Assessed Value vs. Market Value: What the Difference Means for Your Tax Bill

Assessed value is the dollar figure a local government assigns to your property to calculate your property taxes, while market value is the price your property would likely sell for on the open market. The two numbers are set by different people for different purposes, and they are often not the same. Understanding the gap between them is the first step to knowing whether your property tax bill is fair.

The Short Version

• Market value answers the question: What would a willing buyer pay a willing seller today? It is driven by recent comparable sales, condition, location, and demand.
• Assessed value answers a narrower question: What value will the tax authority use to compute this year's bill? It is set by a county or municipal assessor and is often based on mass appraisal, not an individual sale.
• Your tax bill is generally calculated from the assessed value, not directly from what your home would sell for.

Because assessments can lag the market, rely on broad models, or apply a legal ratio, your assessed value can end up higher or lower than what your home is actually worth. When it is too high, you may be overpaying.

What Is Market Value?

Market value is an estimate of the price a property would fetch in an arm's-length sale between an informed buyer and an informed seller, with neither under pressure to act. It reflects real-world conditions:

• Recent sales of similar nearby properties ("comparables" or "comps")
• The property's size, age, condition, and features
• Location, neighborhood trends, and current buyer demand

Appraisers hired for a mortgage, a purchase, or a refinance estimate market value. So do real estate agents when they prepare a listing. Market value moves as the housing market moves.

What Is Assessed Value?

Assessed value is the figure your local assessor places on your property for tax purposes. Assessors typically use mass appraisal — statistical models applied across many properties at once — rather than walking through each home individually. Key things to know:

• Assessments are usually updated on a set cycle, which varies by jurisdiction. Some areas reassess every year; others do so less frequently.
• Many jurisdictions apply an assessment ratio, meaning the assessed value is a defined percentage of estimated market value rather than the full amount. The ratio, if any, is set by state or local law.
• Some places also apply caps, exemptions, or freezes that limit how much an assessment can rise in a given period.

Because of these mechanics, assessed value is a legal-administrative number, not a live sale price.

Why the Two Numbers Differ

Several structural reasons explain the gap:

1. Timing lag. Assessments reflect a valuation date that may be months or more before you receive the notice, so a fast-moving market can pull the two apart.
2. Mass appraisal error. Models estimate value for whole neighborhoods and can miss property-specific facts — a smaller lot, deferred maintenance, or an unfinished basement.
3. Assessment ratios. Where the assessed value is a percentage of market value, the raw numbers will look different by design.
4. Caps and exemptions. Legal limits can hold assessed value below market value for long-time owners, or create uneven results between neighbors.
5. Outdated records. Assessor data can list features, square footage, or condition that no longer match the actual property.

Any of these can mean your assessment overstates your home's true worth.

How Assessed Value Drives Your Tax Bill

At a high level, most property tax bills follow this pattern:

Assessed value − exemptions = taxable value. Taxable value × tax rate = your property tax.

The tax rate (sometimes expressed as a millage rate) is set by local taxing bodies and varies widely. Because the rate is applied to the assessed value, an inflated assessment inflates your bill even if the rate never changes. This is why homeowners focus on the assessed value when they think a bill is too high — it is the input they can challenge.

Note: Specific rates, ratios, exemptions, and reassessment schedules differ by state and county and change over time. Confirm the numbers that apply to you on your assessment notice or your county assessor's website.

How to Check Whether Your Assessment Is Fair

Use this quick checklist:

1. Find your assessed value. It is printed on your assessment notice and usually available on your county assessor's website.
2. Confirm the property record is accurate. Check square footage, bedroom/bath count, lot size, and condition. Errors here often inflate value.
3. Estimate your market value. Look at recent sales of similar homes near you, or get a professional appraisal or agent opinion.
4. Account for any assessment ratio. If your jurisdiction assesses at a percentage of market value, compare like with like — don't measure a ratio-based assessment against full market value.
5. Compare the numbers. If your assessed value (adjusted for any ratio) is meaningfully higher than a well-supported market value, you may have grounds to appeal.
6. Check your appeal window. Appeal deadlines are typically a set number of days from the date on your assessment notice. Read your notice and your assessor's site for the exact date and method.

Steps to Appeal an Over-Assessment

If your review suggests you are over-assessed, a typical appeal path looks like this:

1. Read your assessment notice carefully for the value, the valuation date, and the appeal instructions and deadline.
2. Gather evidence — comparable sales, a recent appraisal, photos of condition issues, and corrections to any factual errors in the property record.
3. File the appeal through the method your jurisdiction requires (online, by mail, or in person) before the stated deadline.
4. Present your case to the assessor or a review board, focusing on why the market value — and therefore the assessed value — should be lower.
5. Follow up. If the first-level decision is unfavorable, most jurisdictions offer at least one further level of appeal; the notice or assessor's office can explain your options.

Missing the deadline usually means waiting until the next cycle, so confirming your window early matters.

Key Takeaways

• Market value is what your home would sell for; assessed value is what your taxes are based on.
• The two differ because of timing, mass appraisal, assessment ratios, caps, and record errors.
• A higher-than-warranted assessed value raises your bill — and is the number you can appeal.
• Always verify rates, ratios, exemptions, and deadlines with your own notice and your county assessor, because these vary by location and change over time.