The Basic Formula: Assessed Value Times Tax Rate

Property tax is calculated by multiplying your property's assessed value by the tax rate set by your local government. That's the entire formula. The assessed value is what your county assessor decides your property is worth for tax purposes — not the price you paid for it or what it would sell for today. The tax rate is a percentage or dollar amount per $1,000 of assessed value, and it varies by county, city, and school district.

Here's a concrete example: if your home is assessed at $300,000 and your local tax rate is 1.2% (which means $12 per $1,000 of value), your annual property tax bill would be $3,600. That $300,000 figure is what matters, not your purchase price or current market value.

The tax rate itself is built from multiple layers. Your county sets a base rate, your city or township adds its own rate, and your school district adds another. When you see your bill, it usually shows the combined rate as a single number, but behind it are three or more separate government bodies taking a cut.

Key Takeaways

  • Property tax equals assessed value multiplied by the tax rate, and the assessed value is determined by your county assessor, not by what you paid or what your home is worth on the market.
  • Tax rates vary significantly by location and are set by your county, city, and school district separately, so two identical homes in different counties can have very different bills.
  • Your assessed value is usually updated every one to four years depending on your state, and you can request a reassessment or file an appeal if you believe it is wrong.
  • The bill you receive shows the total tax owed, but breaking it down by jurisdiction (county, city, school) helps you understand which government body is taking the largest share.

How Assessed Value Is Determined

The assessed value starts with your county assessor's office. Assessors use several methods to arrive at a number. The most common is the sales comparison approach: they look at what similar homes in your area sold for recently and adjust for differences in size, condition, and features. If your neighborhood has few recent sales, they may use the cost approach instead, which estimates what it would cost to rebuild your home from scratch, then subtracts depreciation. Commercial and rental properties often use the income approach, which bases value on how much rent or income the property generates.

Assessors do not visit every property every year in most states. Instead, they reassess on a cycle — every year in some places, every three years in others, every four years in others. During the years between reassessments, your assessed value may stay flat or increase by a small percentage set by state law. When a reassessment year arrives, the assessor may send someone to inspect your property, or they may update the value based on public records, recent sales data, and photographs.

You can challenge an assessed value if you believe it is wrong. The process varies by state, but typically involves filing a formal appeal with your county assessor or a local board of review, usually within 30 to 45 days of receiving your assessment notice. You will need evidence: recent appraisals, comparable sales in your area, photographs of damage or needed repairs, or documentation of code violations that reduce value.

Understanding Tax Rates and How They Change

Tax rates are set by elected officials in your county, city, and school district, and they change based on budget needs. If your school district needs more money for operations, the school board may vote to raise the school tax rate. If your county has a budget shortfall, the county commissioners may raise the county rate. These decisions happen independently, so your total tax bill can jump even if your home's assessed value stays the same.

Rates are usually expressed as a percentage of assessed value (like 1.2%) or as a dollar amount per $1,000 of assessed value (like $12 per $1,000). Both mean the same thing. Some states cap how much a tax rate can increase in a single year, while others allow unlimited increases. A few states have homestead exemptions that reduce the assessed value for owner-occupied homes, which lowers the tax bill automatically.

You can find your tax rate on your property tax bill or by contacting your county assessor's office. The bill usually breaks down the rate by jurisdiction — showing how much goes to the county, how much to the city, and how much to schools. This breakdown helps you see which government body is responsible for the largest portion of your bill.

What Happens Between Assessment and Your Bill

Once the assessor sets a value and the tax rates are set, the calculation is straightforward, but the timeline can be confusing. Your assessed value may be based on sales data from 18 months ago. The tax rates may have been set months before you receive your bill. By the time you get the bill in your mailbox, the numbers reflect decisions made at different times in the past year.

Some jurisdictions allow tax abatements or exemptions that reduce your bill after the calculation is complete. These might apply if you are over 65, disabled, a veteran, or a farmer. You usually have to request these separately — they do not happen automatically. If you may have access to, you file paperwork with your assessor or a local office, and if approved, your bill is reduced or eliminated for that year.

Your bill also includes any special assessments or fees your local government has added. These might be for water, sewer, trash collection, or a local improvement district (like a new road or drainage project). These are separate line items on your bill, calculated differently from property tax, but they arrive on the same invoice.

Comparing Tax Burdens Across Locations

Because tax rates and assessment methods vary so widely, two homes worth the same amount can have very different tax bills depending on where they are located. A $400,000 home in one county might owe $4,000 per year in property tax, while an identical home in another county owes $8,000. This difference comes from the tax rates set by local governments, not from anything about the homes themselves.

If you are considering moving or comparing neighborhoods, ask for the property tax bill for a specific address. Do not rely on a general "tax rate" — ask for the actual bill or the combined rate for that exact location. County assessor websites often have search tools where you can look up a specific address and see its assessed value and tax rate. Some sites even show recent sales prices, which lets you compare the assessed value to what homes actually sold for.

State law also affects how much tax you pay. Some states have assessment caps that limit how much an assessed value can increase each year, even if the market value rises sharply. California's Proposition 13, for example, caps increases at 2% per year. Other states reassess at market value every year with no cap. These rules can make a huge difference in your long-term tax burden.

Reading Your Property Tax Bill

Your bill shows the assessed value, the tax rate (or rates), and the amount owed. It may also show the previous year's bill for comparison, any exemptions or abatements applied, and a breakdown by jurisdiction. Some bills are one page; others are several pages with detailed explanations.

The key numbers to understand are: the assessed value (the number being taxed), the tax rate or rates (the percentage or per-$1,000 amount), and the total tax owed (the result of multiplying the two). If you see a line item for "school tax," "county tax," and "city tax," those are the results of applying each jurisdiction's rate to your assessed value. Add them together and you get your total bill.

If your bill looks wrong, start by checking whether your assessed value matches what you expect. If it is much higher than similar homes in your area, or much higher than what you paid for the home, that is worth investigating. If the assessed value looks reasonable but the bill is higher than last year, check whether the tax rates changed or whether your assessed value increased. Your assessor's office can explain the numbers on your bill and tell you how to appeal if you disagree.

Frequently Asked Questions

Why is my assessed value different from what I paid for my home?

Assessed value and purchase price are two different things. Your assessed value is what the county assessor estimates your home is worth for tax purposes, based on comparable sales and other factors. If you bought your home years ago, the assessed value has likely increased even if you paid less. If you bought recently, the assessed value might be lower than your purchase price if the market has cooled or if the assessor uses a different method than the sale price.

Can I lower my property tax by lowering my assessed value?

You cannot lower your assessed value directly, but you can challenge it if you believe it is wrong. File an appeal with your county assessor or board of review, usually within 30 to 45 days of receiving your assessment notice. You will need evidence like a recent appraisal, comparable sales data, or documentation of damage or needed repairs. If your appeal is successful, your assessed value is reduced, which lowers your tax bill going forward.

What if my tax bill went up but my assessed value stayed the same?

Your tax rate changed. This happens when your county, city, or school district votes to raise its tax rate to cover budget needs. Even if your home's assessed value does not change, a higher tax rate means a higher bill. Check your bill to see which jurisdiction raised its rate — it is usually the school district or county.

How often is my assessed value updated?

This depends on your state and county. Some places reassess every year, others every two to four years. During years when no reassessment happens, your assessed value may stay flat or increase by a small percentage set by state law. You can contact your county assessor to find out the reassessment schedule for your property.

Do I have to pay property tax if I own my home outright?

Yes. Property tax is owed by the owner of the property, whether you have a mortgage or not. If you have a mortgage, your lender may collect property tax as part of your monthly payment and pay it on your behalf, but you are still legally responsible for it. If you own the home outright, you receive the bill directly and must pay it yourself.