What Evidence Do I Need for a Property Tax Appeal?

Most homeowners think appealing property taxes requires hiring an attorney or spending weeks researching obscure legal precedents. The reality is much simpler. Review boards evaluate appeals based on three categories of evidence, and if you have at least one strong category, your chances of winning are high.

According to the National Taxpayers Union Foundation, homeowners who file appeals with solid evidence win reductions 60-90% of the time. The key word is "solid"—here's exactly what that means.

Evidence Type #1: Comparable Sales Data (The Strongest Argument)

Comparable sales are the gold standard for property tax appeals. This is objective market data that proves what homes like yours are actually selling for—not what the county thinks they're worth. For a detailed ranking of all evidence types by effectiveness, see our guide on what's the best evidence to protest property taxes.

To build a strong comparable sales argument, you need 3-5 recent sales of properties that are:

• Similar in size — Within 10-20% of your home's square footage
• Similar in age — Built within 10-15 years of your home
• Similar in features — Same number of bedrooms/bathrooms, similar lot size, comparable condition
• Recently sold — Sold within the last 6-12 months (closer is better)
• Nearby — Within a half-mile radius if possible, same school district preferred

The critical factor: these comparable homes must have sold for less than your assessed value. If similar homes are selling for $380,000 but your home is assessed at $425,000, that's a $45,000 overassessment—and review boards understand this math immediately.

Where to Find Comparable Sales

You have several options for finding comparable sales data:

• County assessor websites — Most counties publish recent sales data online, though interfaces vary in quality
• Zillow, Redfin, Realtor.com — Free tools for finding recent sales, but you'll need to verify details against county records
• MLS access — Real estate agents have access to detailed MLS data if you know one willing to help
• Professional services — Companies like AppealDesk pull and format this data automatically

The DIY approach works, but it's time-consuming—expect to spend 8-15 hours researching, verifying, and formatting your comparable sales analysis. For detailed guidance, see our guide on finding comparable sales or our complete step-by-step DIY appeal guide.

Evidence Type #2: Property Condition Documentation

If your home has damage, needed repairs, or deferred maintenance that the county didn't account for, photo evidence can significantly strengthen your case.

Effective property condition evidence includes:

• Foundation issues — Cracks, settling, structural damage with repair estimates
• Roof damage — Missing shingles, leaks, age-related deterioration
• Water damage — Basement flooding, mold, drainage problems
• Deferred maintenance — Outdated HVAC, old water heater, worn flooring
• Functional obsolescence — Poor layout, single bathroom in a 3-bedroom home, no garage in an area where most homes have one

The key is documentation. Take clear, dated photos. Get contractor estimates for needed repairs. If your home needs a $15,000 roof replacement and the county assessed it as if the roof were new, that's strong evidence for a reduction.

This evidence works best when combined with comparable sales data. You're showing the review board: "Here's what similar homes in good condition sold for, and here's why mine is worth less than that due to these specific issues."

Evidence Type #3: Assessment Errors

County property records are surprisingly error-prone. If the assessor's data about your home is simply wrong, those errors are the easiest appeals to win because there's no subjective debate—either the facts are correct or they're not.

Common assessment errors include:

• Incorrect square footage — County records show 2,400 sq ft but your home is actually 2,100 sq ft
• Wrong bedroom/bathroom count — Listed as 4 bed / 3 bath when it's actually 3 bed / 2 bath
• Finished basement counted twice — Both as living space and as basement square footage
• Features you don't have — Assessed as having a pool, fireplace, or garage you don't actually have
• Lot size errors — Property records show 0.5 acres but your lot is 0.3 acres

To find these errors, request your property record card from your county assessor. This document lists all the data the county used to calculate your assessed value. Compare it line-by-line against your home's actual features.

If you find errors, provide proof: your home's blueprints, a professional appraisal, survey documents, or building permits showing the correct information. Review boards correct these mistakes quickly because they're factual errors, not valuation disagreements.

What Doesn't Count as Evidence

Many homeowners make the mistake of filing appeals based on arguments that review boards explicitly ignore:

• Zillow or Redfin estimates — Algorithmic valuations are not accepted as evidence. Only actual sale prices matter.
• "My taxes are too high" — Review boards evaluate assessed value, not tax bills. They don't have authority over tax rates or exemptions.
• "I can't afford to pay" — Personal financial hardship is not grounds for reducing your assessment.
• "My neighbor's assessment is lower" — Without comparable sales data showing your neighbor's home sold for less, this argument fails.
• Market value declined since purchase — Unless you can prove it with recent comparable sales, this is just opinion.

Stick to objective evidence: comparable sales, documented property condition issues, or factual errors in your property record. Everything else is noise that review boards filter out.

How to Present Your Evidence

Having strong evidence is only half the battle—you also need to present it clearly. Review boards see dozens or hundreds of appeals. The easier you make their job, the better your odds.

Effective presentation includes:

• A clear cover letter — One page stating your case: "I'm appealing because comparable sales show my home is overassessed by $X." For specific wording examples, see our guide on what to write when protesting property taxes.
• Organized documentation — Separate sections for comparable sales, property condition photos, and assessment errors.
• Comparison charts — Visual tables showing your home vs. comparable properties side-by-side.
• High-quality photos — Clear, well-lit images if you're documenting property condition issues.
• Supporting documents — Contractor estimates, survey documents, blueprints, or appraisal reports as needed.

Professional appeal services format evidence packets to match exactly what review boards expect. AppealDesk's $49 packet includes pre-formatted comparable sales analysis, county-specific filing instructions, and a cover letter template—everything organized the way review boards want to see it.

Bottom Line: Evidence Wins Appeals

The difference between winning and losing a property tax appeal almost always comes down to evidence quality. Homeowners who file with strong comparable sales data, documented property issues, or proof of assessment errors win most of the time. Those who file with weak evidence or emotional arguments lose.

The good news: gathering this evidence is straightforward if you know what review boards want. You can do it yourself in 8-15 hours, or you can use a service that pulls and formats everything automatically.

Either way, the evidence determines the outcome. Start with comparable sales data—it's the strongest argument and the one review boards respond to most consistently. If you're wondering whether your case is worth filing, see our analysis of whether appealing property taxes is worth it.