Our data sources
Every number on aftrtax comes from published 2026 tax rules. These are the agencies and documents we use, with links to the official sources.
Federal
- Internal Revenue Service — Revenue Procedure 2025-32: 2026 federal tax brackets and standard deductions; the 0.9% Additional Medicare Tax thresholds.
- Social Security Administration — the 2026 Social Security wage base of $184,500 and the 6.2% / 1.45% payroll tax rates.
State income tax
Our state figures start from Tax Foundation's 2026 table of state income tax rates, which is compiled from each state's own publications. We then check every state against its tax agency's 2026 publications, withholding guides and laws passed during 2026, and correct anything that has changed. Where an agency had not yet published a 2026 figure, we use its latest published figure. These are the agencies we check against:
Disability and paid leave insurance
- California Employment Development Department — State Disability Insurance (SDI).
- Colorado FAMLI, Connecticut Paid Leave, Delaware Department of Labor, Hawaii Disability Compensation Division, Maine Paid Family and Medical Leave, Massachusetts PFML, Minnesota Paid Leave.
- New Jersey Department of Labor (TDI and FLI), New York Paid Family Leave, Paid Leave Oregon, Rhode Island Department of Labor and Training.
- Washington Paid Family and Medical Leave and WA Cares Fund.
Local income tax
- New York City and Yonkers: New York State Department of Taxation and Finance.
- Philadelphia: City of Philadelphia Wage Tax.
- Indiana counties: Indiana Department of Revenue, Departmental Notice #1.
- Ohio: school district rates from the Ohio Department of Taxation; city rates from the Regional Income Tax Agency (RITA) member directory and city tax offices.
- Michigan: city rates and exemptions as published by the City of Grand Rapids Income Tax Department.
- Kentucky: Louisville Metro Revenue Commission, Lexington-Fayette Urban County Government; other city rates from published compilations of local occupational tax rates.
Cross-checks
We compare our figures with Tax Foundation's state income tax tables, state tax alerts from EY and other tax firms, and the payroll bulletins of the USDA National Finance Center, which publish each state's withholding changes.
How we keep it current
We check for federal and state tax changes every week and re-verify every state against its tax agency on a rolling schedule. When a rule changes, the calculator and every page are updated. See How we calculate for exactly what the calculator includes and leaves out.
aftrtax is independent and is not affiliated with or endorsed by the IRS, the Social Security Administration or any state or local tax agency.
Last updated October 23, 2026