Our Methodology
This page explains how PaycheckAfterTax estimates your net (take-home) pay. We aim to be transparent and practical, focusing on the inputs people really use: gross pay, pay frequency, filing status, state, and common pretax/post-tax deductions. The calculator runs entirely in your browser; we do not store your data.
1) Inputs & Scope
- Gross pay amount and pay frequency (weekly, bi-weekly, semi-monthly, monthly).
- Filing status to choose the correct federal baseline.
- State to apply that state’s withholding approach and any statewide payroll taxes, if applicable.
- Pretax deductions such as 401(k) and cafeteria-plan items reduce taxable wages before certain taxes.
- Additional withholding (flat dollar) is modeled as a direct subtraction after standard withholding is computed.
2) Federal Withholding Overview
We approximate federal income-tax withholding using IRS-style bracket logic and pay-period annualization. The tool converts your per-period gross into an annualized figure, estimates federal tax for that annual amount, and then de-annualizes to the current pay period.
Social Security and Medicare (FICA) are computed on wages subject to those taxes. Pretax retirement contributions and cafeteria-plan health premiums typically reduce wages subject to federal income tax; whether they reduce FICA depends on plan type.
3) State Layer
States differ widely. Some have flat systems, some progressive brackets, others rely on federal starting points. Our model applies a per-state routine:
- Annualize per-period wages for the state method.
- Apply that state’s approach to pretax items.
- Compute estimated withholding and de-annualize for the pay period.
4) Deductions & Benefits
- 401(k) contributions are treated as pretax for federal income tax and (in many plans) for state tax; FICA treatment varies by plan rules.
- Health premiums / FSA / HSA are modeled as cafeteria-plan reductions when entered as pretax.
- Additional withholding is subtracted after baseline calculations.
5) Outputs
The calculator shows an estimated net pay for the selected period and a breakdown by component: federal withholding, FICA, state withholding, and the deductions you entered.
6) Important Notes
- This tool provides estimates.
- Local city/county taxes and employer-specific items are out of scope unless you enter them as additional withholding.
- For planning decisions, consult official guidance or a tax professional.
See also: California State Page · Sitemap