Data sources
Every number on KeepWage traces back to a primary source — the IRS or a state revenue department, never another calculator site. This page lists them all. Tax data last verified June 8, 2026. See how we calculate for the method, or report an error if a figure looks wrong.
Federal tax data
- IRS Rev. Proc. 2025-32 — 2026 federal income tax brackets and standard deduction
- IRS Topic 751 — Social Security & Medicare (FICA) withholding rates
- IRS Topic 560 — 0.9% Additional Medicare Tax thresholds
- SSA — contribution & benefit base — Social Security wage base ($184,500 for 2026)
Other federal references
- IRS Topic 554 — Self-employment (SECA) tax
- IRS Publication 15 — 22% federal supplemental-wage withholding (bonuses)
- Tax Foundation — 2026 state sales tax rates — Average combined state + local sales tax rates
- U.S. Census Bureau P60-282 — Income in the United States (individual earnings distribution)
- SSA wage statistics — National wage distribution by earnings level
State tax authorities (all 50 states)
State brackets, standard deductions, credits and payroll levies come from each state's own revenue department. Each engine is validated against published worked examples before it ships.
- Alabama: Alabama Department of Revenue
- Alaska: Alaska Department of Revenue, Tax Division
- Arizona: Arizona Department of Revenue
- Arkansas: Arkansas Department of Finance and Administration
- California: California Franchise Tax Board
- Colorado: Colorado Department of Revenue
- Connecticut: Connecticut Department of Revenue Services
- Delaware: Delaware Division of Revenue
- Florida: Florida Department of Revenue
- Georgia: Georgia Department of Revenue
- Hawaii: Hawaii Department of Taxation
- Idaho: Idaho State Tax Commission
- Illinois: Illinois Department of Revenue
- Indiana: Indiana Department of Revenue
- Iowa: Iowa Department of Revenue
- Kansas: Kansas Department of Revenue
- Kentucky: Kentucky Department of Revenue
- Louisiana: Louisiana Department of Revenue
- Maine: Maine Revenue Services
- Maryland: Comptroller of Maryland
- Massachusetts: Massachusetts Department of Revenue
- Michigan: Michigan Department of Treasury
- Minnesota: Minnesota Department of Revenue
- Mississippi: Mississippi Department of Revenue
- Missouri: Missouri Department of Revenue
- Montana: Montana Department of Revenue
- Nebraska: Nebraska Department of Revenue
- Nevada: Nevada Department of Taxation
- New Hampshire: New Hampshire Department of Revenue Administration
- New Jersey: New Jersey Division of Taxation
- New Mexico: New Mexico Taxation and Revenue Department
- New York: New York State Department of Taxation and Finance
- North Carolina: North Carolina Department of Revenue
- North Dakota: North Dakota Office of State Tax Commissioner
- Ohio: Ohio Department of Taxation
- Oklahoma: Oklahoma Tax Commission
- Oregon: Oregon Department of Revenue
- Pennsylvania: Pennsylvania Department of Revenue
- Rhode Island: Rhode Island Division of Taxation
- South Carolina: South Carolina Department of Revenue
- South Dakota: South Dakota Department of Revenue
- Tennessee: Tennessee Department of Revenue
- Texas: Texas Comptroller of Public Accounts
- Utah: Utah State Tax Commission
- Vermont: Vermont Department of Taxes
- Virginia: Virginia Department of Taxation
- Washington: Washington Department of Revenue
- West Virginia: West Virginia Tax Division
- Wisconsin: Wisconsin Department of Revenue
- Wyoming: Wyoming Department of Revenue
Data changelog
When the tax data behind the calculators changes, it's recorded here.
- 2026-06-12Published this source list; added per-page citations and visible verification dates site-wide.
- 2026-06-08Expanded state coverage to all 50 states. Every state engine validated against published worked examples ($50k/$100k single filer) from its revenue department before shipping.
- 2026-06-07Launched with 2026 federal brackets (IRS Rev. Proc. 2025-32), FICA rates, and California, New York, Texas and Florida state engines.
These are estimates for general information only and are not tax advice.