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Property tax millage — what 'mill' means and how your bill is computed
Property tax math looks complex but reduces to one formula: assessed value × millage rate ÷ 1,000 = annual tax. The variables are all set at the county or city level — every step has its own rules.
Published 2026-04-25 · Last reviewed 2026-07-03 · methodology
What is a 'mill'?
A mill is one one-thousandth of a dollar. A 25-mill rate means $25 of property tax for every $1,000 of assessed value. So a home assessed at $300,000 in a 25-mill county pays $300,000 × 25 ÷ 1,000 = $7,500/year.
Total millage is usually a stack of jurisdictions: county general fund + school district + city + special assessments. Each line item sets its own rate; the bill sums them.
Assessed value vs. market value
Most counties don't tax the market value directly — they tax an 'assessed value' that's a fraction. Common assessment ratios: 100% (Florida), 50% (Michigan), 19% (Mississippi). The county publishes its assessment ratio annually.
Some states cap how fast assessed value can grow year-over-year (California Prop 13: 2% annual cap; Texas: 10% cap on homestead). These caps create wildly different effective tax rates between long-time owners and new buyers in the same neighborhood.
Homestead and senior exemptions
Most states offer a homestead exemption that reduces the assessed value for owner-occupied primary residences. Florida exempts $50,000; Texas $40,000; many others $20,000–$30,000.
Senior, disability, and veteran exemptions stack on top in many jurisdictions. Always file the exemption forms with the assessor — they're not automatic.
Why neighbors pay different amounts
Two identical homes side-by-side can have wildly different tax bills due to: different assessment dates (Prop-13 effect), different homestead status, different mortgage exemptions, different special assessments (e.g., a Community Facilities District for a new school).
zipradar shows the county millage rate. For your specific home, the assessor's portal is the source of truth — the link is on every county page.
Related zipradar topics
Glossary terms used here
Related guides
- County assessor data — how millage rates and assessments actually combine
- Deed records — what they show and what they don't
- Homestead exemption — state-by-state property tax savings
- Zoning codes — what R-1, C-2, M-1, MU mean and why your house is one
- Abandoned property + tax sales — buying via county auction
- Buying a foreclosure or short sale — what's different, what's risky, and what you need to verify