10 Signs Your Property is Over-Assessed

Most homeowners assume their property tax assessment is roughly accurate. It usually isn't. County assessors value thousands of properties at once using mass appraisal models — statistical shortcuts that miss the specifics of your house. Studies from the Lincoln Institute of Land Policy suggest that 30 to 60 percent of residential properties are over-assessed in any given year, depending on the jurisdiction.

The good news is that spotting over-assessment is easier than most people think. Here are the ten clearest warning signs, and exactly what to do about each one.

1. Your assessed value jumped more than 10 percent while the market stayed flat

This is the single biggest red flag. If Zillow, Redfin, and your local MLS all show neighborhood prices holding steady — or declining — but your assessment went up double digits, the assessor's model is out of sync with reality. Pull your last three years of assessment notices and plot the change against Case-Shiller or your county's own median sale price. A widening gap is evidence you can bring to a hearing. Save screenshots of neighborhood price trends with dates visible.

2. Recent comparable sales in your neighborhood are selling for less

This is the most direct evidence of over-assessment and the backbone of almost every winning protest. Look for three to five homes sold in the last six to twelve months within a half mile of yours, similar in size (within 20 percent), age, and condition. If their sale prices average below your assessed value, you have a textbook market-value case. Document each comp with the MLS listing, sale price, sale date, and a photo. Most counties require closed sales, not active listings.

3. Your square footage is wrong on the assessment

Assessors often rely on old building permits, aerial photos, or drive-by surveys. Errors of 100 to 500 square feet are common, and every extra foot inflates your value. Measure your home's interior yourself — exterior walls from corner to corner for each conditioned room — and compare the total against the square footage printed on your assessment notice. If the county says 2,400 sq ft and you measure 2,150, that's a 10 percent overstatement you can prove with a tape measure and a diagram. Bring your sketch, measurements, and photos to the hearing.

4. Your bedroom or bathroom count is incorrect

Mass appraisal models weight bedrooms and bathrooms heavily. If the assessor listed four bedrooms but you only have three, or counted a half-bath as a full, your value is inflated. Check your property record card (usually available on the county assessor's website) and compare it against reality. Photograph every room and fixture. A missing bathroom alone can knock 3 to 5 percent off your assessed value.

5. Your property has damage or deferred maintenance not reflected in the value

Assessors typically value homes in "average" condition. If yours has a leaking roof, foundation cracks, water damage, failing HVAC, outdated electrical, or an unusable kitchen, you are being taxed as if those problems don't exist. Get repair estimates from licensed contractors — these are gold at a hearing. Photograph every defect with timestamps. A $25,000 foundation repair estimate on a $400,000 home is a direct argument for a $25,000 reduction in market value.

6. Similar neighbors pay less tax

This is the equity argument, and it's especially powerful in Texas, Georgia, and other states that legally protect uniform assessment. Pull the assessed values of five to ten nearby homes that are similar in size, age, and style. If your per-square-foot assessment is noticeably higher than theirs, you can argue you're being treated unequally even if your market value is defensible. Most assessor websites let you search neighboring parcels for free. Screenshot the evidence.

7. Your assessment didn't decrease after a major market downturn

Assessments are supposed to track the market both up and down. After events like the 2022-2023 interest rate shock, many counties were slow to reduce values. If your market dropped 8 percent but your assessment held flat or rose, that's a strong case. Compare the county's claimed value trend against independent sources — Zillow Research, Redfin Data Center, or your local Realtors' association reports.

8. You bought the house recently for less than the assessed value

If you purchased the home within the last twelve to eighteen months in an arm's-length transaction (meaning between unrelated parties, not a family transfer or foreclosure), that sale price is legally considered the best evidence of market value in most jurisdictions. Bring the closing disclosure, HUD-1, or settlement statement. If you paid $380,000 and the county is assessing at $425,000, the math is on your side and the hearing is usually brief.

9. The assessor listed the wrong property type or use

Classification errors are surprisingly common, especially at the residential-commercial border. A home office on the record as "mixed use," a duplex listed as a small apartment building, or a single-family listed as "multifamily" can all trigger commercial tax rates that are far higher. Check the "property use" or "class code" on your assessment notice. If it's wrong, a classification correction alone can cut your bill by 20 percent or more without touching the valuation.

10. Your lot size or land area is wrong

Land value is a significant chunk of most assessments, and assessors sometimes use outdated plat data. Pull the plat map from the county recorder and compare the recorded square footage or acreage against what the assessor has on file. A discrepancy of even a tenth of an acre can matter in high-value neighborhoods. The fix is clerical — bring the recorded plat and ask for a correction.

What to do next

Most homeowners who take a hard look find at least one of these issues. That's all it takes. You do not need a perfect case, and you do not need to prove every error. A single documented sign — wrong square footage, a recent low sale, a damaged roof — is often enough to win a reduction.

The math is worth the effort. A 10 percent reduction on a $400,000 assessment saves the typical homeowner between $600 and $1,000 per year, depending on the state and local tax rate. In Texas, New Jersey, and Illinois, it can be more. Over a decade of ownership, that's real money.

Before you start gathering evidence yourself, run your property through ProtestMax's free 60-second check. We'll pull your assessment, compare it against recent sales and neighbor data, and give you an evidence grade (A through F) so you know whether it's worth filing a protest at all. If the grade is strong, we'll build your entire protest packet for you.