions
A US paycheck reads as a subtraction chain. Starting from gross pay — your contractual salary, divided by your pay frequency — four families of withholding reduce it to the deposit that lands in your account:
- Pre-tax deductions — 401(k) deferrals, health insurance premiums, FSA/HSA contributions. They shrink your taxable wages before income tax is computed (but not your FICA wages).
- FICA — Social Security and Medicare payroll taxes, a flat 7.65% on most paychecks.
- Federal income tax — computed on taxable income after the standard deduction, using progressive brackets from 10% to 37%.
- State income tax and state payroll taxes — zero in nine states, meaningful in most others.
On a $75,000 salary, single filer in California, the NetWage engine computes $57,689.93 of annual take-home — $4,807.49 per month, roughly $2,218.84 per biweekly check. The $17,310.07 withheld represents an effective 23.08% of gross. This matches the $75,000 after tax page, pre-computed with the same parameters.
What each withholding line is
| Line (75,000 $/yr, CA, single) | Rate | Amount |
|---|---|---|
| Social Security (OASDI, ≤ 184,500 $) | 6.20% | $4,650.00 |
| Medicare | 1.45% | $1,087.50 |
| Federal income tax (single, taxable 58,900 $) | 13.02% | $7,670.00 |
| CA state income tax | 4.22% | $2,927.57 |
| California SDI | 1.30% | $975.00 |
Social Security ($4,650.00) and Medicare ($1,087.50) are flat payroll taxes — the FICA guide covers their caps and the employer match you never see. Federal income tax ($7,670.00) is progressive: here it runs at 13.02% of the taxable income, i.e. gross minus the $16,100 standard deduction for a single filer. California then adds its own income tax plus SDI, a state disability insurance premium that has had no wage cap since 2024.
Reading the stub itself
Beyond the current-period column, check the YTD (year-to-date) figures: they are what your W-2 reconciles against in January. Three boxes matter most — W-2 Box 1 (federal taxable wages, lower than gross if you defer into a 401(k) or pay premiums pre-tax), Box 3 (Social Security wages, which ignores pre-tax deductions and stops at the annual wage base), and Box 5 (Medicare wages, uncapped). If Box 1 differs from your gross, the difference is almost always your pre-tax elections.
Also note the employer-paid section: your employer pays a matching 7.65% FICA on top of your salary — it never appears as a deduction because it was never part of your gross.
Annual salary vs per-check amount
Employers quote salaries annually but pay on a frequency — weekly (52 checks), biweekly (26), semimonthly (24) or monthly (12). The annual withholding total is the same; only its split changes. Biweekly and semimonthly are often confused: 26 checks of $2,218.84 versus 24 checks of $2,403.75 on our example — the semimonthly check is larger, but there are two fewer per year. Months with three biweekly paychecks are a quirk of the calendar, not a bonus.
One more distinction useful on any stub: statutory deductions (FICA, income tax withholding — required by law) versus voluntary ones (401(k), premiums, union dues, wage garnishments aside). If your net looks wrong, checking the voluntary lines first is usually fastest.
Why your stub may differ from a calculator
The most common gaps between a generic estimate and a real paycheck: 401(k) and health premiums (your elections are employer-specific), local income taxes (New York City adds its own, as do Detroit, San Francisco and others), and refundable credits or itemized deductions — those only settle when you file. Payroll frequency also shifts the per-check amount without changing the annual result: 26 biweekly checks or 24 semimonthly ones split the same take-home differently. The exact scope of the engine is documented on the methodology page; try your own gross, filing status and state in the salary calculator. Indicative estimate computed with the official parameters in force — not a pay slip, and not tax or legal advice.