Property tax is calculated by multiplying your home's assessed value by the millage rate set by your local government, then dividing by 1,000

The formula is straightforward: Assessed Value × Millage Rate ÷ 1,000 = Annual Property Tax. A millage rate is expressed in mills, where one mill equals $1 of tax per $1,000 of assessed property value. If your home is assessed at $300,000 and your millage rate is 15 mills, you would owe $4,500 per year in property tax. The millage rate itself varies by location — it depends on what your county, school district, and municipality need to fund that year.

The reason property tax works this way is that it funds local services: schools, roads, fire departments, libraries, and county administration. Unlike income tax, which is collected by the federal government and redistributed, property tax stays in your community. The millage rate changes annually because local budgets change. If your school district needs more money for new buildings or your county faces higher costs, the millage rate rises. If revenues from other sources increase, it may fall.

Key Takeaways

  • Multiply your home's assessed value by the millage rate, then divide by 1,000 to find your annual property tax bill.
  • The assessed value is not the market price of your home — it is determined by your county assessor and is usually lower.
  • Millage rates are set by your county, school district, and municipality separately, and each adds to your total tax bill.
  • You can find your assessed value on your property tax bill or your county assessor's website, and your millage rate on your county tax collector's website.
  • Property tax bills are usually due once or twice per year, depending on your state and county.

Where to find your assessed value and millage rate

Your assessed value appears on your property tax bill, which you receive from your county tax collector or assessor's office. You can also look it up on your county assessor's website — most counties now post property records online and searchable by address or parcel number. The assessed value is not what you paid for your home or what it would sell for today. It is an estimate made by the county assessor, usually lower than market value, and it is recalculated periodically (every three to five years in most states, though some reassess annually).

Your millage rate is published by your county tax collector, usually on their website or in a public notice in the local newspaper. Because multiple taxing bodies contribute to your bill — the county, the school district, the city or township, and sometimes special districts like fire or water — you will see separate millage rates for each. Add them together to get your total millage rate. For example, if the county rate is 5 mills, the school rate is 8 mills, and the city rate is 2 mills, your total is 15 mills.

Understanding assessed value versus market value

The assessed value is the number that matters for your tax calculation, and it is almost always lower than what your home would sell for. A county assessor estimates assessed value by looking at recent sales of similar homes in your area, the condition of your property, and any improvements you have made. The goal is to create a fair system where homes of similar value pay similar taxes, but assessors work with incomplete information and cannot inspect every home every year.

In some states, assessed value is capped or grows slowly even if your home's market value rises sharply. California's Proposition 13, for example, limits assessed value growth to 2 percent per year unless the property is sold. In other states, assessed value tracks market value more closely. This matters because two identical homes in the same county can have very different tax bills if one was recently sold and reassessed while the other was not. You can challenge your assessed value if you believe it is too high — most counties have a formal appeal process, usually called a property tax appeal or assessment challenge, with a important date that falls in spring or early summer.

How millage rates are set and why they change year to year

Each taxing body — county, school district, city — calculates how much money it needs to operate and divides that by the total assessed value of all property in its jurisdiction to arrive at a millage rate. If your school district needs $50 million to run schools and the total assessed value of all property in the district is $5 billion, the millage rate is 10 mills ($50 million ÷ $5 billion × 1,000). The next year, if the district needs $52 million and assessed values have risen to $5.2 billion, the rate might stay at 10 mills or drop slightly.

Millage rates rise when a jurisdiction's costs increase faster than assessed values, or when voters approve a new tax to fund a specific project. Rates fall when assessed values grow faster than costs, or when a temporary tax expires. Some states require voter approval before a millage rate can rise above a certain level, while others allow the rate to rise without a vote. Your county tax collector's office can explain which rates in your bill are fixed and which can change, and whether any are temporary.

Step-by-step calculation example

Suppose your home has an assessed value of $250,000. Your property tax bill shows the following millage rates: county 4 mills, school district 9 mills, city 3 mills, and fire district 1 mill. Your total millage rate is 17 mills.

The calculation is: $250,000 × 17 ÷ 1,000 = $4,250. Your annual property tax bill is $4,250. If your county collects taxes twice per year, you would pay $2,125 in spring and $2,125 in fall. If it collects once per year, you would pay $4,250 in a single bill, usually in late fall or winter.

If your assessed value were $300,000 instead, the bill would be: $300,000 × 17 ÷ 1,000 = $5,100. A $50,000 difference in assessed value creates a $850 difference in annual tax. Over a decade, that is $8,500 — a meaningful amount that makes it worth checking whether your assessed value is accurate.

What happens if your assessed value or millage rate changes

When your county reassesses property, your assessed value may rise or fall. A rise triggers a higher tax bill; a fall lowers it. You will receive a notice of the new assessed value, usually in the mail, with instructions on how to appeal if you disagree. The appeal important date is typically 30 to 60 days from the notice date, and the process usually involves submitting comparable sales data or a professional appraisal to show that the assessed value is too high.

When a millage rate changes, the effect is when ready. If your county raises the school millage rate from 8 mills to 9 mills, your tax bill rises by $250 per $1 million of assessed value (1 mill × $1,000,000 ÷ 1,000 = $1,000, so 0.1 mills = $100 per $1 million). You do not appeal a millage rate change the way you appeal an assessed value — instead, you can attend public hearings where the rate is set and voice your opinion, or contact your county commissioners or school board members.

How property tax bills are structured and paid

Your property tax bill itemizes each millage rate and shows what portion of your bill goes to each service. This transparency helps you see where your money goes: typically 40 to 50 percent to schools, 20 to 30 percent to county services, 10 to 20 percent to your city or township, and smaller amounts to special districts. The bill also shows whether you have any exemptions (such as a homestead exemption, which lowers assessed value for your primary residence) and whether you owe any penalties for late payment.

Payment methods vary by county. Most allow you to pay online through the tax collector's website, by mail, or in person. Some accept automatic bank transfers. If you have a mortgage, your lender may require you to pay property tax through an escrow account, where the lender collects a portion of your monthly mortgage payment and pays the tax bill on your behalf. This protects the lender's interest in the property but means you do not receive a separate bill — the amount is straightforward deducted from your mortgage payment.

Frequently Asked Questions

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

You cannot lower it yourself, but you can challenge it if you believe it is too high. File a property tax appeal with your county assessor during the appeal window (usually spring). You will need to show comparable sales of similar homes or hire an appraiser. Success is not may provide — assessors reject many appeals — but if you win, your assessed value drops and so does your bill.

Why is my property tax bill different from my neighbor's if we live on the same street?

Your assessed values are likely different. Homes are assessed individually based on size, condition, improvements, and recent sales data. Even identical homes can have different assessed values if one was recently renovated, if one is on a larger lot, or if one was recently sold and reassessed while the other was not. You can compare assessed values on your county assessor's website.

What is a homestead exemption and does it affect my millage rate calculation?

A homestead exemption lowers your assessed value if your home is your primary residence. For example, it might reduce your assessed value by $50,000. This lowers your tax bill but does not change the millage rate itself — the rate is still applied to your reduced assessed value. You must file for the exemption with your county assessor; it does not happen automatically.

If I pay property tax through my mortgage escrow account, do I still need to understand the millage rate?

Yes. Your lender estimates your annual tax bill and divides it into monthly payments added to your mortgage. If your assessed value or millage rate changes, your escrow payment will adjust at the next annual review. Understanding the calculation helps you spot errors and know whether an escrow increase is justified.

Do I owe property tax if I own land but have not built on it?

Yes. Vacant land is assessed and taxed the same way as improved property. The assessed value is usually lower than for a home, but the millage rate applies to it. If you own raw land, you will receive a property tax bill annually unless the land is exempt (for example, if it is used for agriculture or conservation).