United States tax tools

Federal income tax is progressive: each bracket rate applies only to income inside that bracket. Wage earners also pay Social Security up to its annual wage base and Medicare, including Additional Medicare above the applicable threshold.

The paycheck estimator adds a simplified state-income-tax model. It does not reproduce a payroll system or state return, and it excludes local taxes, many credits, special deductions, payroll programs, and phaseouts.

The federal model uses annual arithmetic rather than pay-period withholding tables. A real paycheck can differ because Form W-4 entries, supplemental wages, benefit deductions, payroll timing, and rounding affect withholding. A refund or balance due depends on the complete return, not only salary.

A W-2 employee and a self-employed person have different Social Security and Medicare treatment. The comparison tool models both on the same 2026 single-filer federal basis so the difference is visible without substituting an arbitrary withholding percentage.

Self-employed people may need estimated payments when withholding and credits will not cover the required amount. Form 1040-ES rules, prior-year safe harbor, withholding, and income timing determine actual installments; a four-way split is only a cash-planning view.

Start with the same income period and filing assumptions in every comparison. Do not compare gross contractor receipts with W-2 wages after payroll deductions, or a state estimate with a federal-only result. Record which costs, benefits, credits, and taxes are excluded.

Before making a payment or accepting an offer, replace the planning inputs with current records and official instructions. A transparent scenario helps identify the missing questions; it does not answer facts the calculator never collected.