Ask any assessor what actually moves them at a hearing and you'll hear some version of the same answer: show me what similar homes actually sold for. Opinions don't win appeals. Zestimates don't win appeals. Three recent sales of homes like yours, laid out clearly, win appeals. This guide teaches you to find them, check them, adjust them, and present them.
What makes a good comp
Before you open a single website, know what you're hunting. A strong comparable sale has six traits:
- Sold, not listed. A listing price is a wish. A sale price is a fact. Until a sale closes, you don't know what the home was actually worth — this is the single most important filter, and the one beginners skip most.
- Recent. Aim for sales within the last 6–12 months. Older sales get stale fast in moving markets, and many boards discount them.
- Nearby. Start within a half-mile to a mile — same subdivision or school zone if possible. Expand only if you must, and explain why.
- Similar size. Within about 20% of your square footage, and a similar bedroom/bath count. A 1,200-square-foot ranch doesn't comp a 2,400-square-foot two-story.
- Similar age, style, and condition. Same property type (single-family to single-family — never condos to houses), roughly the same era, and honestly assessed condition. This is where your photos of your own home's condition earn their keep.
- Arm's-length. A normal sale between a willing buyer and seller. Foreclosures, short sales, family transfers, and investor flips at distressed prices are weak comps — and some boards disregard them entirely.
Three to five comps that hit most of these traits will beat a spreadsheet of twelve that don't. Quality is the whole game.
The walkthrough: finding your comps
Step 1 — Know the number you're beating
Write down your assessed value and your county's assessment ratio before you look at a single sale. This matters because in many states, assessed value is not market value — it's a fraction of it. Georgia assesses residential property at 40% of fair market value statewide. Cook County, Illinois assesses residential (Class 2) property at 10% of market value. So a $400,000 sale in Georgia implies a $160,000 assessment, while the same sale in Cook County implies $40,000. If you compare raw sale prices to your assessed value without the ratio, your math will be nonsense. (More on this in the assessment-ratio section below.)
Step 2 — Pull sold homes on Zillow
Zillow is the fastest starting point because its sold-data search is free and doesn't require an account:
Filter for "Recently Sold"
- Search your address, then switch the listing filter from "For Sale" to Sold (often labeled "Recently Sold").
- Set the sold-date range to the last 12 months — tighter if your market has plenty of sales.
- Zoom the map to roughly a one-mile radius around your home. In dense suburbs, try a half-mile first.
- Use the beds/baths/sqft filters to bracket your home: if you're at 1,800 sqft, filter roughly 1,450–2,150.
- Open each promising sale and read the listing: sale date, sale price, square footage, lot, year built, and — critically — the photos. A comp with a renovated kitchen is not your comp if yours is original.
- Ignore the Zestimate on every page. You're here for the sale facts, not the algorithm's opinion.
Zillow's own guide to finding real estate comps makes the same core points: only sold homes count, match the property type, study the photos, and read the listing description for upgrades you can't see in pictures (a new roof, for example, can explain a price gap).
Step 3 — Cross-check on Redfin
Redfin's sold data sometimes catches sales Zillow misses, and its filters are excellent. Repeat the same exercise: sold filter, 12-month window, tight radius, size bracket. Where the two sites disagree on a sale price or date, the county record wins — which brings us to the step most DIY guides skip.
Step 4 — Verify against county records
Websites have errors: wrong sale dates, missing sales, mislabeled square footage. Your county assessor's or recorder's website has the official record — parcel data, recorded sale prices, and dates. Look up each of your candidate comps and confirm the sale price and date match what Zillow and Redfin showed. If they don't, use the county's numbers. Boards trust county records; showing that your comps are verified against them makes your packet materially stronger.
Texas owners: the non-disclosure wrinkle
Texas is a non-disclosure state — sale prices aren't public record the way they are elsewhere, so county sites won't hand you your neighbors' closing prices. You still have options: your appraisal district must share the evidence it plans to use at your hearing (request it in writing), a local realtor can pull MLS comps for you, and your own purchase price — if you bought within the last year or two — is itself a strong comp. Our Texas guide covers this in detail.
Step 5 — Do the assessment-ratio math
This is the step that separates winning packets from confusing ones. Your assessed value and your comps' sale prices live in different units until you convert them.
The basic math: assessment ratio = assessed value ÷ market value. If your home is assessed at $300,000 and truly worth $300,000, your ratio is 100%. If your county assesses at a fraction of market value, convert your comps into the same terms: a $400,000 sale in a 40%-ratio state implies a $160,000 assessment.
The equalization wrinkle: some states layer an equalization ratio on top. New Jersey is the classic example: each municipality has a state-certified average ratio, and appeals are judged against a "common level range" of that ratio plus or minus 15%. If your town's ratio is 85% and your assessment divided by your proven market value lands inside the 72.25%–97.75% range, the board considers the assessment fair even if the raw numbers look high. Check whether your state or county publishes an equalization or "common level" ratio — if it does, your math has to run through it.
Practical rule: never put a raw sale price next to your assessed value in your packet without showing the conversion. One line — "Sale price $400,000 × 40% county ratio = $160,000 indicated assessment vs. my $185,000 assessment" — is worth more than a page of unconverted numbers.
Step 6 — Adjust your comps honestly
No comp is identical to your home, and boards know it. What they respect is honest adjusting: start from the comp's sale price and adjust up or down for meaningful differences.
Adjust for what a buyer would actually pay for
- Size: the most common adjustment. If the comp is 200 sqft larger and local price-per-square-foot is ~$150, subtract ~$30,000 from the comp's price to compare it to your home. Derive the per-square-foot figure from your comp set itself, not from a website.
- Condition and updates: a renovated kitchen and baths vs. your originals is worth a real adjustment — use contractor estimates or the price gaps between updated and original sales in your area, not guesses.
- Lot and location: busy road vs. quiet cul-de-sac, significantly larger or smaller lot, backing to commercial — adjust where the market clearly prices the difference.
- Age and style: smaller adjustments, but note them so the board sees you're being careful.
The discipline that matters: adjust in both directions. If every adjustment favors you, the board will discount the whole exercise. A packet that adjusts one comp up (because it's inferior to your home) reads as honest — and honest packets win.
Step 7 — Build the comp grid
Your final product is a one-page grid the board can read in two minutes. Columns: address, sale date, sale price, square footage, $/sqft, key differences, adjustments, and indicated value for your home. Then a bottom line: the average or median indicated value, converted through your assessment ratio, versus your current assessment.
| Your home | Comp 1 | Comp 2 | Comp 3 | |
|---|---|---|---|---|
| Address | 123 Main St | 127 Main St | 45 Oak Ave | 130 Main St |
| Sale date | — | Mar 2026 | Jan 2026 | Nov 2025 |
| Sale price | — | $385,000 | $372,000 | $390,000 |
| Sqft | 1,800 | 1,950 | 1,800 | 1,700 |
| Key difference | — | +150 sqft, updated kitchen | Busy road | Smaller, original baths |
| Adjustments | — | −$37,500 | +$8,000 | +$12,000 |
| Indicated value | $359,000 avg | $347,500 | $380,000 | $402,000 → $378,000* |
* Simplified illustration — your grid shows the full adjustment math per comp, converted through your county's assessment ratio. (The Playbook includes a fill-in comp grid worksheet.)
What NOT to use as comps
- Active listings. Asking prices are aspirations. Some boards will glance at them as supporting context; none will treat them as evidence of value.
- Foreclosures and short sales as your primary comps. Distressed sales sell below market by definition, and many boards disregard them. One in a supporting role is fine; a case built on them looks cherry-picked.
- Your Zestimate or Redfin Estimate. Useful for your own orientation, useless as evidence. If you cite an algorithm's estimate at a hearing, you've told the board you didn't do the work.
- Comps from a different market. The sale across the highway in the better school zone isn't comparable, and the board knows the area better than you do. Don't insult their local knowledge.
Putting it together
The full sequence, on one evening: pull your assessed value and county ratio → filter sold homes on Zillow within a mile and 12 months → cross-check on Redfin → verify prices and dates against county records → convert through your assessment ratio → adjust honestly → lay it out in a one-page grid. That's the backbone of your evidence packet, and it's the same work a $49 packet service or a contingency firm would do — you're just doing it yourself, which means you understand your own case better than anyone you could hire.
Comps usually pair with the other two legs of a winning appeal — errors in your property record and condition documentation. Our complete appeal guide shows how the three fit together, and the letter template shows you how to write the whole thing up.
Frequently asked questions
How many comparable sales do I need for a property tax appeal?
Three to five strong comparables beat ten weak ones. Pick the sales most similar to your home in location, size, age, and condition, sold as recently as possible. A tight set of three well-adjusted comps is more persuasive than a long list of marginal ones.
Can I use my Zillow Zestimate as evidence in a tax appeal?
No — not as evidence. Automated estimates are useful starting points for your own research, but appeal boards want actual arm's-length sales of comparable homes, verified against county records. Use Zillow and Redfin to find sold homes, then build your case from the sales themselves.
What is the assessment ratio and why does it matter?
The assessment ratio is assessed value divided by market value. Many states assess at a fraction of market value — Georgia at 40%, Cook County residential at 10% — so you must convert your comps into assessment terms before comparing. Some states add an equalization ratio on top (New Jersey's "common level range" is the classic example). Never put a raw sale price next to your assessed value without showing the conversion.
Do comparable sales have to be in my neighborhood?
As close as possible — start within a half-mile to a mile, in the same subdivision or school zone. If your area has few recent sales, expand gradually, but the farther a comp is, the more you need to justify it, and the weaker it becomes.
Keep going
Comps are half the battle. The Playbook covers the rest.
Fill-in comp grids, adjustment worksheets, the property-record audit, and hearing scripts — the $29 DIY system.
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