Calculation methodology
Tax year: 2026. Federal source review: 2026-09-23. These tools estimate annual tax liability and available cash, not actual paycheck withholding or a tax return.
Income and costs
Income per pay period is multiplied by 52 for weekly pay, 26 for biweekly pay, 12 for monthly pay, or 1 for yearly pay. Hourly and day-rate tools model contractors. All expense, insurance and retirement entries are annual amounts. Take-home pay subtracts those cash costs as well as modeled taxes, with a minimum displayed value of zero.
Federal income tax
The model uses 2026 progressive brackets and the basic standard deduction: $16,100 single, $32,200 married filing jointly, or $24,150 head of household. It subtracts entered eligible pre-tax costs and, for contractors, half of regular self-employment tax before applying the brackets.
IRS Revenue Procedure 2025-32, section 4
Social Security and Medicare
For contractors, regular self-employment tax uses 92.35% of positive profit, a $400 net-earnings threshold, 12.4% Social Security up to the $184,500 earnings base, and 2.9% Medicare. Employees pay 6.2% Social Security up to the same cap and 1.45% Medicare. Additional Medicare Tax is 0.9% above $200,000, or $250,000 for married joint filers; it is not included in the deductible half of self-employment tax.
W-2 health premiums are assumed to qualify for pre-tax treatment under a cafeteria plan. Retirement contributions reduce income tax but not FICA. The model assumes one earner and one income type; combined W-2 and self-employment income and a spouse’s earnings are not modeled. The Social Security cap applies per worker, so do not combine two workers’ wages in one input.
SSA contribution and benefit base · IRS self-employment tax
State model limitations
The 15 flat-tax states use each state’s verified current statutory flat rate. The 9 states with no tax on wage or business income (including Washington, which taxes only capital gains) are 0%. The 27 progressive-bracket states (plus DC) use the verified marginal rate that applies at $75,000 of state taxable income as a single representative figure — not the top bracket rate, and not a full model of that state’s bracket schedule. All rates were checked against official state and Tax Foundation sources on 2026-09-23. Applied to federal taxable income, without state-specific deductions, additional brackets or local taxes. Do not treat the displayed percentages as current tax law. Use the official revenue agency links in the state directory to check your obligations. A zero percentage does not rule out business, local, capital gains or other taxes.
What is excluded
The model excludes tax credits, qualified business income deductions, itemized deductions, AMT, investment taxes, age-related or special deductions, and validation of retirement/insurance eligibility or contribution limits. Additional deductions, if supplied programmatically, are treated as eligible pre-tax cash costs. Benefits and employer contributions are not valued in the comparison.
Tax reserves
The monthly reserve is estimated annual taxes divided by 12, with a 10% buffer. It is not a quarterly payment schedule or an IRS safe-harbor calculation. Tax law and your circumstances determine what you actually owe.
Public dataset
Download the JSON dataset. It is generated from the same constants as the calculators. A null upper bracket limit means there is no upper limit. State values are explicitly marked as illustrative assumptions.