Before you spend an afternoon assembling an appeal, it is worth ten minutes to find out whether you have a case at all. Assessors value huge numbers of homes with formulas rather than visits, so errors are common, but plenty of assessments are perfectly fair. These two tests separate the two.
First, find your assessed market value
Pull out your latest assessment notice or look up your property on the county assessor's website. You are looking for the value the assessor has placed on your home. This can be labeled a few ways, and the label matters:
- Market value or appraised value: the assessor's estimate of what your home is worth. This is the number to test against a real sale price.
- Assessed value or taxable value: often a fraction of market value, because many states tax only a percentage of the full value. Do not compare this directly to a sale price without adjusting for the ratio first.
The distinction trips up a lot of homeowners, and it is important enough that we cover it in its own guide: assessed value vs market value. For this test, you want the assessor's estimate of full market value.
Test 1: The market-value test
The core question: would your home sell for less than the assessor says it is worth? If yes, you are over-assessed on value, which is the most common and most winnable ground for appeal.
To estimate what your home would sell for, look at recent sales of similar homes near you. You want arm's-length sales (not transfers between family, foreclosures, or estate sales) from roughly the last year, of homes close in size, age, condition, and location. Take a handful of those sale prices and compare the middle of that range to your assessed market value.
Be honest about condition. If your home is genuinely nicer, larger, or better located than the comps, adjust for that before concluding you are over-assessed. The board will.
Test 2: The uniformity test
Even if your assessed value looks close to market, you can still be over-assessed relative to your neighbors. This is the uniformity or equity argument, and how much it matters depends heavily on your state.
The idea: property tax is supposed to be applied evenly. If comparable homes in your area are assessed at, say, 85% of their market value and yours is assessed at 100%, you are carrying more than your fair share even if your raw number is defensible. To check, compare the assessment ratio (assessed value divided by likely market value) of a few similar nearby homes to your own. Assessor records are public, so you can look up what your neighbors are assessed at.
Signs your property record itself is wrong
Sometimes the assessment is high because the underlying facts are wrong. Pull your property record card from the assessor (usually public) and check the details:
- Square footage larger than reality.
- Bedroom or bathroom count too high.
- A finished basement or attic counted as living space when it is not.
- Lot size overstated.
- Condition or quality grade that does not match the actual state of the home.
A factual error is one of the easiest appeals to win, because you are not arguing opinion, you are correcting a record. Photos and measurements usually settle it.
How big does the gap need to be?
There is no universal threshold, but it helps to think in dollars, not just percentages. Multiply the over-assessment gap by your local effective tax rate to see the annual savings at stake. A $54,000 over-assessment at a 1.35% effective rate is roughly $729 a year, and if a reduction carries forward until the next reassessment, that is several years of savings for one afternoon of work. A gap of a few thousand dollars, on the other hand, may not be worth the effort, and a board may not move for it.
When you are probably not over-assessed
It is worth knowing the honest negative signals too, so you do not waste an appeal:
- Your assessed market value is at or below recent comparable sales.
- You bought the home recently, at arm's length, for around the assessed value.
- Your assessment ratio is in line with comparable homes nearby.
- Your property record is accurate.
If all four are true, an appeal is unlikely to succeed, and knowing your assessment is fair is itself worth the ten minutes.
The short version
Compare the assessor's market value to what similar homes actually sold for. If your value is meaningfully higher, you are over-assessed and have a case. Then double-check your property record for factual errors and, where your state cares about it, compare your assessment ratio to your neighbors'. Put a dollar figure on the gap before you decide it is worth appealing.
Get both tests run for your address.
The report estimates your home's market value, reads your assessed value, works out the gap and the annual overpayment, and pulls the comps, so you can see at a glance whether an appeal is worth filing.
Get your Property Tax Appeal Report · $29