How to Find Comps for a Property Tax Appeal (Any State, 2026)

Nearly every property tax appeal is won or lost on comparable properties, and most homeowners bring the wrong kind.

There are two distinct types of comps, they support two different legal arguments, and in some states one of them is nearly impossible for a homeowner to obtain while the other is free and public. Bringing five Zillow listings to a hearing is the most common way a legitimate over-assessment gets denied.

This guide covers both types: where to get them free in any state, how to screen out the ones that will get your case thrown out, how to adjust for differences, and how to assemble a table a review board can act on.

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The two kinds of comps, and which argument each supports

Sale comps: proving market value

What they are: recent arm's length sales of similar properties near you.

What they prove: that your property's market value is lower than the assessor says.

Where they come from: recorded deeds, MLS data, and your county's sales records.

Assessment comps: proving unequal treatment

What they are: the assessor's own current values on similar properties near you. Not sales. Assessments.

What they prove: that your property is being valued differently from comparable properties, regardless of what anyone's house is truly worth.

Where they come from: your county assessor's public property search, free, for every parcel in the county.

The distinction is decisive for two reasons.

First, availability. About a dozen states are non-disclosure states, where sale prices are not recorded in public records at all. Texas is the most consequential of these. A homeowner in Houston cannot simply look up what the house down the street sold for, because that price is not public. Meanwhile, every assessed value in the county is public and searchable. In a non-disclosure state, assessment comps are not the fallback. They are the primary tool.

Second, legal standing. Several states make uniformity an independent ground for appeal. Texas is the clearest: you may protest either that the value exceeds market value, or that your property is appraised unequally compared with a reasonable number of comparable properties, appropriately adjusted. Those are separate arguments and you can raise both. Winning the unequal appraisal argument does not require proving what your home is worth at all. New Jersey's Chapter 123 common level range and Pennsylvania's Common Level Ratio mechanism perform a related function, converting between assessed and market value at a published ratio.

Practical rule: in a non-disclosure state, lead with assessment comps. Everywhere else, bring both, because a board that is unconvinced by one may be convinced by the other.

Where to get comps, free

Your county assessor's property search. Start here in every state. Nearly every assessor publishes a parcel search with assessed value, square footage, year built, bed and bath count, lot size, and often the property card. This is the source for assessment comps, and it is authoritative, because it is the county's own data. When you cite it, the county cannot argue the numbers are unreliable without undermining itself.

County recorder or clerk deed records. In disclosure states, recorded deeds carry the sale price. Searchable online in most counties.

Your state's sales or ratio study data. Many revenue departments publish validated sales files used for equalization studies. These are pre-screened for arm's length transactions, which does the hardest part of the work for you.

A real estate agent. Many will pull MLS comps for free. MLS carries verified closing prices, condition notes, and days on market. If you use this route, ask for closed sales, not active listings.

What not to rely on. Zillow Zestimates, Redfin Estimates, and similar automated valuations are themselves model outputs, not evidence, and boards discount them heavily. A Zestimate is one algorithm's opinion offered to rebut another algorithm's opinion. Use those sites to find addresses of nearby sales, then verify the actual sale price and details in county records, and cite the county record.

The screening rules

A comp that does not survive scrutiny is worse than no comp, because it invites the assessor to attack your whole submission. Screen hard.

Similarity

• Square footage within about 15%. This is the tightest constraint and the one that matters most, because value per square foot is how most of this analysis is done.
• Year built within about 10 years. Age drives depreciation schedules and buyer perception.
• Same property type and style. A single-story ranch is not comparable to a two-story of identical square footage.
• Similar lot size, especially where lots vary meaningfully.
• Same bed and bath count, or within one.

Location

• Same subdivision or appraisal neighborhood if possible. Many counties assign a neighborhood code on the property card. Matching that code is the strongest locational argument available, because it is the county's own definition of "comparable area."
• Same school district and same taxing jurisdictions. Crossing a school boundary introduces a value difference an assessor will immediately point out.
• Within about half a mile in a suburb, closer in a dense urban area.

Time (sale comps only)

• As close to your assessment date as possible. Most states value as of January 1. A sale from eleven months after the assessment date reflects a different market.
• Within 6 to 12 months of the assessment date is the usual acceptable range.

Sales you must exclude

These are not arm's length transactions and citing them damages your credibility:

• Foreclosures, REO sales, and short sales
• Auction sales
• Transfers between family members
• Estate and probate sales under time pressure
• Transfers between related business entities
• New construction sold with builder incentives, rate buydowns, or closing cost credits
• Sales including significant personal property or seller concessions
• Any transfer recorded for a nominal amount ($1, $10, "love and affection")

If a sale looks unusually low, there is usually a reason, and the assessor knows it. Leaving it out strengthens everything else you present.

The screening is the tedious part. AppealMyTax applies these similarity filters against real county roll data automatically and returns the comparable properties with the value gap already calculated. Free to see the result. The $49 report gives you the full comparison as a filing-ready PDF, flat fee, never a percentage of your savings. Pull my comps →

Adjusting comps

No two houses are identical. Boards expect you to account for differences, and a table showing adjustments reads as competent rather than opportunistic.

The simplest defensible method is value per square foot, which normalizes the single largest difference automatically:

1. For each comp, divide the value (assessed value for assessment comps, sale price for sale comps) by its square footage.
2. Take the median of your comps.
3. Multiply that median by your square footage.
4. That product is your supported value.

Worked example:

Supported value: 2,100 x $167 = $350,700. Your assessment is $395,000. The gap is $44,300, about 12.6% above what comparable homes in the same neighborhood are carrying. At a 2% effective tax rate that is roughly $886 a year, every year, until it is corrected.

That table is the entire argument. It fits on one page, every number is checkable against county records, and it makes the assessor's position the one that needs explaining.

For material differences the per-square-foot method does not capture (your comp has a pool and you do not, or a garage you lack), make a specific dollar adjustment and label it. Keep adjustments conservative and few. A table with three modest, clearly explained adjustments is far more persuasive than one with fifteen precise-looking ones you cannot defend under questioning.

How many comps?

Five to eight is the target. Fewer than three looks cherry-picked. More than ten dilutes your strongest evidence and gives the assessor more surface to attack.

Some states define the test directly. Under Texas Tax Code Section 41.43(b)(3), an unequal appraisal protest is determined in the owner's favor if the appraised value exceeds the median appraised value of a reasonable number of comparable properties, appropriately adjusted. That is exactly the calculation in the table above, and it is why you take the median rather than the average: one unusually low comp cannot carry your case, and one unusually high one cannot sink it. The statute also requires that the selection of comparables and the adjustments be based on generally accepted appraisal methods, which is the standard the screening rules above are built to meet. In practice five or more comps is the working floor for a residential protest.

Choose the comps that are genuinely most similar, not the ones with the lowest values. If your five best comps do not support a reduction, you are probably fairly assessed, and that is worth knowing before you spend a day on a hearing.

Presenting it

• Lead with one page. The comp table, your supported value, and the requested value. Everything else is backup.
• Cite the source for every number. "Assessed values from [County] Assessor property search, retrieved [date]." Verifiability is what separates evidence from assertion.
• Include the property card corrections separately, if you found any in your record. Factual errors are the fastest wins and often get fixed informally without a hearing.
• State a specific requested value. Not "lower." A number, supported by your table.
• Bring photos for condition issues the model cannot see, dated and captioned.

What is the difference between sale comps and assessment comps?

Sale comps are recent arm's length sales of similar properties, used to prove your home's market value is lower than the assessor's estimate. Assessment comps are the assessor's own current values on similar nearby properties, used to prove your property is being treated differently from comparable ones. In non-disclosure states like Texas, sale prices are not public, so assessment comps are the primary tool available to a homeowner, and several states treat unequal assessment as an independent legal ground for appeal.

Can I use Zillow comps for a property tax appeal?

Use Zillow or Redfin to locate nearby sales, but do not submit their estimates as evidence. An automated valuation is a model output, and offering one model's opinion to rebut another model's opinion carries little weight with a review board. Verify each address in your county's official records and cite the county record, the recorded sale price, or the MLS closing data instead.

Know your deadline first

Comps take a few hours to assemble properly. Appeal windows are short and strictly enforced, and they differ substantially: Texas is generally May 15 or 30 days after your notice; Florida is 25 days after the TRIM notice mails; Georgia is 45 days from the notice date; Illinois runs township by township with no statewide date; Pennsylvania is commonly September 1 for the following year. Confirm yours on the relevant state guide before you start gathering.

The shortcut

Assembling comps by hand takes a few hours and access to records that, in non-disclosure states, are not fully public. That is the friction we removed.

AppealMyTax finds your parcel in 22.7 million real county records, applies the similarity screening above, and shows you the comparable properties and the value gap before you pay anything. If your comps do not support a reduction, you will see that too, and you should not buy anything.

If they do, the $49 report delivers the full comparison, the supported value, and the evidence in a filing-ready PDF. One flat fee, one time, never a percentage of your savings. You keep 100% of what you win. Compare that to a contingency service taking 25% to 50% of your first-year savings, every year, as our Ownwell comparison breaks down.

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This guide is general information, not legal or tax advice. Evidence standards, comp requirements, and deadlines vary by state and county. Verify your jurisdiction's rules with your assessor or review board before filing.

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