Estimate your annual property tax bill from your home's value, assessment ratio and local mill rate.
The calculator follows the mill-rate method that many local governments use: take the property's market or appraised value, apply the assessment ratio to get assessed value, subtract any fixed-dollar exemption to get taxable assessed value, then multiply by the mill rate. In one line: (value x assessment ratio - exemption) / 1,000 x mill rate = estimated annual tax.
The math is simple. The hard part is knowing what each number means where you live, because assessors, school boards and city councils use different words for similar ideas. Where your bill uses a mill rate, this tool can estimate the base tax from the numbers printed on your assessment notice or tax bill. Where your area works differently, for example with percentage exemptions, tax credits or caps on yearly increases, the estimate will be rougher, and the calculator says so rather than pretending otherwise.
Market value is roughly what a willing buyer would pay today. Assessed value is the figure your local assessor uses for tax purposes. In some places it equals market value. In others it is a set percentage of market value, called the assessment ratio. Mississippi, for example, states in its Department of Revenue FAQ that single-family, owner-occupied homes are assessed at 10% of true value, which is why Mississippi mill rates look very large compared with places that assess at 100%. If you only have an assessed value, type it into the first field and set the ratio to 100% so the ratio is not applied twice.
A mill is one-thousandth of a dollar, so a rate of 18.5 mills means $18.50 of tax for every $1,000 of taxable assessed value. Most bills are the sum of several rates: county, city or township, school district, and sometimes special districts such as fire, library, parks or water. Two houses with the same assessed value can have different bills if they sit in different school districts or cities. When you copy a rate from your bill, check whether it is the combined total or only one line of it.
Many areas offer an exemption that removes a set dollar amount from taxable value for an owner-occupied home. Others use a percentage, or give a credit against the final bill, and the rules differ by state. The Texas Comptroller, for instance, explains that its mandatory school-district homestead exemption is a fixed dollar amount, while an optional local exemption can be a percentage of appraised value, and that owners must generally apply. This calculator only models the fixed-dollar kind. If your benefit is a percentage or a credit, estimate its effect separately, or enter the dollar equivalent as an approximation.
A home valued at $285,000, a 100% assessment ratio, an 18.5 mill rate and no exemption. Assessed value is $285,000. Divide by 1,000 to get 285 units, then multiply by 18.5: 285 x 18.5 = $5,272.50 per year, or about $439 per month. As a share of the home's value that is about 1.85%.
Same home and mill rate, but the area assesses at 90% of market value. Assessed value becomes $256,500, so the tax is 256.5 x 18.5 = $4,745.25. The house did not change; only the local rule did. This is why comparing mill rates between places is meaningless unless you also know each place's assessment ratio.
Keep the 90% ratio and add a $50,000 fixed-dollar exemption. Taxable assessed value falls to $206,500, and the tax is 206.5 x 18.5 = $3,820.25. That is $1,452.25 less per year than Example 1 for the same $285,000 house, entirely because of one ratio and one exemption.
Two identical $285,000 homes, 100% ratio, no exemption. Town A has a combined rate of 15.2 mills and Town B has 24.6 mills. Town A: 285 x 15.2 = $4,332. Town B: 285 x 24.6 = $7,011. The difference is $2,679 a year for the same house, and it comes entirely from the local spending and tax base behind the rate. Compare the total annual cost, not just the listing price, when you choose where to buy.
Some bills and websites show a percentage instead of mills. To convert, multiply the percentage by 10: a 1.85% rate equals 18.5 mills, and a 0.5% rate equals 5 mills. You can then enter it in the mill-rate field with the assessment ratio at 100%.
Step 1. Find your latest assessment notice or tax bill. It usually lists the assessed value, the exemptions applied, and the rate or rates.
Step 2. Decide whether your number is a market value or an assessed value. If the bill shows an assessed value and no ratio, use it as the value and set the ratio to 100%.
Step 3. Add up the mill rates of every taxing body on the bill. Enter the total.
Step 4. Enter any fixed-dollar exemption that has actually been granted on your property, not one you only might qualify for.
Step 5. Press Calculate. Read the result as a base estimate, then compare it with last year's bill. A gap of more than a few percent usually means a fee, a credit, a cap or a rate change that this tool does not model.
Step 6. To test a "what if", change one input at a time. Raise the value by 10% to see what a reassessment might do, or raise the mill rate by one to see what a levy increase costs. One extra mill on a $285,000 assessed home is $285 per year.
An effective rate is the tax actually paid divided by the home's value, which lets you compare places that use different ratios and mill rates. The Tax Foundation calculates state effective rates for owner-occupied housing from U.S. Census Bureau American Community Survey data (tables B25082 and B25090). Its 2024 figures for a few states show how wide the spread is:
| State (2024, Tax Foundation / ACS) | Effective rate | On a $285,000 home |
|---|---|---|
| New Jersey | 1.88% | $5,358 |
| Illinois | 1.88% | $5,358 |
| Texas | 1.40% | $3,990 |
| California | 0.70% | $1,995 |
| Colorado | 0.50% | $1,425 |
| Alabama | 0.37% | $1,055 |
| Hawaii | 0.29% | $827 |
These are statewide averages from 2024 survey data. Effective rates vary by county and city, sometimes by more than the gap between states, and your own bill can differ because of your assessment, exemptions and local levies. Use the table to understand the range, and use your own bill to fill in the calculator. Source: Tax Foundation, "Property Taxes by State and County, 2024" (taxfoundation.org).
| Mill rate | Same as | Tax on $100,000 of taxable value | Tax on $285,000 |
|---|---|---|---|
| 5 mills | 0.5% | $500 | $1,425 |
| 10 mills | 1.0% | $1,000 | $2,850 |
| 15 mills | 1.5% | $1,500 | $4,275 |
| 18.5 mills | 1.85% | $1,850 | $5,272.50 |
| 25 mills | 2.5% | $2,500 | $7,125 |
The table assumes the rate applies to the whole amount shown, with a 100% assessment ratio and no exemption. Use it for a rough sense of scale, then enter your own figures above. Remember that the rate and the assessment ratio work together, so a higher mill rate does not always mean a higher bill.
It is built for first-time buyers who want to compare the annual cost of two listings, for owners who want to understand a reassessment notice, and for anyone setting a budget around an escrow payment. It is not a substitute for the figures your tax office publishes, and it does not know your local programs.
Mixing up market value and assessed value. Typing a sale price or an online home-value estimate into the field without applying your area's assessment ratio overstates the tax wherever the ratio is below 100%.
Using an old mill rate. Rates are normally set every year with local budgets. A rate from last year's listing or an old article may be out of date, so use the most recent bill.
Using only one component of the rate. Some public sources list just the county rate. Your bill is usually the sum of several rates.
Counting an exemption you do not have. Exemption rules vary, and in many places an owner must apply. A second home, a rental or an unfiled application may not qualify.
Forgetting reassessment. If your area reassesses every few years, the next notice can bring a large jump in assessed value even when the mill rate is flat.
Applying the ratio twice. This is the most common input error: entering an assessed value and also leaving a ratio below 100%.
Special assessments for sewers, sidewalks or neighborhood improvements are billed alongside property tax but are not calculated with the mill rate. Flat fees, such as a solid-waste or stormwater charge, may appear on the same bill. Some states cap yearly increases in taxable value or give credits to older or lower-income owners, and the rules differ widely, so ask your assessor which programs exist where you live.
If you pay through a mortgage escrow account, your lender usually collects about one-twelfth of the expected annual tax each month and pays the bill for you. Because the lender must review the account at least once a year, a change in your tax shows up in your mortgage payment with a delay. Our guide on escrow and reassessment walks through a numeric example, and the guide on reading your bill shows where each number lives.