Property tax starts with your assessor's estimate of what your home is worth

Your property tax bill is not based on what you paid for your house or what you could sell it for today. It is based on an assessed value — a number your county or municipal assessor assigns to your property. The assessor looks at your home's characteristics (size, age, condition, location) and compares it to similar homes that sold recently in your area. That assessed value is then multiplied by your local tax rate to produce your bill.

The assessed value is usually lower than market value. If your home is worth $400,000 on the open market, the assessor might assign it an assessed value of $300,000 or $350,000, depending on your state's assessment practices. The tax rate — expressed as a percentage or as dollars per $1,000 of assessed value — is set by your city, county, or school district and changes year to year based on their budget needs.

Key Takeaways

  • Your property tax bill equals your home's assessed value multiplied by your local tax rate, and both numbers change annually.
  • The assessor determines assessed value by comparing your home to recent sales of similar properties in your area, not by what you paid or what it could sell for.
  • Tax rates are set by local government bodies (city, county, school district) and vary widely by location — the same house can have very different tax bills in different towns.
  • You can usually find your assessed value and tax rate on your county assessor's website or your property tax bill itself.
  • If you believe the assessed value is wrong, most counties allow you to file a formal challenge called an assessment appeal or grievance.

Where the assessed value comes from

The assessor's office maintains records on every property in the county. When you buy a home, the sale price is recorded, but that does not automatically become your assessed value. Instead, the assessor uses a mass appraisal process: they gather data on hundreds or thousands of recent sales, note the features of each property (square footage, lot size, age, condition, number of bedrooms), and build a model to estimate value.

Your home is then placed into a category with similar homes, and the model produces an estimated value. Some assessors use computer-assisted mass appraisal (CAMA) software; others still rely on manual inspection and comparison. The frequency of reassessment varies by state. Some counties reassess every year; others do it every three to five years. A few states (like California) reassess only when the property changes hands.

The assessor may also conduct a physical inspection of your home, either every few years or only if you request one or if major changes are visible from the street. If you have added a deck, finished a basement, or made other improvements, the assessor may increase the assessed value to reflect that work.

How the tax rate is applied

Once the assessed value is set, your local government applies a tax rate. This rate is usually expressed in one of two ways: as a percentage (for example, 1.2% of assessed value) or as a dollar amount per $1,000 of assessed value (for example, $12 per $1,000). Both mean the same thing.

If your home has an assessed value of $300,000 and the tax rate is 1.2%, your annual tax bill would be $3,600. If the rate is expressed as $12 per $1,000, you divide $300,000 by $1,000 (= 300) and multiply by $12 (= $3,600). The tax rate is set by your city, county, school district, or a combination of these, and it changes each year as their budgets change. A town that needs more revenue for schools or infrastructure may raise the rate; one with a surplus may lower it.

The tax rate is public information and is usually published by the assessor's office or the county treasurer's office. You can find it on your property tax bill or by calling your local assessor.

Why the same house costs different amounts to own in different places

A $400,000 home in one county might have a tax bill of $4,000 per year, while an identical home in a neighboring county might cost $6,000 or $2,500. The difference comes down to local tax rates, which reflect local spending priorities and revenue needs. A county with high school funding, extensive services, or recent infrastructure projects will have a higher rate than one with lower spending.

Assessed values can also differ. Some counties assess homes at 100% of market value; others assess at 50%, 60%, or another percentage. This is called the assessment ratio. If two counties have the same tax rate but different assessment ratios, the bills will differ. Additionally, some states offer homestead exemptions or other reductions that lower the assessed value for owner-occupied homes, which also affects the bill.

Finding your assessed value and tax rate

Your property tax bill shows both numbers, usually near the top. The bill will list the assessed value, the tax rate (or the total tax owed), and the due date. If you do not have a recent bill, you can find this information on your county assessor's website. Most assessor offices maintain searchable databases where you can enter your address and see the assessed value, property description, and recent assessment history.

If the website does not have a search tool, call the assessor's office directly. They can tell you the current assessed value, when it was last updated, and what the local tax rate is. Some assessor offices also send out assessment notices in the mail each year, which include the assessed value and explain any changes from the previous year.

What to do if you think the assessed value is wrong

If you believe your home has been assessed too high, you can file a formal challenge. The process is called an assessment appeal, grievance, or review, depending on your state. Most counties have a deadline — often 30 to 45 days after the assessment notice is mailed — so act quickly if you want to challenge it.

To file an appeal, you typically submit a written request to your county assessor or a board of assessment appeals. You will need to explain why you think the value is wrong and provide evidence: recent appraisals, comparable sales in your area, photographs of damage or poor condition, or documentation of major repairs needed. Some counties allow you to present your case in person at a hearing; others review appeals on paper only.

If the assessor agrees that the value should be lower, they will issue a revised assessment. If you disagree with their decision, you can usually appeal to a county board or, in some states, to tax court. This process is free or low-cost, but it does require time and documentation on your part.

Frequently Asked Questions

Is my property tax bill the same every year?

No. The assessed value and tax rate both change annually. The assessed value may increase if your home appreciates or if you make improvements, and it may decrease if the market declines or if you successfully appeal. The tax rate changes based on local government budgets. Some states cap how much the assessed value can increase in a single year, which limits how much your bill can rise.

What is the difference between assessed value and market value?

Market value is what your home would sell for today. Assessed value is what the assessor estimates it is worth for tax purposes, and it is usually lower. The assessor uses recent sales of similar homes to estimate assessed value, not an actual appraisal of your specific property. Market value is determined by what buyers are willing to pay; assessed value is determined by a formula applied to many homes at once.

Can I lower my property tax bill without appealing the assessment?

Yes, in some cases. Many states offer homestead exemptions that reduce the assessed value for owner-occupied homes. Some offer exemptions for seniors, veterans, or people with disabilities. You may also be able to deduct the cost of major repairs or damage from the assessed value. Check your county assessor's website or call to learn what exemptions you may be may have access to to.

How often is my home reassessed?

This varies by state and county. Some reassess every year; others do it every three to five years. A few states reassess only when the property is sold. You can find out your county's reassessment schedule by calling the assessor's office or checking their website. Even if a full reassessment is not done, the assessor may update the value based on building permits, sales data, or physical inspections.

What happens if I disagree with the assessor's decision on my appeal?

Most counties allow you to appeal to a board of assessment appeals or a county board of supervisors. If you still disagree, you may be able to take the case to tax court or state court, depending on your state's laws. This step usually requires hiring a tax attorney or appraiser, so weigh the cost against the potential savings on your tax bill.