A tax assessment is the value a local government assigns to your property for tax purposes
A tax assessment is an official estimate of what your home or land is worth, used to calculate how much property tax you owe each year. The assessment is not the same as the market value — it is a number set by your county or municipality that determines your tax bill. Most assessments are lower than what your home would sell for, because they are based on formulas rather than actual sales prices.
Your local assessor's office conducts these assessments, usually every one to five years depending on where you live. The assessor looks at your property's size, condition, location, and recent sales of similar homes in your area. Once the assessment is set, the tax rate (set by your city or county) is applied to that number to produce your tax bill.
Understanding how assessments work matters because they directly affect what you pay. If you think your assessment is too high, most places let you challenge it — but you need to know the process and the important date.
Key Takeaways
- A tax assessment is the dollar value your local assessor assigns to your property, separate from what it would sell for on the market.
- Assessments are used to calculate your property tax bill by multiplying the assessed value by your local tax rate.
- Most jurisdictions reassess property every one to five years, though some do it annually or on a longer cycle.
- You can usually challenge an assessment if you believe it is inaccurate, but you must do so within a specific window — often 30 to 60 days after you receive the notice.
How assessors determine your property's value
Assessors use several methods to arrive at a value. The most common is the sales comparison approach, where they look at recent sales of similar homes in your neighborhood and adjust for differences. If your house is smaller or in worse condition than a comparable home that sold nearby, your assessment will be lower.
For rental properties or commercial buildings, assessors may use the income approach, estimating value based on the income the property generates. For new construction or unusual properties, they may use the cost approach, calculating what it would cost to rebuild the structure from scratch, then subtracting for age and wear.
Assessors also look at public records: the size of your lot, the square footage of your home, the number of bedrooms and bathrooms, whether you have a garage or pool, and the age and condition of the structure. They may visit your property in person, though many jurisdictions now use photographs and aerial imagery instead.
The difference between assessment and market value
Your home's assessed value and its market value are often different numbers. Market value is what a buyer would actually pay for your home right now. Assessed value is what the government says it is worth for tax purposes, and it is usually lower.
In some states, assessments are capped at a percentage of market value — for example, 80 or 90 percent. In others, there is no cap, and assessments can drift further from reality if homes are not reassessed frequently. This is why two identical homes on the same street can have different tax bills: one may have been reassessed recently and the other not.
If you sell your home, the sale price becomes public record and may trigger a reassessment. This is one reason property taxes sometimes jump after a sale — the new assessment reflects the actual sale price rather than an older estimate.
When and how often assessments happen
The schedule for reassessment varies by location. Some counties reassess every year, others every three to five years, and a few only when property changes hands. Your county assessor's office can tell you the reassessment cycle in your area.
You will receive a notice when your property is reassessed. This notice includes the new assessed value, the date by which you can challenge it, and instructions for filing a challenge. The notice is usually mailed to the address on file, so if you have moved, make sure the assessor has your current mailing address.
Even if you do not receive a notice, you can request a copy of your assessment from the assessor's office. Many jurisdictions now post assessments online, searchable by address or parcel number.
How assessments affect your property tax bill
Your property tax bill is calculated with a straightforward formula: Assessed Value × Tax Rate = Property Tax Owed. If your assessed value is $300,000 and your tax rate is 1.2 percent, you owe $3,600 per year.
The tax rate is set by your city, county, and school district combined — it is not something the assessor controls. But the assessor controls the assessed value, which is why a higher assessment directly raises your bill. A $50,000 increase in assessed value at a 1.2 percent rate means an extra $600 per year in taxes.
Some states and localities offer exemptions or reductions for certain properties: homesteads, senior citizens, disabled veterans, agricultural land, or religious organizations. These exemptions reduce the assessed value or the tax rate, lowering the final bill. You usually have to request these exemptions separately from the assessor.
How to challenge an assessment you think is wrong
If you believe your assessment is too high, you can file a formal challenge, usually called an appeal or protest. The process and important date vary by state and county, but most places give you 30 to 60 days from the date you receive the assessment notice to file.
To build your case, gather evidence: recent appraisals, comparable sales in your neighborhood, photographs of any damage or needed repairs, and documentation of any errors in the assessor's records (wrong square footage, wrong number of bathrooms, or a garage listed that you do not have). If the assessor's data is straightforward wrong, that is often the easiest thing to fix.
You will typically file your appeal with the assessor's office or a local board of review. Some jurisdictions allow you to submit documents by mail; others require an in-person hearing. A few allow you to hire a property tax consultant or attorney to represent you, though this costs money and is usually only worth it for expensive properties.
What happens after you file an appeal
After you file, the assessor or board of review will review your evidence and may adjust the assessment. If they agree with you, your new assessed value will be lower and your future tax bills will reflect that. If they disagree, your assessment stays the same.
If you are unhappy with the result, most states allow a further appeal to a state tax court or board of appeals. This step is more formal and often requires legal representation, so it is less common for homeowners.
While your appeal is pending, you still owe property taxes based on the current assessment. If the appeal is successful and your assessment is reduced, you may receive a refund or credit for overpaid taxes, depending on your state's rules.
Frequently Asked Questions
Is my assessed value the same as my home's market value?
No. Assessed value is usually lower than market value because it is based on formulas and comparable sales, not an actual appraisal. In some states, assessments are capped at a percentage of market value. The two numbers can drift apart, especially if your home has not been reassessed in several years.
Can I lower my property taxes by lowering my assessed value?
Yes, if your assessment is inaccurate. Challenging an inflated assessment can reduce your tax bill. However, you cannot straightforward ask for a lower assessment without evidence — you need to show that the assessor made an error or that comparable homes are assessed lower than yours.
What should I bring to an assessment appeal hearing?
Bring evidence that the assessment is wrong: recent appraisals, comparable sales of similar homes in your area, photographs of damage or needed repairs, and documentation of any factual errors in the assessor's records (wrong square footage, missing or extra rooms). Keep copies for yourself and bring originals or certified copies for the board.
How long does it take to get a decision on an assessment appeal?
This varies by jurisdiction. Some boards decide within weeks; others take several months. Ask the assessor's office or board of review for their typical timeline when you file. Your property tax bill is usually due regardless of whether an appeal is pending.
Do I have to pay property taxes while my appeal is being decided?
Yes. You owe taxes based on the current assessment while your appeal is pending. If your appeal is successful and the assessment is reduced, you may receive a refund or credit for the overpaid amount, but the timing and method depend on your state's rules.