Every calculator here follows the same three rules. They are the whole product.
1. The number comes from the source, not from another website
State income tax figures are read off the state's own revenue department — its withholding guide, its rate schedule, or the text of the bill that changed it. Federal figures come from the IRS inflation adjustments and Publication 15-T. The Social Security wage base comes from the Social Security Administration.
This matters more than it sounds. When this site was built, the national table most free calculators rely on had Georgia at 5.19%. Georgia's own Department of Revenue said 4.99%; the legislature had cut it in May and backdated it to January. Checking all fifty-one jurisdictions against their own departments turned up fifteen wrong figures.
2. Every page shows its working and its date
Each state page names the document it was checked against, links to it, and prints the date of the check. Under the result, the arithmetic is written out: which deductions came off, what was left, and what rate was applied to it. If you disagree with the answer you can see exactly where we differ.
3. Figures are re-checked on a schedule
Weekly from March to June, which is when state legislatures sit and when every rate change of 2026 happened. Monthly for the rest of the year. Each December and January the whole set is re-verified, because states re-index their brackets for the new tax year all at once.
When a figure moves, the page is updated and the change is noted. When nothing has moved, the date stays where it is. A page that quietly refreshes its date without a real change is lying to you in a small way, and we would rather not.
What is deliberately not included
Local city, county and school-district income taxes. State disability and paid-family-leave contributions. Garnishments and child support. The flat supplemental rate applied to bonuses. Itemised deductions above the standard deduction. Credits claimed on your annual return. Multi-state withholding when you live and work in different states.
These are left out because getting them right requires knowing your exact municipality and circumstances. Where one of them is likely to affect you, the relevant page says so.
Accuracy, and its limits
These are estimates for planning. Your employer uses the IRS percentage-method tables, which round at each step, so a few dollars of difference is normal and not an error. A difference of more than that usually means a deduction we do not model — start with the list above.
Nothing here is tax advice. See the terms for the full position, and about for who is writing this.