Property Tax Guide

What Evidence Actually Wins a Property Tax Appeal?

Published October 26, 2026

Homeowners who lose an appeal usually didn't have the wrong home. They had the wrong property tax appeal evidence. Boards hear dozens of cases a day, and they decide on one question: is the assessor's value for this property right? Evidence that answers that question wins. Evidence that answers a different one, like whether the tax is fair or affordable, almost never does.

The evidence that wins, strongest first

Evidence	What it proves	Why boards credit it
A factual error on your property record	The assessor valued a house you don't have	Hard to dispute: a survey or floor plan beats a data-entry mistake
Comparable sales	What buyers paid for homes like yours	It's the method assessors use for houses
Your own recent purchase	What your home sold for	A real arm's-length price for the exact property
An independent appraisal	A licensed professional's opinion of value	Sworn, methodical, and specific to your home
Condition evidence	Problems the assessor couldn't see	Photos and repair bids put a cost on defects
Uniformity evidence (where allowed)	Similar homes are assessed lower	Some states let you win on equal treatment alone

1. Errors on your property record

Start by pulling your property record card from the assessor's website. Check the square footage, bedroom and bathroom counts, basement finish, garage, lot size, and year built. Mass appraisal models run on this data, so one wrong field can push your value up without anyone noticing. The Cook County Board of Review lists "correction of factual error" as its own basis for appeal, with evidence such as a plat of survey, an architect's letter or drawings, or an appraisal showing the correct characteristics.

2. Comparable sales

Three or four recent, closed, arm's-length sales of truly similar homes nearby are the backbone of most residential wins. Our guide to comparable sales covers how to choose and adjust them.

3. Your own purchase price

If you bought recently in an ordinary market sale for less than the assessor's value, your closing documents are powerful evidence. The Cook County Board of Review accepts an arm's-length purchase within the past three years for less than the assessor's market value, supported by closing documents. A sale between relatives or a foreclosure won't carry the same weight.

4. An independent appraisal

Most homeowners don't need one, but an appraisal can be worth it on a higher-value home or a hard-to-compare property. In Texas it can also shift the burden. For a property valued at $1 million or less, a certified appraisal done no more than 180 days before the hearing and delivered to the chief appraiser at least 14 days before it raises the district's burden to clear and convincing evidence (Tex. Tax Code §41.43(a-1)).

5. Condition evidence

An assessor rarely sees inside your home. Dated photos of a failing roof, foundation cracks, or an original kitchen, plus written contractor estimates, show why your home is worth less than the neighbor's renovated one. A repair bid turns "it needs work" into a dollar figure.

6. Uniformity evidence

Some states let you argue that you're assessed higher than similar homes, even if your market value is right. Texas decides an unequal-appraisal protest for the owner unless the district shows your value is at or below the median of a reasonable number of comparable properties, appropriately adjusted (Tex. Tax Code §41.43(b)). The Cook County Board of Review accepts a "lack of uniformity" case built on assessment per square foot of similar homes in your neighborhood. See the Texas guide and the Illinois guide.

Evidence that doesn't win

• Your tax bill went up. Tax rates and budgets aren't on trial; your value is.
• You can't afford the tax. Hardship programs exist, but an appeal isn't one.
• A Zillow estimate or a listing price. Neither is a closed sale.
• A neighbor pays less on a different kind of house. Unless the homes are truly comparable and your state allows a uniformity claim, that's not evidence.

Know who has to prove what

The burden of proof changes how much you need. In most Texas value protests the appraisal district must establish the value by a preponderance of the evidence, or the owner wins (Tex. Tax Code §41.43(a)). Florida runs the other way. Once the property appraiser shows the assessment was made under the law and accepted appraisal practices, it's presumed correct, and you must prove by a preponderance of the evidence that it isn't just value (Fla. Stat. §194.301). See the Florida guide. Rules differ in every state, so check your state's guide first. It also covers your deadline and whether the board can raise your value.

Put it together

1. Fix the facts first. A record error is the quickest win there is.
2. Lead with value evidence. Use comps, your purchase price, or an appraisal, plus condition proof for anything the assessor missed.
3. Make the math easy. Show the board one clear number and how you got it. If you aren't sure the gap is real, start with our over-assessment check.

PROppeal builds this case for you. It pulls recent sales near your address, applies your state's rules, and tells you plainly whether the evidence supports an appeal, including when it doesn't.

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