Methodology and Sources
How the paycheck calculators on this site work: IRS Publication 15-T method, 2026 tax figures, state data sources, what is modelled and what is not.
Every calculator on this site uses the same engine and the same 2026 figures. This page explains where the numbers come from and what the estimates leave out.
Sources and Assumptions
This calculator follows the IRS percentage method described in Publication 15-T and the employer rules in Publication 15 (Circular E). The Social Security wage base comes from the Social Security Administration. To tune your own withholding, use the IRS Tax Withholding Estimator and Form W-4.
- Tax year: 2026 federal brackets, standard deductions ($16,100 single, $32,200 married filing jointly, $24,150 head of household), $2,200 child tax credit, $184,500 Social Security wage base.
- What is modelled: federal income tax, Social Security, Medicare (including the 0.9% additional tax), state income tax with a state deduction, employee-paid state payroll programs, pre-tax and after-tax deductions, extra W-4 withholding and a local tax percentage.
- What is not modelled: itemized deductions, other income, non-refundable credits besides the child tax credit, W-4 Step 2 multiple-job adjustments, exact state withholding tables and city taxes (enter a percentage in the local field).
- Privacy: the maths runs in your browser. Nothing you type is sent anywhere.
Last verified: September 2026. State rates, brackets, deductions and employee payroll programs were checked against state revenue and labor department publications and the Tax Foundation 2026 state income tax table. They remain simplified estimates. Confirm with your state revenue department or your employer's payroll team before making financial decisions.
