How we calculate your paycheck

Every figure on this site comes from a single calculation engine that uses official 2026 data. This page explains each step and links to the sources.

Federal income tax withholding

We follow the Annual Percentage Method in IRS Publication 15-T (2026), Worksheet 1A, for a 2020-or-later Form W-4:

1. Taxable wages for the pay period are multiplied by the number of pay periods in a year (52, 26, 24 or 12).
2. If the Step 2 “two jobs” box is not checked, $8,600 is subtracted ($12,900 for married filing jointly).
3. The result is run through the 2026 withholding rate schedule for your filing status and divided back by the number of pay periods.
4. Any dependents credit from Step 3 of the W-4 is subtracted, spread across the year.

Our automated tests compare the engine against every row of the IRS 2026 biweekly wage bracket tables for all three filing statuses, with and without the Step 2 box: all 1,068 official values match to the dollar.

Social Security and Medicare (FICA)

• Social Security: 6.2% of wages up to the 2026 wage base of $184,500 (maximum $11,439), per the Social Security Administration.
• Medicare: 1.45% of all wages, plus the 0.9% Additional Medicare Tax that employers withhold on wages above $200,000.

Pre-tax deductions

Traditional 401(k) contributions reduce the wages subject to federal and state income tax but not FICA. Health insurance premiums and HSA contributions made through a Section 125 cafeteria plan reduce both.

State income tax

For each state we apply the 2026 brackets, standard deduction and personal exemptions in effect on January 1, 2026, to estimate the year’s state income tax and spread it evenly across your paychecks. Employers use each state’s own withholding formula, so a real paycheck can differ by a few dollars. Local income taxes (for example New York City, Pennsylvania local earned income tax or Ohio municipal taxes) and state payroll programs such as disability insurance are noted on each state page and are not yet included in the totals.

Sources

• IRS Publication 15-T (2026), Federal Income Tax Withholding Methods
• IRS Revenue Procedure 2025-32 (2026 inflation adjustments)
• Social Security Administration, Contribution and Benefit Base
• Tax Foundation, 2026 State Income Tax Rates and Brackets

Limits

Results are estimates for planning. They are not tax, legal or payroll advice. If something looks wrong, please tell us and we will check it against the source.

Last reviewed November 2026.