The Basic Formula: Assessed Value × Millage Rate ÷ 1,000
Property tax is calculated by multiplying your property's assessed value by the millage rate, then dividing by 1,000. A millage rate of 25 mills means $25 in tax per $1,000 of assessed value. So if your home is assessed at $300,000 and your millage rate is 25 mills, your annual property tax is ($300,000 × 25) ÷ 1,000 = $7,500.
The millage rate is set by your local government — usually your county assessor's office or a county commission — and changes each year based on the total revenue the county needs to collect. Your assessed value is determined by your county assessor and is typically a percentage of your home's market value, not the price you paid for it.
Both numbers are public information. You can find your assessed value on your property tax bill or by contacting your county assessor's office directly. The millage rate is published by your county and is often posted on the assessor's website or the county commission's website.
Key Takeaways
- The calculation is: (Assessed Value × Millage Rate) ÷ 1,000 = Annual Property Tax.
- A millage rate of 20 mills means you pay $20 in tax for every $1,000 your property is assessed at.
- Your assessed value is usually 80 to 100 percent of your home's market value, depending on your state.
- Both your assessed value and your millage rate are public records you can find through your county assessor or tax collector.
- The millage rate changes yearly; your tax bill will change even if your home's value stays the same.
Understanding Assessed Value
Your assessed value is not what you paid for your home or what it would sell for today. It is the value your county assessor assigns to your property for tax purposes. In most states, this is a percentage of the property's market value — often 80 to 100 percent, depending on state law.
The assessor determines this value by looking at recent sales of similar homes in your area, the condition of your property, and any improvements you have made. You will find your assessed value on your property tax bill, your county assessor's website, or by calling the assessor's office directly. Some counties call it "assessed value"; others call it "taxable value" or "appraised value."
Your assessed value can change year to year, even if you have not made any changes to your home. If your neighborhood's property values rise, your assessed value may rise too. If you believe your assessed value is too high, most counties allow you to file a formal challenge called an assessment appeal or property tax appeal — the process and deadline vary by state.
What the Millage Rate Means
The millage rate is expressed in mills. One mill equals one-tenth of one cent, or $0.001. A millage rate of 20 mills means $20 per $1,000 of assessed value. A rate of 35 mills means $35 per $1,000.
Your county sets the millage rate each year based on how much money it needs to collect for schools, roads, emergency services, and other public services. If the county needs more revenue, the millage rate goes up. If it needs less, the rate may go down. The rate is published before the tax year begins and is available on your county commission's website or through your tax collector's office.
Some counties have a single millage rate that applies to all residential properties. Others have different rates for different types of property — residential, commercial, agricultural — or different rates for different districts within the county. Check your tax bill or your county's website to find the exact rate that applies to your property.
Step-by-Step Calculation Example
Here is a worked example using real numbers:
| Step | Your Numbers | Example |
| 1. Find your assessed value | Check your tax bill or county assessor website | $250,000 |
| 2. Find your millage rate | Check your tax bill or county website | 18 mills |
| 3. Multiply assessed value by millage rate | $250,000 × 18 | $4,500,000 |
| 4. Divide by 1,000 | $4,500,000 ÷ 1,000 | $4,500 |
| 5. Result is your annual property tax | $4,500 |
Your actual tax bill may include additional charges such as school district taxes, special assessment districts, or county bonds. These are calculated separately and added to your base property tax. Your tax bill will show all of these line by line.
Where to Find Your Assessed Value and Millage Rate
Your property tax bill is the easiest place to find both numbers. The bill lists your assessed value and the millage rate applied to it, usually near the top or in a summary section. If you do not have your bill, you can find both numbers online.
Your county assessor's office maintains a searchable database of all properties in the county, including assessed values. Search by your address or parcel number — both are public records. The assessor's website also usually lists the current millage rate, or you can call the office directly.
Your county tax collector or county commission website will also post the millage rate for the current tax year. Some counties publish it in the local newspaper before the tax year begins. If you cannot find it online, call your county assessor or tax collector's office — they can give you the rate over the phone in a few minutes.
Why Your Tax Changes Year to Year
Even if your home's market value stays the same, your property tax can change because the millage rate changes. If your county needs more money for schools or infrastructure, the millage rate goes up and your tax bill goes up, even though your assessed value did not move.
Your assessed value can also change independently of the millage rate. If your county reassesses all properties and your home's assessed value increases, your tax bill will increase even if the millage rate stays flat. Conversely, if you make a major repair or improvement to your home, the assessor may increase your assessed value, raising your tax bill.
Some states have caps on how much the assessed value can increase in a single year, or on how much the millage rate can rise. Check your state's property tax laws or ask your county assessor whether such caps apply to your property.
Frequently Asked Questions
Can I calculate my property tax if I just know my home's market value?
Not directly. You need your assessed value, which is usually 80 to 100 percent of market value but varies by state and county. Look up your assessed value on your county assessor's website or tax bill, then use that number in the calculation.
What if my county uses a different term instead of "millage rate"?
Some counties call it the tax rate, levy rate, or mill rate. The concept is the same: it is the amount of tax per $1,000 of assessed value. Check your tax bill or county website for the exact term your county uses.
Does the calculation include school taxes and special districts?
The basic formula gives you the general property tax. Your actual bill usually includes separate line items for school district taxes, fire district taxes, and other special assessments, each with its own millage rate. Add all of these together to get your total tax bill.
What should I do if I think my assessed value is wrong?
Contact your county assessor's office and ask about filing an assessment appeal or property tax protest. Most counties have a deadline — often 30 to 60 days after you receive your tax bill — and require you to submit evidence such as recent appraisals or comparable sales in your area.
How often does the millage rate change?
The millage rate is set once per year, usually before the tax year begins. Your county publishes the new rate in advance, so you can see what your tax bill will be before you receive it. Some counties allow the rate to change mid-year if an emergency arises, but this is uncommon.