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.

How It Varies by State

TexasSales before Jan 1 of tax year

ARB considers sales from the prior 12-24 months. MLS data is commonly used. The CAD itself uses sales to build its appraisal models.

FloridaSales around Jan 1 assessment date

Value Adjustment Board (VAB) considers comparable sales. In non-disclosure states, sale prices may be harder to find.

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.

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.

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.

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.

Related Terms

Market Value Evidence Packet

Check Your Property

See if your property is overassessed and get your personalized evidence packet.

✓ All 50 states✓ Instant results✓ $49 flat fee