How to Find Comparable Sales for Your Property Tax Appeal: Complete Guide
TL;DR
Comparable sales are the single most important piece of evidence in a property tax appeal. Find 3-5 homes similar to yours that sold within the last 6-12 months and within 1 mile. Use your county assessor website, Zillow, Redfin, and MLS data from a real estate agent. Adjust for differences in size, condition, lot, and features. Present them in a comparison table showing that your assessed value exceeds what the market actually supports.
Why Comparable Sales Win Appeals
Assessors set your property value using comparable sales. When you appeal, the review board wants to see the same type of evidence. If you can show that similar homes in your area sold for less than your assessed value, you have a strong case. Every other type of evidence, from photos to repair estimates, supports this central argument.
The typical successful appeal includes 3-5 well-chosen comparable sales. Fewer than three looks thin. More than seven starts to dilute the impact. Quality matters more than quantity.
Where to Find Comparable Sales
Free Sources
County assessor website. Your best starting point. Most counties publish recent sales with prices, dates, and property details. This data is official, which means the review board cannot question its source. Search by your neighborhood or zip code and filter for sales in the last 12 months.
Zillow. Search your address, then use the "Recently Sold" map filter. Zillow shows sale prices, dates, photos, square footage, beds, baths, and lot size. The data comes from public records with a short lag.
Redfin. Often more current than Zillow because it pulls from the MLS in many markets. Use the "Sold" filter and draw a boundary around your neighborhood. Redfin also calculates price per square foot, which is useful for adjustments.
Realtor.com. Another reliable source with sold data going back several years. Good for establishing longer-term price trends.
Professional Sources
Real estate agent. Many agents will pull MLS comparable sales for free, especially if you know them or they hope to earn your business later. MLS data is the most detailed and current available.
County recorder's office. For official deed records with exact transfer prices. Most authoritative but harder to search.
Professional appraisal. An appraiser will select comps, make adjustments, and deliver a certified value opinion. Costs $300-$500 but carries significant weight with review boards. See our guide on independent appraisals for tax appeals.
What Makes a Good Comparable
Not every recent sale qualifies. The review board will scrutinize each comp you present. Here is what makes a sale genuinely comparable:
| Factor | Ideal | Acceptable | Weak |
|---|---|---|---|
| Sale date | Last 6 months | Last 12 months | Over 12 months |
| Distance | Same subdivision | Within 1 mile | Over 1 mile |
| Square footage | Within 10% | Within 20% | Over 20% |
| Year built | Within 5 years | Within 15 years | Over 15 years |
| Style | Same type | Similar type | Different type |
| Beds/baths | Same count | Within 1 | Off by 2+ |
| Lot size | Within 10% | Within 25% | Over 25% |
Sales to Exclude
Only use arm's-length transactions. Exclude:
- Foreclosures and bank-owned sales
- Short sales
- Family member transfers
- Estate sales under time pressure
- Auction sales
- Corporate relocations
- Sales with seller concessions that distort the price
How to Select the Strongest Comps
Step 1: Build Your Pool
Pull all sales within 1 mile from the last 12 months. Filter for homes within 20% of your square footage and within 15 years of your home's age. This gives you the raw pool.
Step 2: Score Each Sale
Rank each sale by overall similarity. The best comp matches your home on every factor. In practice, weigh proximity and sale date most heavily. A very similar home that sold last month carries more weight than a decent match from 10 months ago.
Step 3: Pick the Best 3-5
Select the sales that are most similar to your property AND sold for less than your assessed value. If a nearly identical home sold for more than your assessment, leave it out. The assessor will find it on their own.
Step 4: Verify Details
Before finalizing, check each comp for accuracy. Verify the sale price against county records. Confirm the property details are correct. Make sure the sale was arm's-length.
Making Adjustments
No two homes are identical. You need to adjust each comp's sale price to account for differences. Common adjustments:
- Size. Calculate price per square foot from the comp, then adjust for the size difference. If the comp sold at $180/sqft and is 100 sqft larger than your home, adjust down by $18,000.
- Features. Pool ($15,000-$30,000), extra garage bay ($10,000-$20,000), finished basement ($20,000-$40,000).
- Condition. A renovated comp should be adjusted down if your home has not been updated.
- Lot size. Larger lots command higher prices. Adjust proportionally based on local land values.
- Age. Newer homes typically sell for more per square foot than older ones.
Keep adjustments reasonable. A comp requiring more than 25% in adjustments is probably not comparable enough to use.
Presenting Your Comps
Use a clean comparison table. The review board sees dozens of cases. Make yours easy to follow.
| Detail | Your Home | Comp 1 | Comp 2 | Comp 3 |
|---|---|---|---|---|
| Address | 123 Main St | 456 Oak Ave | 789 Elm Dr | 321 Pine Ln |
| Sale price | Assessed $380K | $335,000 | $328,000 | $340,000 |
| Sq ft | 2,100 | 2,050 | 2,200 | 2,080 |
| Adjusted price | - | $338,000 | $322,000 | $341,000 |
Below the table, write a brief paragraph summarizing: "The average adjusted sale price of these comparable properties is $333,667, which is 12% below the current assessed value of $380,000."
For more on structuring your entire evidence package, see our evidence guide.
Frequently Asked Questions
How to Find Comparable Sales for Your Property Tax Appeal: Complete Guide?
Comparable sales are the single most important piece of evidence in a property tax appeal. Find 3-5 homes similar to yours that sold within the last 6-12 months and within 1 mile. Use your county assessor website, Zillow, Redfin, and MLS data from a real estate agent.
Why Comparable Sales Win Appeals?
Assessors set your property value using comparable sales. When you appeal, the review board wants to see the same type of evidence. If you can show that similar homes in your area sold for less than your assessed value, you have a strong case.
Where to Find Comparable Sales?
County assessor website. Your best starting point. Most counties publish recent sales with prices, dates, and property details.
What Makes a Good Comparable?
Not every recent sale qualifies. The review board will scrutinize each comp you present. Here is what makes a sale genuinely comparable:
How to Select the Strongest Comps?
Pull all sales within 1 mile from the last 12 months. Filter for homes within 20% of your square footage and within 15 years of your home's age. This gives you the raw pool.
What should I know about making adjustments?
No two homes are identical. You need to adjust each comp's sale price to account for differences. Common adjustments:
What should I know about presenting your comps?
Use a clean comparison table. The review board sees dozens of cases. Make yours easy to follow.
Let Our Engine Find Your Comps
Our Comparable Sales Engine searches multiple data sources, selects the strongest comps for your property, calculates adjustments, and formats everything into a presentation-ready evidence packet. All for a one-time $79 fee.