Property Tax Guide

Is My Home Over-Assessed? How to Tell in 5 Minutes

Published September 8, 2026

Most homeowners look at a property tax bill, decide it feels high, and stop there. That is not enough to appeal on — but "is my home over-assessed?" has a real answer, and you can get most of the way to it in about five minutes with your assessment notice and a browser tab.

The short version: your home is over-assessed when the market value your county implied — the assessed value on your notice divided by your state's assessment ratio — is meaningfully higher than what comparable homes near you actually sold for in the past year. Everything below is how to get each of those two numbers right.

#	The check	What you need
1	Find the assessed value your county actually used	Your assessment notice
2	Convert it to the market value the county implied	Your state's assessment ratio
3	Find three or four homes like yours that sold	Closed sales, last 12 months
4	Compare on price per square foot, then adjust	Beds, baths, age, condition, lot
5	Decide whether the gap is big enough to argue	The size of the gap

Step 1: Assessed value vs. market value — find the number the county used

Your notice carries at least two numbers, and they are not interchangeable. The appraised (or market, or full, or actual) value is what the county believes your home would sell for. The assessed (or taxable) value is the figure your tax rate is actually applied to. In some states those are the same number. In many others the assessed value is a set fraction of market value, and in some it has been held down for years by a growth cap.

Find the appraisal year too. An assessment is a snapshot as of a specific valuation date, and a notice you open in the fall may be reporting what the county thought your home was worth many months earlier. You have to compare sales to that date, not to today.

Step 2: Convert the assessed value back to market value

If your state assesses at a fraction of market value, divide to get the number the county is really claiming. An assessed value of $50,000 in a state with a 20% assessment ratio implies a market value of $250,000 — and that $250,000 is what you are arguing about, not the $50,000.

This is the step most homeowners skip, and skipping it produces confident nonsense in both directions: people panic at a full-value number that is actually a fraction, or they compare a fractional assessed value straight to sale prices and conclude they are getting a bargain. Get the ratio right first. Ratios are set by state law and differ sharply — Texas and Florida assess on full market value, while Arkansas and South Carolina tax a fraction of it. Your state's property tax appeal guide carries the ratio and its statutory basis.

Step 3: Use comparable sales, not listings

The evidence that moves a board is closed sales — homes that actually changed hands, near you, recently, that resemble yours. Listing prices are asking prices, and an automated home-value estimate is a model output that no board is obligated to credit. Three or four real comparable sales beat a page of screenshots.

Aim for sales within the last year, in your neighborhood or a genuinely similar one, in the same property type and roughly the same size. A sale a mile away in a different school attendance area is not a comparable just because the square footage matches.

Step 4: Compare price per square foot, then adjust

Divide each sale price by that home's finished square footage to get a price per square foot, and do the same for the county's implied market value of your home. If the county's figure per square foot sits above every real sale you can find, that gap is your case in one line.

Then adjust for what the raw number hides. A comp with a finished basement, a recent kitchen, an extra bathroom, or a third garage bay should sell for more than yours, and that difference belongs to the comp, not to you. Adjusting against yourself is what makes an appeal credible — a board that can see you gave away the points you should have given away will take the rest of your numbers more seriously.

Step 5: Is the gap big enough to file a property tax appeal?

Mass appraisal is a statistical exercise across thousands of parcels, and the professional standard for it says plainly that ratio statistics measure the overall level of assessment and cannot judge the accuracy of any single parcel. Individual homes vary around that level by design. A gap of a few percent sits inside that normal margin and rarely survives a hearing. A gap in the low double digits, supported by comps you can defend one at a time, is the range where an appeal has something real to argue.

The size of the gap also tells you what a win is worth. Multiply the reduction you think you can prove by your total tax rate to get the annual savings — that is the number to weigh against the filing fee and an afternoon of your time.

What a 5-minute check can't tell you

This check answers whether your value looks wrong. It does not answer whether filing is a good idea, and three things decide that:

• Your appeal deadline. Filing windows are set by state law and are often keyed to the date your notice was mailed, so they move by county and by year. Miss it and the value is locked in for the cycle no matter how good your comps are.
• Your assessment cap. Several states cap how much a taxable value can rise each year. If a cap is already holding your taxable value below market, proving a lower market value may protect your future baseline without cutting this year's bill.
• Whether the board can raise you. In most states the board reviewing your appeal can move the value up as well as down. In a smaller group — New York and Texas among them — statute bars the board from raising you on your own appeal. This is state law, it is knowable before you file, and it should be the last thing you check.

All three turn on where you live. Pick your state from the state-by-state property tax appeal guides for the ratio, the deadline, the cap, and the raise rule together.

When the honest answer is "you're assessed fairly"

Run this check and some homes come out fine — the county's implied market value lands inside the range of what comparable homes actually sold for. That is a useful result. It costs nothing, it closes a nagging question, and it saves you from walking into a hearing with an argument the sales do not support.

PROppeal runs exactly this analysis with licensed comparable sales for your address, applies your state's ratio and cap rules, and tells you which of the two answers you have — including when the answer is that you do not have a case.

Property tax rules and deadlines vary by jurisdiction and can change — verify with your county before relying on this.