What Is Comparable Sales?

Recent sales of similar properties in the same area, used as evidence to establish a property's market value for tax appeal purposes.

Detailed Explanation

Comparable sales, or "comps," are the single most powerful piece of evidence in a property tax appeal. A comp is a recently sold property that is similar to yours in key characteristics: location, size, age, condition, and property type. When you present comps to the appeals board, you are saying, "These similar homes sold for less than what the county says my home is worth, so my assessment must be too high." The quality of your comps matters more than the quantity. A strong comparable sale is within half a mile of your property, sold within the last 6 to 12 months, has similar square footage (within 20%), was built within 10 years of your home, and has a similar number of bedrooms and bathrooms. Adjustments are often needed. If a comp has a pool and your home does not, or if a comp is 200 square feet larger, the sale price can be adjusted to account for the difference. Appeals boards are accustomed to seeing these adjustments and expect them. Finding comps requires access to sales data. County assessor websites, MLS records, and real estate platforms are common sources. Services like AppealDesk use property data APIs to identify the strongest comps automatically, saving homeowners hours of research. One complication that trips up homeowners in about a dozen states: so-called "non-disclosure states," where the actual sale price of a property is not required to be part of the public record at all. Texas, Kansas, Louisiana, and several other states fall into this category. In those states, county deed records show that a property changed hands but not what it sold for, so building a comp packet means leaning more heavily on MLS data, real estate platforms, or a service with access to non-public sales data, since the county courthouse alone will not get you there.

How It Varies by State

TexasSales before Jan 1 of tax year

ARB considers sales from the prior 12-24 months. Non-disclosure state, deed records do not show sale price, so MLS data is the primary source. The CAD itself uses sales to build its appraisal models.

FloridaSales around Jan 1 assessment date

Value Adjustment Board (VAB) considers comparable sales. Disclosure state, sale prices are part of the public deed record.

CaliforniaSales near Jan 1 lien date

Comps are used to challenge Prop 13 base year values or decline-in-value reassessments. Focus on sales close to the date of purchase.

IllinoisSales within 12 months of assessment

Board of Review uses comparable sales as primary evidence. Cook County has its own comp standards and adjustment methodology.

KansasNon-disclosure state

Like Texas, actual sale prices are not part of the public record. County appraisers and homeowners both rely on other data sources to build comps.

LouisianaNon-disclosure state

Sale prices are not publicly recorded. Combined with Louisiana's low assessment ratios, this makes independent verification of comps harder than in disclosure states.

Common Misconceptions

Myth:I need at least 5 comps to win an appeal

Reality:Three strong, well-matched comps are usually more persuasive than five mediocre ones. Quality over quantity. Even one excellent comp that is nearly identical to your property can carry weight.

Myth:Any recent sale nearby counts as a comparable

Reality:Comps must be genuinely similar. A new-construction luxury home is not comparable to a 30-year-old ranch even if they are on the same street. Significant differences in condition, size, or features weaken a comp.

Myth:Foreclosure and distressed sales cannot be used as comps

Reality:While some boards give less weight to distressed sales, they are not automatically excluded. If foreclosures represent a significant portion of your market, they reflect actual market conditions.

Myth:Sale prices are public record everywhere, so I can always look them up myself

Reality:About a dozen states, including Texas, Kansas, and Louisiana, are "non-disclosure" states where sale prices are not required to be recorded publicly. In those states, the county deed shows that a sale happened but not the price, so you need MLS access or another sales-data source to build a comp packet.

Impact on Your Tax Bill

Your home in Cook County, Illinois is assessed at $120,000 (implying $360,000 market value at the 33.33% ratio). You find three comparable sales at $310,000, $315,000, and $325,000, averaging $316,667. If the Board of Review agrees and lowers your implied market value to $316,667 (assessed value $105,556), at Cook County's average 2.1% effective rate, you save about $303 per year. In a non-disclosure state like Texas, the same math applies, but getting to those three sale prices in the first place typically requires MLS access rather than a courthouse records search.

Frequently Asked Questions

What is a non-disclosure state and why does it matter for comps?

A non-disclosure state is one where the actual price a property sold for is not required to be part of the public record. About a dozen states, including Texas, Kansas, and Louisiana, work this way. It matters for comps because you cannot simply pull sale prices from the county deed records, you need MLS access or another data source that captures actual transaction prices.

Can I use my own home's recent purchase price as a comp for itself?

Generally no, boards want independent comparable sales of other similar properties, not a circular reference to your own transaction. If you purchased recently below the assessed value, that purchase price itself can sometimes be submitted as direct evidence, but it is treated differently from a comp.

How many comps should I actually bring to a hearing?

Three well-matched, defensible comps typically outperform five weaker ones. Focus on proximity, recency, and similarity in size and condition rather than padding the count.

Do comps need to be adjusted for differences like a pool or extra square footage?

Yes, if a comp differs from your property in a material way, appeals boards expect a reasonable adjustment to the sale price to account for it. An unadjusted comp with an obvious difference is easier for the assessor's office to dismiss.

How to Use Comparable Sales in a Property Tax Appeal

How to Find Comparable Sales for Your Property Tax Appeal

Find the best comparable sales for your property tax appeal: 6 free and paid sources, what makes a strong comp, how many you need, and how to present evidence to your county.

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