Property taxes are calculated from the assessed value of your land and buildings, multiplied by your local tax rate
Your property tax bill comes from two numbers: what your local assessor says your property is worth, and the tax rate your county or municipality sets. The assessor estimates value based on recent sales of similar homes in your area, the condition of your building, the size of the lot, and what you could sell it for today. The tax rate is a percentage set by your local government — it varies widely by location and can change year to year based on local budget needs.
The formula is straightforward: assessed value × tax rate = annual property tax. A home assessed at $300,000 in a place with a 1.2% tax rate costs $3,600 per year. The same home in a place with a 0.8% rate costs $2,400. That difference matters, and it is why property taxes in one state or county can be half what they are in another.
Key Takeaways
- Assessed value is set by your local assessor and is based on what similar homes sold for recently, not what you paid for your home.
- Tax rates are set by your county or municipality and are expressed as a percentage of assessed value; they vary from under 0.5% to over 2% depending on location.
- Your assessed value can change every year or every few years depending on your state's reassessment schedule, even if you do nothing to your property.
- Some properties receive exemptions or reductions — homestead exemptions, agricultural exemptions, and senior or disability exemptions are common — which lower the assessed value or tax rate.
- You can challenge your assessed value through a formal appeal process if you believe the assessor overestimated what your property is worth.
How assessors determine property value
Your local assessor's office estimates the market value of your property by comparing it to homes that actually sold nearby within the past year or two. They look at sale price, square footage, lot size, age of the building, condition, number of bedrooms and bathrooms, and features like a garage or pool. If your neighborhood had five similar homes sell for $280,000 to $320,000 in the past 18 months, your home might be assessed somewhere in that range.
Assessors also use computer models that weight these factors — a newer roof or updated kitchen can raise the estimate, while deferred maintenance lowers it. They do not visit every property every year; many states reassess on a cycle of three to five years, or only when a property changes hands. Some assessors use mass appraisal software that processes thousands of properties at once, while others in smaller jurisdictions do more individual review.
The assessed value is usually lower than what you could actually sell your home for, because assessors are supposed to estimate fair market value, not the top price a motivated buyer might pay. However, in hot real estate markets, assessed values can lag behind actual prices, meaning you may pay less tax than you would if the assessment were current.
Tax rates and how they are set
Your local government — usually the county, but sometimes the city or a special district — sets the property tax rate each year based on its budget. If the county needs $50 million to run schools, roads, and services, and the total assessed value of all property in the county is $5 billion, the rate is 1%. If the budget grows to $60 million the next year, the rate might rise to 1.2%.
Tax rates are public information and are published by your county assessor or tax collector's office. They vary dramatically by location: New Jersey and Illinois have rates above 1.5%, while Hawaii and Alabama are below 0.5%. Within a state, rates can also differ between counties — a rural county might have a 0.9% rate while a wealthy suburb has 1.4% because the suburb funds more services or has lower total assessed value to spread costs across.
Some jurisdictions use a millage rate, which is the same thing expressed differently: a 1% tax rate is 10 mills, meaning $10 per $1,000 of assessed value. You may see your tax bill labeled in mills rather than a percentage, but the math is identical.
Reassessment cycles and when your value can change
Most states reassess property on a schedule — every year, every three years, or every five years — rather than only when you sell. During a reassessment year, the assessor updates your property's estimated value to reflect current market conditions. If your neighborhood appreciated 5% since the last assessment, your assessed value will likely rise 5% as well, even if you made no changes to your home.
Some states use assessment caps that limit how much your assessed value can increase in a single year, even if the market value jumped. California caps increases at 2% per year unless the property changes hands. Florida caps increases at 3% per year. These caps protect long-term homeowners from sudden tax spikes but can create situations where neighbors with identical homes pay different taxes because they bought at different times.
A few states reassess only when property is sold, which means your assessed value stays frozen until you transfer ownership. This protects you from rising taxes but can create unfairness when a neighbor buys an identical home for more and pays higher taxes on it when ready.
Exemptions and reductions that lower your tax bill
Most states and counties offer exemptions that reduce your assessed value or tax rate if you meet certain conditions. A homestead exemption is the most common — it lowers the assessed value of your primary residence by a fixed amount (often $25,000 to $50,000) or a percentage. You must own and live in the home to claim it, and you usually file once with your assessor's office.
Other exemptions target specific groups: seniors over a certain age, people with disabilities, veterans, farmers, and nonprofits. Some states offer a property tax freeze for seniors, which locks your tax bill at the level it was when you turned 65, even if your home's value rises. Agricultural exemptions allow farmland to be taxed based on its farm value rather than its development value, which can be dramatically lower.
To claim an exemption, you typically file a form with your assessor's office during a specific window — often in spring — and provide proof of your status (birth certificate for age, disability letter, military discharge papers). Missing the important date can cost you a year of savings, so check your local assessor's website for dates and requirements.
How to challenge your assessed value
If you believe your assessed value is too high, you can file a formal appeal with your assessor or a county board of appeals. The process varies by state, but most follow this path: you submit a written challenge (usually a straightforward form) within a important date window, often 30 days of receiving your assessment notice. You then present evidence that your home is worth less — recent appraisals, comparable sales of similar homes that sold for less, or documentation of major damage or needed repairs.
Many assessors will meet with you informally to review your evidence before a formal hearing. If you reach an agreement, your value is adjusted and your tax bill is recalculated. If you disagree, you can request a hearing before a board of appeals, where you present your case and the assessor presents theirs. The board decides whether to uphold, lower, or (rarely) raise your assessment.
Successful appeals usually rest on showing that comparable homes sold for significantly less than your assessed value, or that your home has a major defect the assessor did not account for. straightforward disagreeing with the value or saying you cannot afford the tax bill is not grounds for an appeal — the assessment is about market value, not your ability to pay.
Why property taxes vary so much between locations
A $400,000 home might cost $2,000 per year in property tax in one state and $8,000 in another, because both assessed values and tax rates differ dramatically. States with high income taxes and sales taxes often have lower property tax rates, while states with no income tax (like Texas and Florida) tend to have higher property tax rates to fund schools and services. Wealthy areas with high home values but lower tax rates can fund services with less tax burden per household, while rural areas with lower home values but higher rates struggle to raise enough revenue.
Local spending also matters: a county that funds its own schools, roads, and sheriff's office needs higher tax revenue than one where the state covers most costs. A county with an aging population and high service demands will have a higher rate than a growing county with younger residents and lower service costs per capita.
Frequently Asked Questions
Can my property tax go up if I do not sell my home?
Yes. Most states reassess property on a schedule, and your assessed value can rise if your neighborhood appreciates, even if you make no changes. Some states cap annual increases (California at 2%, Florida at 3%), while others have no cap. A few states only reassess when you sell, so your value stays frozen until then.
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 is often lower. In slow markets, assessed value may lag behind actual sales prices. In fast-moving markets, it may be lower than what you could sell for, but higher than what you paid years ago.
How do I find out what my home is assessed at?
Your assessed value appears on your property tax bill and on your county assessor's website, which is public record. Search your county name plus "assessor" to find the office, then look for an online property search tool where you can enter your address or parcel number.
If I improve my home, will my taxes go up?
Usually yes, but not when ready. Major improvements like a new roof, addition, or kitchen renovation are often added to your assessed value at the next reassessment cycle. Some assessors update values during the year if they learn of major work; others wait for the scheduled reassessment. Check with your local assessor about their timing.
What happens if I disagree with my assessed value?
File a formal appeal with your assessor or county board of appeals, usually within 30 days of receiving your assessment notice. Bring evidence that comparable homes sold for less or that your home has defects the assessor missed. If you and the assessor cannot agree, you can request a hearing before a board of appeals.