Step-by-Step Breakdown of the Components
A paycheck can include federal income-tax withholding, Social Security, Medicare, state income tax and sometimes local income tax. Benefits and retirement contributions can reduce take-home pay too, although those are deductions rather than taxes.
Federal income-tax withholding depends on the employee's Form W-4 information and the payroll period. The IRS publishes separate withholding methods and tables for 2026, so a weekly paycheck is not calculated in exactly the same way as a monthly paycheck simply by changing the number of checks.
FICA has clearer employee rates. In 2026, Social Security is 6.2% on covered wages up to $184,500, while Medicare is 1.45% on covered wages with no wage-base limit. Additional Medicare withholding of 0.9% begins when an employer pays an employee more than $200,000 in wages during the calendar year.
Taxes, Deductions, and Adjustments
State and local income taxes depend on jurisdiction. That is one reason a paycheck in one state can look very different from an otherwise similar paycheck in another.
Suppose two employees each earn $6,000 gross in a month. If their federal withholding setup is similar but one lives and works in a jurisdiction with additional income tax, their net pay can differ. If one contributes more to a 401(k) or pays more for health insurance, the difference can grow.
This is also why online articles that give a single “tax percentage” can be dangerous for paycheck planning. The percentage may describe one component, one example or one person's effective burden rather than the amount that applies to you.
The better approach is to break the paycheck into pieces:
Estimating and Verifying Your Paycheck
Gross pay → federal withholding → FICA → state/local tax → other deductions → net pay.
Then ask what each line is actually doing.
Remember that withholding is not the same thing as final tax liability. Your tax return determines the federal income tax you ultimately owe based on your full tax situation. Payroll withholding is the mechanism used to collect tax during the year.
If you're estimating a new salary, use a paycheck calculator with the correct state, pay frequency, filing status and deductions. If you're checking an existing paycheck, use the pay stub itself as the primary record and investigate the individual lines when something changes.