Property tax starts with your home's assessed value, not what you paid for it
Your property tax bill comes from multiplying your home's assessed value by your local tax rate. The assessed value is an estimate of what your home is worth, set by your county or municipal assessor's office. It is almost never the same as the price you paid or what a real estate agent says it is worth today. The tax rate is a percentage set by your local government — it varies by county, city, and school district.
The assessor does not call you to ask what your home is worth. Instead, they use public records: what similar homes sold for recently, the size and age of your building, the lot size, and any improvements you have made. Some assessors physically inspect homes every few years; others work from records and sales data alone. The frequency and method vary by state and county.
Once you know the assessed value and the tax rate, the math is straightforward. If your home is assessed at $300,000 and your tax rate is 1.2 percent, you owe $3,600 per year. Most homeowners pay this in two or four installments, usually through an escrow account managed by their mortgage lender.
Key Takeaways
- Your property tax bill is calculated by multiplying your home's assessed value (set by the county assessor) by your local tax rate (set by your city, county, and school district).
- The assessed value is based on public sales records, home characteristics, and sometimes a physical inspection — not on what you paid for the house.
- Tax rates vary widely by location; a home worth the same amount can have a bill that differs by thousands of dollars depending on where it sits.
- 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 your assessed value is wrong, most counties allow you to file a formal challenge called an appeal or grievance within a set window each year.
Where to find your assessed value and tax rate
Your property tax bill shows both numbers, though they may be labeled differently depending on your county. Look for "assessed value," "taxable value," or "appraised value" — these mean roughly the same thing. The tax rate may appear as a percentage, a decimal, or as "mills per dollar" (which is the rate per $1,000 of assessed value).
If you do not have a recent bill, visit your county assessor's website. Most counties now have online portals where you can search by address or parcel number and see the assessed value, recent sales history of your home, and sometimes the tax rate breakdown by district. The assessor's office is a county function, not a state one, so you need the right county — not just the state.
Your county tax collector or treasurer's office also publishes tax rate information, usually broken down by school district, city, and county portions. These rates change annually and are set by elected officials in each jurisdiction, so the total rate you pay reflects decisions made by multiple bodies.
How assessed value is determined
Assessors use one or more of three main methods. The sales comparison approach looks at what similar homes in your area sold for recently and adjusts for differences in size, condition, and features. The cost approach estimates what it would cost to rebuild your home from scratch, then subtracts depreciation. The income approach is used mainly for rental properties and is based on the income the property generates.
Most residential homes are assessed using sales comparison, because it reflects what buyers actually pay. An assessor might look at five recent sales of similar homes within a mile of yours, adjust each sale price up or down based on square footage and condition, and average the results. If your home has unusual features — a pool, a recent major renovation, or significant damage — the assessor may adjust the comparison value accordingly.
The frequency of reassessment varies by state. Some states reassess every year; others do it every three to five years or only when a property changes hands. A few states use a hybrid system where the assessed value is adjusted annually by a set percentage, even if no formal reassessment happens. Check your state's rules on your assessor's website.
Tax rate variations by location
Two identical homes in different counties can have vastly different tax bills because tax rates are set locally. A home worth $400,000 might owe $4,000 per year in one county and $8,000 in another, depending on how much revenue the local schools, city, and county need to raise through property tax.
Your total tax rate is the sum of rates from multiple jurisdictions: your county, your city or township, your school district, and sometimes special districts for fire, water, or other services. Each sets its own rate based on its budget. When you see your bill broken down, you can see how much of your payment goes to each entity.
States also differ in how much they cap or limit tax rate increases. Some states allow assessors to raise assessed values freely; others cap annual increases at a percentage like 2 percent per year, regardless of market changes. These caps protect homeowners from sudden spikes but can mean assessed values lag behind actual market values over time.
What happens if you think your assessed value is wrong
If you believe your home is assessed too high, you can file a formal challenge. The process and timeline vary by state and county, but the general steps are the same: gather evidence, file a written appeal or grievance within the allowed window (usually 30 to 60 days after you receive your bill), and present your case to a review board or assessor's office.
Strong evidence includes a recent professional appraisal showing a lower value, recent sales of comparable homes that sold for less, photos of damage or needed repairs, or documentation that the assessor made a factual error (wrong square footage, wrong number of bedrooms, or a home listed as two-story when it is one-story). Do not rely on what you think the home is worth or what you paid for it; use market data instead.
The review process is usually free and does not require a lawyer, though some people hire a property tax consultant or attorney if the stakes are high. If you lose the appeal, you can often file again the next year if circumstances change — for example, if your home needs major repairs or if comparable sales drop significantly.
How improvements and changes affect your assessed value
When you add a room, finish a basement, or install a new roof, the assessor may increase your assessed value because the home is now worth more. Some counties discover improvements through building permits; others find them during routine reassessment or when you sell. A few states allow homeowners to report improvements themselves.
The increase in assessed value is usually proportional to the cost of the improvement, but not always equal to it. A $50,000 kitchen renovation might raise your assessed value by $40,000 to $50,000, depending on how much that improvement adds to the home's market value. A $20,000 repair to fix damage does not typically raise the value — it just brings the home back to its previous condition.
Damage or deterioration can lower your assessed value if you report it and provide evidence. If a fire, flood, or major structural problem reduces your home's worth, you can request a reassessment. Some counties do this automatically after a disaster; others require you to file a claim.
Understanding exemptions and special assessments
Many homeowners may have access to for exemptions that reduce their assessed value or tax bill. Common ones include homestead exemptions (available to primary residents in many states), exemptions for seniors or disabled homeowners, and exemptions for veterans. Each state and county sets its own exemptions, so what is available depends on where you live.
A homestead exemption might reduce your assessed value by a fixed amount — say, $50,000 — or by a percentage. If you may have access to, you usually file a form with the assessor's office once, and the exemption applies to future bills automatically. You may need to reapply if you move or if your status changes.
Some properties also face special assessments — additional charges for local improvements like new sidewalks, street lights, or sewer upgrades. These are separate from regular property tax and are usually spread over several years. They appear as a line item on your bill and apply only to properties that benefit from the improvement.
Frequently Asked Questions
Can my property tax bill go down if my home loses value?
Yes, but only if you file an appeal and prove the lower value with evidence like a recent appraisal or comparable sales. Assessors do not automatically lower values when the market drops; you have to request it. Some states with assessment caps do lower values automatically if the market falls sharply, but this is not common.
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 for tax purposes, and it often lags behind market value — sometimes by years. In a rising market, assessed value is usually lower than market value. In a falling market, it may be higher.
Do I have to pay property tax if I own my home outright?
Yes. Property tax is owed by the owner, whether or not there is a mortgage. If you have a mortgage, your lender usually collects the tax through escrow and pays it on your behalf, but you are still legally responsible. If you own the home free and clear, you pay the tax directly to your county.
How often does the assessor reassess my home?
This depends on your state and county. Some reassess annually; others do it every three to five years or only when the property sells. Check your county assessor's website or call their office to find out the schedule for your area.
What if I disagree with the assessor's decision on my appeal?
Most counties allow a second level of appeal to a county board or court, though the process and deadlines vary. You typically have 30 to 90 days to file. Some people hire a property tax attorney for this stage, especially if the assessed value is high enough to make legal fees worthwhile.