Property tax starts with your home's assessed value, not its sale price
Your property tax bill is based on what your local assessor says your home is worth, multiplied by your local tax rate. That assessed value is usually lower than what you could sell the house for — assessors use formulas based on recent sales of similar homes in your area, not market appraisals. The tax rate itself is set by your county or municipality and varies widely depending on what services that area funds through property tax: schools, roads, fire departments, libraries.
The math is straightforward once you know the two numbers. If your home is assessed at $300,000 and your tax rate is 1.2%, you owe $3,600 per year. But the hard part is understanding where that assessed value comes from and whether it's correct, because mistakes happen and they cost you money.
Key Takeaways
- Your property tax bill equals your home's assessed value times your local tax rate, and both numbers are public record you can look up.
- Assessed value is not the same as market value — assessors use sales data from comparable homes, not appraisals, and they update assessments on different schedules depending on your state.
- You can challenge your assessment if you believe it's too high, and the process usually involves filing a formal appeal with your county assessor's office by a specific deadline.
- Tax rates are set by local governments and include money for schools, infrastructure, and services; they change year to year and vary dramatically between neighborhoods and counties.
- Your actual bill may be lower than the calculation if your state or county offers exemptions for homeowners, seniors, veterans, or people with disabilities.
How assessors determine your home's value
Most assessors use a method called mass appraisal, which means they value thousands of homes using the same formula rather than inspecting each one individually. The formula typically looks at recent sales of homes similar to yours — same size, age, condition, location — and adjusts up or down based on differences. If three comparable homes sold for $295,000, $305,000, and $310,000, your home might be assessed at $305,000 even if you never listed it.
Some assessors also use income approach (for rental properties) or cost approach (what it would cost to rebuild), but the sales comparison method is most common for residential homes. The assessor's office has records of every sale in the county, so they can pull actual transaction data rather than guessing.
Assessment schedules vary by state. Some states reassess every year; others do it every three, four, or five years. A few states reassess only when a property changes hands. Check your state assessor's website or call your county assessor's office to find out when your home was last assessed and when the next assessment is scheduled.
Finding your assessed value and tax rate
Both numbers are public record. Start by visiting your county assessor's website — search "[your county] assessor" plus your state. Most assessor offices have an online database where you can search by address or parcel number and see the assessed value, the land value, the building value, and sometimes photos of your home from the assessor's records.
Your tax rate is usually listed on your property tax bill itself, often as a millage rate (the amount per $1,000 of assessed value). You can also find it on your county's tax collector website or by calling the assessor's office. The rate is public information and does not change based on individual properties — everyone in your tax district pays the same rate.
Once you have both numbers, the calculation is: (Assessed Value ÷ 1,000) × Millage Rate = Annual Tax. If your assessed value is $250,000 and the millage rate is 15 mills (1.5%), the math is (250,000 ÷ 1,000) × 15 = $3,750.
Challenging an assessment you think is wrong
If you believe your assessed value is too high, you can file a formal challenge called an assessment appeal or property tax appeal. The process and deadlines vary by state, but most require you to file within 30 to 45 days of receiving your assessment notice. Missing the deadline usually closes the door for that year.
To build your case, gather evidence that your home is worth less than the assessed value. This means recent sales of truly comparable homes — same neighborhood, similar size and condition, sold within the last six months if possible. You can find this data through real estate websites like Zillow or Redfin, or by asking a local real estate agent for a market analysis. You can also get a professional appraisal, though this costs $300 to $500 and is not required.
File your appeal with your county assessor's office or the board of appeals (the name varies by state). Include your evidence, a cover letter explaining why you think the value is wrong, and a copy of your assessment notice. Some counties allow you to submit everything by mail; others require an in-person hearing. Call your assessor's office to ask what they need and what the deadline is for your specific county.
Tax exemptions that lower your bill
Many states and counties reduce or eliminate property tax for certain homeowners. Common exemptions include homestead exemptions (for primary residences), senior exemptions (usually age 65 or older), veteran exemptions, and disability exemptions. Some states also offer exemptions for agricultural land or historic properties.
An exemption does not mean you pay nothing — it usually means a portion of your home's value is not taxed. A homestead exemption might exempt the first $50,000 of value, so if your home is assessed at $300,000, you only pay tax on $250,000. The exact amount varies by state and sometimes by county within a state.
You have to claim an exemption; it is not automatic. Contact your county assessor's office or tax collector to ask what exemptions you might be may have access to to and what documents you need to submit. Common requirements include proof of residency, proof of age (for senior exemptions), a discharge paper (for veteran exemptions), or a disability information letter. Deadlines for claiming exemptions vary, so ask when you call.
Why your tax bill changes year to year
Your property tax can increase for three reasons: your assessed value went up, your tax rate went up, or both. If your home was reassessed and the new value is higher, your tax goes up. If your county or school district raised the millage rate to fund new services or cover budget shortfalls, your tax goes up even if your assessed value stayed the same.
Some states cap how much your assessed value can increase in a single year — for example, Florida caps increases at 3% per year even if the market value jumped higher. Other states have no cap. Check your state's rules to understand whether your assessment can jump significantly or whether it's limited.
Your bill may also include special assessments for local improvements like new roads, water lines, or sewer upgrades. These are separate from the regular property tax and appear as a line item on your bill. They are usually temporary and end once the project is paid for.
Understanding the difference between assessed value and market value
Your home's assessed value and its market value are often different, and that's normal. Market value is what someone would actually pay for your home today. Assessed value is what the assessor calculated using their formula, and it lags behind the market. If your neighborhood is hot and homes are selling fast, your assessed value might be lower than market value. If the market is slow, assessed value might be higher.
This matters because it means your property tax bill does not automatically track with what your home is worth. You could sell your house for $400,000 but still owe tax based on a $350,000 assessment until the next reassessment cycle. Conversely, if your home drops in value but the assessment has not been updated, you might be overpaying.
Some states try to keep assessed values close to market value by reassessing frequently. Others allow assessed values to drift, which is why a challenge makes sense if you have evidence that the gap is large.
Frequently Asked Questions
Can I look up what my neighbors' homes are assessed at?
Yes. Assessment records are public, and most county assessor websites let you search by address. You can see your neighbor's assessed value, land value, building value, and sometimes the sale price when they bought. This is useful for comparing your assessment to similar homes in your area.
What happens if I don't pay my property tax bill?
Your county can place a lien on your home, meaning they have a legal claim against it. If you continue not to pay, the county can eventually foreclose and sell your home to recover the unpaid taxes and penalties. If you're struggling to pay, contact your county tax collector about payment plans or hardship programs before you fall behind.
Does my property tax bill include homeowners insurance?
Not usually. Property tax and homeowners insurance are separate bills. However, if you have a mortgage, your lender may require you to pay both into an escrow account, and the lender pays them from that account. Ask your mortgage servicer if your insurance is bundled into your monthly payment.
How do I know if my county is reassessing homes this year?
Call your county assessor's office or check their website. They publish a reassessment schedule, and you can find out whether your home is due for a new assessment. Some counties reassess in phases, so your neighborhood might be reassessed in year two while another area is reassessed in year three.
Can I deduct property tax from my federal income tax?
Yes, but with limits. You can deduct state and local property taxes (SALT) on your federal return, but the total deduction for all state and local taxes combined is capped at $10,000 per year. This applies only if you itemize deductions rather than taking the standard deduction. Talk to a tax professional about whether itemizing makes sense for your situation.