To calculate a millage rate, divide the total property tax revenue a jurisdiction needs (the tax levy) by the combined assessed value of all taxable property in that jurisdiction, then multiply by 1,000. The result is expressed in mills, where one mill equals $1 of tax for every $1,000 of assessed value. Once you know the millage rate and your property’s assessed value, your annual tax is a single multiplication.
What a Mill Is
A mill is one-thousandth of a dollar, or $0.001. Applied to property tax, one mill produces $1 of tax for every $1,000 of assessed value. A home assessed at $150,000 in a district with a 1-mill rate owes $150 from that single mill.
Governments use mills instead of percentages because the numbers stay readable. Saying “25 mills” is cleaner than “0.025” or “2.5%.” You will see the same figure written as “25 mills,” “25.000,” or simply “25” when the context is clear. Some jurisdictions call it a levy rate or tax rate; the arithmetic is identical.
The Formula Local Governments Use
Three inputs go into a millage rate:
- The tax levy, meaning the dollar amount the jurisdiction needs to raise from property taxes. Officials start with the total budget for schools, roads, emergency services, and other operations, then subtract non-property-tax revenue like state grants and sales tax. What is left is the levy.
- The total tax base, meaning the combined assessed value of every taxable parcel in the jurisdiction. Property owned by governments, religious organizations, and certain nonprofits is excluded under legal exemptions.
- The conversion: divide the levy by the tax base, then multiply by 1,000.
A worked example: a town needs $5,000,000 in property tax revenue, and the assessed value of taxable property in town totals $250,000,000. Divide $5,000,000 by $250,000,000 to get 0.02. Multiply by 1,000 and the millage rate is 20 mills. Every owner in that jurisdiction then owes $20 per $1,000 of assessed value.
Many states also apply “truth-in-taxation” or rollback rules that force the rate down when rising assessments would otherwise produce more revenue than the prior year. Under those rules, the rate automatically rolls back to hold total revenue steady, and pushing it above the rollback level usually requires a public vote or a supermajority of the governing body.
Turning the Rate Into Your Tax Bill
Once you know the millage rate that applies to your parcel and your net assessed value after any exemptions, the formula is:
Assessed Value ÷ 1,000 × Millage Rate = Annual Property Tax
If your net assessed value is $200,000 and the combined millage rate for all the districts your property sits in is 33 mills, divide $200,000 by 1,000 to get 200, then multiply by 33 for an annual tax of $6,600. You can also multiply first and divide afterward: $200,000 × 33 ÷ 1,000 = $6,600. Same result.
The annual amount is often paid in installments. Some jurisdictions bill twice a year, some quarterly, some in a single lump sum. Due dates vary widely by state, and missing one triggers interest and penalties, so confirm the schedule with your local tax collector.
Why the Rate on Your Bill Is a Sum of Several Rates
Most properties sit inside several overlapping taxing districts at once. Your county levies a rate, your city or town levies another, your school district levies its own, and you may also fall within a fire district, library district, water authority, or other special unit. Each body calculates its rate independently using the same levy-divided-by-base formula.
Your total millage rate is the sum of those individual rates. A typical breakdown might be 8 mills for the county, 5 mills for the city, 18 mills for the school district, and 2 mills for a fire district, adding up to 33 mills. Most bills itemize the districts so you can see where each dollar goes. This is also why two houses of identical value in the same county can carry very different bills if one is inside city limits and the other is not.
Assessed Value Is Not Market Value
The millage rate is only half the equation. The other half is your property’s assessed value, and this is where confusion usually starts. Market value is what a buyer would pay for your home today. Assessed value is a percentage of market value, set by an assessment ratio your jurisdiction applies to residential property. Ratios vary enormously. Some places assess at 100% of market value, others at 40%, and a few as low as 4% to 10%.
A home with a $300,000 market value in a jurisdiction using a 40% ratio has an assessed value of $120,000. The millage rate applies to the $120,000, not the $300,000. Comparing millage rates across jurisdictions without adjusting for the assessment ratio produces misleading conclusions: a 50-mill rate in a place that assesses at 10% of market value is a lighter burden than a 20-mill rate where assessment is at 100%.
Exemptions That Reduce Taxable Value
Most jurisdictions offer exemptions that lower assessed value before the millage rate is applied. The most common is the homestead exemption, which reduces the taxable value of a primary residence by a fixed dollar amount. Sizes vary from a few thousand dollars to well over $100,000, and some places use percentage reductions instead of flat amounts.
Other common exemptions cover senior citizens, disabled veterans, surviving spouses of military members, and agricultural land. These are rarely automatic. You typically apply through your local assessor’s office, and letting an exemption lapse can push your bill up sharply the following year. Your annual notice of valuation lists your assessed value and the exemptions currently applied. If an exemption you filed for is missing, contact the assessor before the tax bill arrives.
A Full Worked Example
Put every piece together with a realistic scenario. Your home has a market value of $350,000, your jurisdiction uses a 40% assessment ratio, you receive a $25,000 homestead exemption, and the combined millage rate across your county, city, and school district is 45 mills.
- Step 1 — Assessed value: $350,000 × 0.40 = $140,000
- Step 2 — Apply the exemption: $140,000 − $25,000 = $115,000 net taxable value
- Step 3 — Calculate the tax: $115,000 ÷ 1,000 × 45 = $5,175 annual property tax
If the same property sat outside the city limits and only owed county and school taxes at a combined 38 mills, the bill would be $115,000 ÷ 1,000 × 38 = $4,370. An $805 gap on identical parcels shows why the districts you belong to matter as much as the rate itself. Confirm which districts cover your parcel before assuming a published rate applies to you.
Where to Find Your Numbers
Two figures drive the whole calculation. Here is where each comes from:
- Your assessed value and current exemptions appear on the annual notice of valuation from the assessor’s office. Most counties also publish assessment data through an online portal that lets you look up any parcel by address or parcel number.
- Your millage rate is itemized on your property tax bill by district. Outside of billing season, the county auditor or tax commissioner’s website usually posts the current certified rates, and some states publish statewide tables of mill rates by municipality through their department of revenue.
If you are estimating taxes on a home you are considering buying, the listing agent or county website can supply last year’s tax bill and the current rates. A sale can trigger a reassessment, though, so the seller’s bill is a starting point rather than a guarantee of what you will owe.