Methodology & Sources

Every rate, bracket and limit in our tools traces back to a primary government source:

• IRS — Tax inflation adjustments and Revenue Procedures (brackets, standard deduction)
• IRS Rev. Proc. 2025-32 — 2026 inflation-adjusted amounts (applied to all 2026 figures)
• IRS Rev. Proc. 2024-40 — 2025 inflation-adjusted amounts (prior-year baseline)
• Public Law 119-21 (One Big Beautiful Bill Act) — 2025 tax law changes
• IRS Publication 15-T — Federal Income Tax Withholding Methods
• IRS Publication 505 — Tax Withholding and Estimated Tax
• IRS Schedule SE — Self-Employment Tax
• IRS Publication 969 — Health Savings Accounts
• Social Security Administration — Contribution and Benefit Base (wage base)
• US Department of Labor — Overtime under the FLSA
• Federation of Tax Administrators — links to every state revenue department

For state income taxes we read the current-year withholding tables and rate schedules published by each state's department of revenue, including the nine states that levy no tax on wages (Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington and Wyoming).

Our paycheck, take-home pay and salary-after-tax tools follow the same order of operations an employer's payroll system uses:

1. Gross pay is annualized from your salary or hourly rate and pay frequency.
2. Pre-tax deductions (401(k), HSA, Section 125 health premiums) are subtracted where the tool supports them.
3. Federal income tax is computed on taxable income — gross minus the standard deduction for your filing status — using the progressive brackets for the tax year.
4. FICA applies 6.2% Social Security up to the SSA wage base and 1.45% Medicare on all wages, plus the 0.9% Additional Medicare Tax above $200,000 (single).
5. State income tax uses the state's own brackets or flat rate, deduction and personal exemption rules.
6. Net pay is gross pay minus all of the above, then divided by the number of pay periods.

For 1099, freelance, gig-worker and sole-proprietor tools we follow IRS Schedule SE: net earnings are multiplied by 92.35%, then taxed at 15.3% (12.4% Social Security up to the wage base plus 2.9% Medicare). Half of the self-employment tax is deducted before income tax, and the Qualified Business Income deduction is applied where eligible. Quarterly payment tools divide the projected annual liability across the four IRS due dates and apply the safe-harbor rules from Publication 505.

• Federal figures are reviewed every October–November, when the IRS announces inflation adjustments for the next tax year.
• State rates are reviewed each January and whenever a state enacts a mid-year change.
• Where an official figure is not yet published, we label the value as a projection and replace it when the agency releases it.
• Corrections reported through our contact page are reviewed and, if confirmed, published promptly.

Our tools are designed for common situations. They do not model every credit (for example the Earned Income Tax Credit in full detail), itemized deductions, alternative minimum tax, local city or county income taxes in every jurisdiction, multi-state residency, or employer withholding quirks from your W-4. Your actual paycheck or tax bill can differ.

FiscalData.us provides estimates for informational purposes only and is not financial or tax advice.

FiscalData.US is published by DigiConsulting. Calculators and guides are reviewed against the sources above before publication. Found an error? Write to us via the contact page or read more about us.