How to Use Comparable Sales to Lower Your Property Taxes

If you are protesting your property tax assessment, the single most persuasive piece of evidence you can present is a set of comparable sales, commonly called "comps." Appraisal review boards and county assessors base their valuations on what similar properties have actually sold for. If you can show that comparable homes sold for less than your assessed value, you have a strong case for a reduction.

1. What Are Comparable Sales?

Comparable sales are recent transactions of properties that are similar to yours in key characteristics. The most important factors are:

• Location: Ideally within a half-mile of your property, in the same neighborhood or school district.
• Size: Within 20 percent of your home's square footage.
• Age: Built within 10 years of your home, or recently renovated to a similar standard.
• Bedrooms and bathrooms: The same count, or within one.
• Condition: Similar maintenance level. A remodeled home is not comparable to one with deferred maintenance.
• Sale date: Sold within the past 6 to 12 months, ideally before the assessment date.

The closer a comparable is to your property on each of these dimensions, the more weight it carries with the review board.

2. How Assessors Use Comparable Sales

County appraisal districts use mass appraisal methods to value thousands of properties at once. They build statistical models based on recent sales in each area, then apply those models broadly. The problem is that mass appraisal can miss individual property characteristics. Your home may be on a busy road, have a smaller lot, back up to commercial property, or have condition issues that the model does not account for.

When you file a protest, the assessor will present their own comparable sales to justify your valuation. Your job is to present better comps, ones that are more similar to your property and that sold for less.

3. How to Find Your Own Comparable Sales

There are several ways to find comparable sales for your property tax protest:

• County appraisal district website: Most districts publish a property search tool where you can look up recent sales and assessed values for properties in your area.
• MLS data (via a real estate agent): If you have a relationship with a real estate agent, they can pull recent sales data from the Multiple Listing Service, which includes listing photos, sale dates, and detailed property information.
• Public records sites: Websites like your county clerk's office or state property data portals often list recent deed transfers with sale prices.
• Real estate websites: Zillow, Redfin, and Realtor.com show recent sales with basic property details. However, they may not include all the data you need for adjustments.

When selecting comps, choose properties that support your case. If a comparable sold for more than your assessed value, leave it out. You are not obligated to present evidence against yourself. Focus on the 3 to 5 most similar properties that sold for the lowest prices.

4. Making Adjustments to Comparable Sales

No two properties are identical. When a comparable differs from your property, you need to adjust its sale price to account for the difference. Common adjustments include:

• A comparable has a pool and yours does not: subtract the pool's estimated value from the comp's sale price.
• A comparable is 200 square feet larger: subtract the value of those extra square feet based on the local price per square foot.
• A comparable sold six months ago in a declining market: adjust downward for market conditions.

After adjustments, the comps should reflect what your property would sell for in its current condition. If the adjusted value of comparable sales is lower than your assessment, you have evidence of over-assessment.

5. Why ProtestMax Makes This Easier

Finding, filtering, and adjusting comparable sales is time-consuming and requires access to reliable data. ProtestMax automates the entire process:

• AI searches property databases for the most relevant comparable sales near your property.
• Each comp is automatically adjusted for differences in size, age, condition, and features.
• The system generates a professional evidence packet with charts, tables, and a written summary ready to present at your hearing.
• Everything is formatted to meet your county's submission requirements.

Related Guides

• How to Protest Your Property Taxes: A Step-by-Step Guide (2026)
• Is Your Property Tax Assessment Too High? Here's How to Check
• Property Tax Protest Deadlines by State (2026)