Learn
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 2026-04-25 · 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
More from /learn/
- Flood zones explained — what AE, X, and VE actually mean
- EPA Radon Zones — what 1, 2, and 3 mean and when you should test
- FBI UCR and NIBRS — what crime statistics actually show (and don't)
- Lead and Copper Rule 2024 — the federal lead-pipe inventory mandate
- AQI explained — what 50, 100, 150 actually mean for your lungs
- School district boundaries — how to confirm yours and why it matters
- Wildfire Hazard Potential — what the USFS scale means and how to defend your home
- EPA SDWIS — how to read drinking-water violations and what they actually mean
- Deed records — what they show and what they don't
- Zoning codes — what R-1, C-2, M-1, MU mean and why your house is one
- Homestead exemption — state-by-state property tax savings
- Reading FBI UCR national crime trends — what 2020–2025 actually shows
- AirNow + wildfire smoke — when AQI is a real-time tool
- Radon and real estate — what disclosure laws and home tests actually require
- Wildfire insurance in 2026 — why premiums spiked and what to do
- NCES Common Core of Data — what district boundaries actually mean for buyers
- EPA SDWIS — reading drinking-water violations without panicking
- FEMA flood zones — AE vs. X vs. VE in plain English
- County assessor data — how millage rates and assessments actually combine