Sources we use
We use primary sources only: county appraisal districts and assessors, county treasurers, tax collectors and auditor-controllers, adopted rate orders and tax rate books, state revenue departments and boards of equalization, state statutes, and the U.S. Census Bureau American Community Survey for median taxes and home values. Real estate portals, tax-appeal marketing pages and rate aggregators are never used as sources of fact.
How calculators are checked
Every calculator uses published, standard formulas. The code is covered by automated tests that check known answers (for example, the Cook County Treasurer's sample tax year 2023 bill: a $303,850 home, 10% assessment level, 3.0163 equalization factor and 8.532% local rate gives $7,819.58 before exemptions and $6,283.82 after the homeowner and senior exemptions; our calculator reproduces it to the cent). We show the formula next to each tool so anyone can verify the result by hand.
What we will not publish
- Affiliate links or paid placements for tax appeal firms, lenders or realtors.
- Tax rates from aggregators or real estate portals presented as official.
- Claims we cannot support with a source.
Updates and corrections
Each page shows the date it was last updated. Assessors mail new values each spring, taxing units adopt new rates each fall, and states adjust exemptions through legislation. We refresh the data when the office publishes it and change page dates only when content changes. If you find an error, tell us through the contact page and we will review it and correct it.