How to find comparable home sales in your neighborhood for a tax appeal

Last updated 2026-07-09

What are comparable sales and why do they matter for property taxes?

Comparable sales, almost always called comps, are recent sales of homes that resemble yours in the ways an appraiser or assessor actually cares about: location, size, age, style, condition, and features like a garage or finished basement. They matter because most states require assessors to value residential property at or near its market value, and market value is defined by what buyers actually paid for similar homes.

The connection to your tax bill is direct. If your assessor says your house is worth $450,000 but three houses almost identical to yours sold for $370,000 to $390,000 in the same period, you have a concrete, data-based argument that your assessment is too high. Boards of equalization and county hearing officers see dozens of appeals every day. Vague objections like "my house is old" or "the market is soft" rarely move them. A table of comps with addresses, sale dates, price per square foot, and a brief note on how each one compares to yours? That moves them.

The International Association of Assessing Officers (IAAO) publishes standards that most state assessment statutes track. Under those standards, the assessment-to-sale ratio for a jurisdiction should fall between 90% and 110% of market value ^[1]. If your assessment implies a ratio outside that band, you have a procedural argument on top of your comp evidence. That is a lever many DIY appellants overlook.

Where can I find comparable home sales in my neighborhood for free?

You have more free sources than you probably realize, and most of them beat anything you'd pay for.

Your county assessor's website. Start here. Almost every assessor in a mid-size or larger county now publishes a searchable property database. You can filter by street, subdivision, sale date, square footage range, and year built. The data comes from recorded deeds, so it is the same data the assessor used when they valued your house. Los Angeles ^[2], Cook County in Illinois ^[3], and Maricopa County in Arizona ^[4] all run detailed public search tools. Smaller counties sometimes only have a PDF report, but even that contains what you need.

State deed and transfer databases. Many states record transfer taxes at the county clerk or recorder level, and those filings are public. In some states, the Department of Revenue publishes statewide sales ratio studies with individual sale records. New York, for example, publishes an annual sales ratio study through the Office of Real Property Tax Services ^[5].

Redfin and Zillow. Both pull from MLS feeds and county records. Redfin's sold-listings search lets you filter by square footage, beds, baths, lot size, home type, and sale date. Zillow's "Recently sold" filter works similarly. Neither is a primary source, but they give you fast coverage and let you flag candidates before you verify the exact sale price in the county records.

The Federal Housing Finance Agency (FHFA) House Price Index. This won't give you individual transactions, but it gives you neighborhood-level price trends by quarter, which helps when you need to argue that values in your ZIP code have fallen since the assessment date ^[6].

PropStream, Realist, and similar paid tools. Skip these for a single appeal. The free county data gets you everything you need. If you own multiple parcels or are doing this commercially, that calculus changes, but for one house the free path is fine.

For counties with sophisticated online tools, start there and cross-check one or two sales on Zillow to confirm prices. For counties with minimal online data, go to the county recorder's office in person or request a print run of recent sales by subdivision. Most recorders provide this at no cost or for a nominal fee, typically under $10 ^[7].

What makes a sale truly comparable? The filters that actually matter

Not every nearby sale qualifies. Assessors and appeal boards apply specific criteria, and so should you when you build your comp set. Using a weak comp that the county easily dismisses undermines your whole presentation.

Arm's-length transaction. The sale must be between an unrelated buyer and seller, with no duress. Foreclosure sales, estate sales at deep discounts, sales between family members, and sales where the seller carried financing at a below-market rate are all suspect. Most assessors exclude them from their sales ratio studies for exactly this reason. Slip a foreclosure comp in without flagging it, and a sharp assessor will call it out. Then the rest of your data looks sloppy.

Recency. A useful rule of thumb: sales within 12 months before your assessment date are strong; sales between 12 and 24 months are usable with a time-adjustment; sales older than 24 months are very difficult to use unless you can document the market was stable. Many state statutes specify the look-back window explicitly. In Texas, for instance, the standard appraisal date is January 1, and the Tax Code instructs appraisers to use "comparable sales" without defining the window by statute, but Texas appraisal district guidelines generally favor the prior 12 months ^[8].

Physical similarity. The IAAO recommends keeping gross living area (GLA) within plus or minus 20% of your subject property ^[1]. A 1,400-square-foot house and a 2,400-square-foot house are not comparable without substantial adjustments, and an appeal board will not do that math for you. Same story with lot size: a half-acre lot in a neighborhood of quarter-acre lots needs an adjustment.

Location. Same neighborhood or subdivision is ideal. Cross a major road, a school district boundary, or a flood-plain line and you introduce variables that are hard to control. A mile radius is a reasonable starting rule. Tighter is better.

Condition and updates. A fully renovated kitchen and bath easily adds 5% to 10% of value. If your house has original 1978 fixtures and your comp was gut-renovated last year, note that difference or the comp works against you.

Filter criterion	Strong comp	Weak comp (use cautiously)	Disqualify
Sale date	Within 12 months of assessment date	12-24 months prior	Older than 24 months
Distance	Same subdivision or 0.5 mi	0.5-1.0 mi, same market	Different school district / flood zone
GLA difference	Within 10%	10-20%	Over 20% without adjustment
Transaction type	Open-market MLS sale	Estate sale with normal pricing	Foreclosure, REO, family transfer
Condition	Similar to subject	One update tier different	Substantially renovated vs. original

Aim for 3 comps that all point the same direction. Six is better. Three sales that each individually support a lower value than your assessment build a case that is hard to dismiss.

How do I pull comp data from my county assessor's website step by step?

The exact interface varies by county, but the process is the same nearly everywhere.

First, find the parcel search or property lookup tool on your county assessor's homepage. Search for your own parcel first. Note your property's recorded square footage, year built, lot size, and style (ranch, two-story, etc.). These are the filters you will use to find comps.

Second, find the "sales" or "recent sales" section. Many assessor sites have a dedicated sales search, separate from the property lookup. In Los Angeles County, the Assessor's portal lets you search by APN, address, or subdivision name and filter by sale date range ^[2]. In Cook County, the Assessor's office publishes a PIN search that shows sale history ^[3].

Third, set your filters. Use a half-mile to one-mile radius around your address, a sale date within the past 12 months (or extending to 24 months if the market was thin), and a square footage range of plus or minus 15%.

Fourth, export or screenshot the results. If the site offers a CSV download, take it. Otherwise, screenshot each result page. You need: address, sale date, sale price, square footage, year built, lot size, and style. That is your raw data.

Fifth, cross-check each candidate sale on Zillow or Google Street View. Look for anything that would disqualify it: obvious distress listing history, photos showing dramatically different condition, or a listing that came back to market very quickly (which can signal a non-arm's-length deal).

Finally, calculate price per square foot for each comp and for your assessed value. Price per square foot is the single most useful normalization metric for a residential comp grid because it controls for size differences fast. If your assessment implies $210 per square foot but your comps averaged $175 per square foot, you have a clean numerical argument.

How do I adjust comps when they aren't perfectly similar to my house?

No comp is perfect. The adjustment process is how professional appraisers handle this, and you do not need an appraiser's license to use the logic in an appeal.

The approach is called a sales comparison adjustment grid. You list each comp, then add or subtract dollar amounts (or percentages) for differences versus your home. A comp with a garage when your house has none gets a downward adjustment: you subtract the garage's estimated value from the comp sale price to get an adjusted price. A comp that is newer than your home gets an upward adjustment: you add something to bring it down to your house's quality level.

Where do adjustment amounts come from? The most defensible source is your own county assessor's cost schedule, often published in the assessor's annual report or available on request. Assessors typically assign dollar values to features like garages, pools, fireplaces, and finished basements. Using their own numbers makes it very hard for them to dispute your math.

If the county does not publish feature values, you can use published appraisal cost manuals like Marshall and Swift (now CoreLogic) or cite local remodeling cost surveys like Remodeling Magazine's Cost vs. Value report ^[9], acknowledging that these are national averages and actual local values may differ.

For most residential appeals, you actually do not need a formal adjustment grid. If your unadjusted comps all came in lower than your assessment, that raw data is often enough. Save the adjustment grid for situations where a comp is 15% larger or has a significant feature your home lacks. Keep the math simple and transparent. A board member following a half-page grid is persuaded. A board member staring at a six-page spreadsheet gets annoyed.

One more thing: if your comps need large adjustments in multiple directions, they probably are not strong comps. Find better ones. The goal is not to prove you can math your way to a lower number. It is to show that homes genuinely like yours sold for less.

How many comps do I need to win a property tax appeal?

Three is the floor. Most assessor appeal boards expect at least three comparable sales, and some state rules explicitly require a minimum. In Georgia, for example, the Board of Equalization process works best with at least three comps presented in writing before the hearing ^[10].

Six is the sweet spot for a strong case. With six comps, you can afford to have one or two that the assessor challenges on condition or distance grounds, and you still have four pointing toward a lower value. That redundancy matters.

More than ten comps rarely helps and can hurt by making your presentation feel padded. If you have 12 sales and only 4 actually support your position while 8 are neutral or unfavorable, presenting all 12 hands the assessor ammunition.

One strong, well-documented comp is sometimes enough if the property is highly distinctive and similar sales are genuinely rare. A rural property, a historic home, or an unusual floor plan may have only two or three real comps in any given year. In those cases, document why the pool is thin and be transparent about it.

Quality beats quantity, every time. Three comps that are geographically tight, recent, arm's-length, and physically similar to your house will outperform nine loosely chosen comps in almost every appeal.

What time period should comp sales cover for a property tax appeal?

This depends on your state's assessment date and statute, but the general rule holds: sales that closed within 12 months before your assessment date are your primary evidence. Sales between 12 and 24 months prior are secondary and generally require a time-trend adjustment. Sales after the assessment date can sometimes be used, with caveats.

Most states set a specific lien date or valuation date. California's is January 1 ^[11]. Texas's is January 1. New York's varies by municipality but is often July 1 for cities or March 1 for many towns. Check your notice of assessment for the exact date; it is usually printed on the form.

Using post-assessment-date sales is allowed in some jurisdictions if prices have fallen since the assessment date and you want to show a downward trend. The reasoning is that a sale six months after January 1 reflects what buyers were willing to pay in a market continuous with the assessment date. Not all boards accept this argument, but it is worth knowing if recent sales support your case and the older sales do not.

For markets with very low transaction volume (rural areas, high-end enclaves), some states allow extending the window to 36 months with documented time adjustments. The IAAO standard is to use the 12-month period centered on the appraisal date when possible, and to extend only when necessary for statistical reliability ^[1].

Can I use Zillow or Redfin comp data in an official appeal?

Yes, with one caveat that can sink you if you skip it: always verify the sale price against the county's recorded deed or assessor database before you put a number in your appeal packet.

Zillow and Redfin are useful for finding candidates fast, but they are not primary sources. Prices on those platforms occasionally lag recorded deeds by a few weeks, or reflect the list price rather than the final sale price. A $382,000 Zillow listing might have closed at $368,000 after concessions. If you cite $382,000 and the assessor pulls the deed and finds $368,000, your credibility takes a hit.

The verification step takes about two minutes per comp. Go to your county recorder's or assessor's website, search the address, find the deed or transfer record, and confirm the exact sale price and date. Screenshot that page and include it in your appeal evidence.

Once you have verified prices, citing Redfin or Zillow listings (with screenshots of the property photos, square footage, and description) is fine as supporting documentation. The photos help establish condition. The listing description confirms features like garage count, pool, and finished basement. Boards find that context helpful.

For larger metro areas like Los Angeles County, San Diego, Cook County, or Maricopa County, the assessor's portal is usually detailed enough that you may not need Zillow at all. For smaller rural counties, the combination of Redfin or Zillow to find candidates plus county deed records to verify is the most practical workflow.

How do I organize my comp evidence for the actual appeal hearing?

Presentation matters almost as much as the data. A board member who has seen 30 appeals today gives more weight to a clean, easy-to-read packet than to an identical set of facts buried in a confusing printout.

The one-page comp grid is the centerpiece. Set it up as a table with one row per comp: address, sale date, sale price, GLA in square feet, lot size, year built, and price per square foot. Add a final row for your own property at the assessed value. The comparison is immediately visual.

Behind that grid, include one page per comp with: a screenshot from the county assessor's database showing the confirmed sale price and property details, a Redfin or Zillow listing screenshot with the property photo, and any notes on adjustments (if the comp has a pool and your house does not, note that briefly).

If you have a price-per-square-foot argument, add one sentence or a simple bar chart showing the average comp price per square foot versus the implied price per square foot at your current assessment.

Keep the whole packet under 15 pages. Front it with a one-paragraph cover memo stating your parcel number, your current assessed value, your requested reduction, and the basis (comparable sales). Sign and date it.

For counties like Bexar County, Gwinnett County, or Cherokee County in Georgia, you typically submit this packet before the hearing date, sometimes as early as 5 business days in advance. Check your specific county's rules because late submission can get the evidence excluded.

TaxFightBack's DIY appeal kit includes a pre-built comp grid template and a cover memo you can fill in with your numbers, so you do not have to start from a blank spreadsheet.

One last tip: bring three copies to the hearing. One for yourself, one for the board, and one for the assessor's representative. Assessor reps sometimes show up without your packet even if you submitted it correctly.

What if the assessor has different comps that support a higher value?

This happens. The assessor may present their own comp grid at the hearing, and their comps may show higher prices per square foot than yours. Here is how to handle it.

First, look at each of their comps for disqualifying features. Are any of them foreclosure sales on the high end (which would be unusual but possible in a rapidly rising market)? Do any have significantly more square footage or major amenities your house lacks? Were they in a slightly different neighborhood or subdivision with higher values? Note these differences specifically and out loud at the hearing.

Second, look at the dates. If their comps are older than yours, the market may have softened in the intervening period. Citing a local price index trend from FHFA data ^[6] to show the direction of the market strengthens this argument.

Third, accept that the board may weight the assessor's comps. Some boards default to the assessor unless you present clear, disqualifying reasons to ignore their data. Your goal is not always to win to your requested number. Even a partial reduction is money back in your pocket.

Fourth, focus on the outliers. If the assessor presents six comps and two of them are genuinely strong while four are weaker, point to the four and explain why they should carry less weight. You do not have to attack all six.

Finally, stay calm and specific. Saying "your comp at 123 Elm sold with a pool my house doesn't have, and the county's own cost schedule values pools at $20,000 to $30,000" is far more effective than "that comp is unfair."

Are comp sales the only evidence I can use, or should I combine them with other arguments?

Comp sales are the strongest single piece of evidence in most residential appeals. But stacking a second type of evidence makes your case more resilient.

The most common complement is the income approach, but that applies to rental properties, not owner-occupied homes. For a single-family house, the other useful evidence types are:

A recent independent appraisal. A licensed residential appraiser's report carries significant weight because it is a signed, certified professional opinion that an appeal board cannot easily dismiss. The cost is real, typically $400 to $700 for a standard single-family appraisal in most markets (costs run higher in expensive coastal markets, sometimes over $1,000) ^[12]. Whether that cost is worth it depends on how large your potential savings are. If your assessment is $600,000 and you think it should be $480,000, a $500 appraisal to secure $1,500 or more in annual tax savings is a good investment. If your potential savings are $300 a year, it is not.

Condition evidence. Photos documenting deferred maintenance, structural issues, or outdated systems can explain why your property should trade at the low end of the comp range even when the comps themselves look similar. This evidence does not stand alone, but it explains adjustments you are making to comp prices.

Mass appraisal errors. If the assessor's records show the wrong square footage, wrong number of bathrooms, or attributes of a non-existent room, that is a factual correction argument, not a comp argument. It is often the fastest and cleanest path to a reduction because there is nothing to debate: the record is wrong.

For counties with detailed data systems, like Bibb County or Madison County, verify your property card details before you ever pull a single comp. A data error fix takes one sentence at a hearing. A comp case takes a packet and preparation.

What common mistakes kill a comp-based appeal?

A few patterns come up over and over.

Using foreclosure or REO sales as your comps. Boards almost always discount these. If a house sold at a 30% haircut because of distress, it does not represent what a willing buyer would pay under normal conditions. Use it as a floor data point in your narrative if you want, but do not anchor your comp grid to it.

Ignoring the assessment date. Using sales from after a market peak to argue a pre-peak assessment is too high is backward. Make sure you know the valuation date and that your comps are from the right window.

Cherry-picking without knowing it. If you pull five comps and they all support your case, great. But if the assessor pulls ten comps from the same period and seven of them support a higher value, you have a selection problem. Always search the full universe first, then understand why your picks are stronger rather than simply that they point the way you want.

No photos or condition documentation. A bare price grid without any visual context for condition differences gives the assessor room to argue you are comparing apples to oranges. Include photos.

Missing the deadline. This is not a comp issue per se, but the most airtight comp evidence in the world does nothing if you file after the appeal window closes. Deadlines vary widely: 30 days from notice receipt in some states, up to 90 days in others. Check your county's specific rules. Lake County property tax deadlines in Illinois, for instance, differ from those in St. Louis County in Missouri. Never assume.

Rounding sale prices. Present exact prices as recorded, not rounded figures. $371,500, not "about $370k." Precision signals that you verified the data.

Frequently asked questions

How far away can a comparable sale be and still count?

As a practical rule, sales within half a mile and in the same subdivision are strongest. Sales between half a mile and one mile are usable if the neighborhood characteristics are similar. Once you cross major roads, school district lines, or zoning boundaries, the comp becomes harder to defend. If your market is low-volume and you have no choice, document why you had to go farther.

Can I use a comp sale that happened after my assessment date?

In many jurisdictions, yes, as supplemental evidence showing market direction. Some state boards accept post-assessment-date sales to show that values declined after the valuation date. However, most states primarily weight sales before or concurrent with the assessment date. Check your state's assessment statutes or the rules posted on your county assessor's website to confirm whether post-date sales are admissible in your jurisdiction.

Do I need a licensed appraiser to find and use comps?

No. Any property owner can research and present comp sales in an administrative appeal. A licensed appraisal report carries more weight and is harder for the assessor to dismiss, but it is not required. For appeals where the potential annual savings exceed $1,000 to $1,500, an appraisal is worth considering. For smaller assessments, DIY comp research is a fully legitimate and widely accepted approach.

What is a sales ratio study and should I use one in my appeal?

A sales ratio study compares assessed values to actual sale prices across a jurisdiction to measure assessment accuracy. Your state's department of revenue or property tax division often publishes these annually. If the study shows your county's assessments average 115% of sale prices, that is evidence the entire roll is over-assessed, which supports your appeal. It is a strong macro argument to pair with your individual comp evidence.

How do I find sold prices if my county doesn't publish them online?

Go to the county recorder's or register of deeds office in person or by mail and request recent sales records for your neighborhood. Many states treat deed transfer information as public record and provide it at low or no cost. Some states have transfer tax stamps on the deed itself that indicate the sale price. Alternatively, a local real estate agent may pull an MLS report for you as a goodwill gesture, though you should verify prices against recorded deeds.

Can my neighbor's lower assessment serve as a comparable?

An assessed value comparison is a separate argument from a comp sale argument. You can argue that your house is assessed higher than a nearly identical neighboring property, which is an equity argument under most state assessment equity statutes. This is a valid appeal path but distinct from using actual sales. The strongest appeals often combine both: equity with a neighbor plus comp sales showing market value is lower than your assessment.

What does price per square foot tell me and how do I calculate it?

Price per square foot is the sale price divided by the gross living area in square feet. It normalizes for size differences across comps. If four nearby sales averaged $175 per square foot and your assessment implies $210 per square foot, you have a direct, clean argument for a 17% reduction. Always use the same square footage definition (typically heated living area, excluding garage and unfinished basement) across all comparisons.

Should I include comps that are slightly unfavorable to my argument?

You do not have to present every sale you found, but deliberately hiding strong contrary evidence is risky. The assessor may have it and present it, making you look like you cherry-picked. A better approach: include a comp that is slightly above your argument and explain why it differs (better condition, larger lot, renovated kitchen). Showing you considered the full picture and can explain the outliers actually strengthens your credibility with the board.

How many years back can comp sales go for a property tax appeal?

Most jurisdictions favor sales within the 12 months before the assessment date. Many allow extending to 24 months when recent sales are scarce. A handful of states permit up to 36 months with documented time adjustments. The IAAO standard recommends the 12-month window centered on the appraisal date when data is sufficient. Check your specific state statute, because some set the look-back period explicitly by law.

What if all the recent sales near me are higher than my assessed value?

Then your assessment may actually be accurate or even favorable, and you should think carefully before appealing. An appeal that produces evidence of a higher market value can sometimes result in an increased assessment in jurisdictions that allow upward adjustments after a hearing. Review your state's rules on this before filing. If all comps support or exceed your assessed value, your energy is better spent on exemptions or a property record correction rather than a comp-based appeal.

Can I use a comp sale from a new construction subdivision near my older home?

Rarely. New construction typically sells at a premium over resale homes because of builder warranties, modern systems, and design features. Using a new construction sale as a comp for an older house almost always works against you, since the new build price is higher. The exception is if you can argue the new construction comp, after adjusting for age and condition, still supports a lower value than your assessment, but that argument requires careful documentation.

What is the difference between a comparable sale and a listing price?

A listing price is what a seller asks. A sale price is what a buyer paid. For property tax purposes, only closed, recorded sale prices count as evidence. Listing prices are irrelevant and, if presented as comp evidence, will be dismissed immediately by any experienced assessor or board member. Always verify that a property actually sold and use the recorded sale price from the deed, not the asking price from a listing website.

Do I need to submit comps before the hearing or can I bring them the day of?

This varies by county and state. Many jurisdictions require you to submit your evidence packet a set number of days before your scheduled hearing, sometimes 5 business days, sometimes 10. Some allow same-day presentation. Check your appeal notice or county assessor's procedural rules carefully. Showing up with undisclosed evidence at the hearing itself risks having it excluded entirely, which would leave you presenting nothing.

Sources

1. International Association of Assessing Officers (IAAO), Standard on Ratio Studies: IAAO standard that assessment-to-sale ratios should fall between 90% and 110% of market value for a jurisdiction, and that the 12-month window centered on the appraisal date is preferred for comp selection.
2. Los Angeles County Office of the Assessor, Property Search: The Los Angeles County Assessor provides a public property and sales search tool searchable by APN, address, or subdivision with a sale date range filter.
3. Cook County Assessor's Office, Property Search: Cook County Assessor publishes a PIN search tool showing sale history for individual parcels.
4. Maricopa County Assessor, Parcel Search: Maricopa County Assessor provides a public property search tool with sale records.
5. New York State Department of Taxation and Finance, Office of Real Property Tax Services: New York publishes an annual sales ratio study with individual sale records through the Office of Real Property Tax Services.
6. Federal Housing Finance Agency, House Price Index: FHFA publishes a House Price Index with neighborhood-level price trends by quarter, useful for documenting market direction around an assessment date.
7. National Association of Counties, County Services Overview: County recorder offices typically provide recent sales records at no or nominal cost, often under $10.
8. Texas Comptroller of Public Accounts, Property Tax Appraisal: Texas Tax Code sets January 1 as the standard appraisal date and Texas appraisal districts generally favor the prior 12 months for comparable sales.
9. Remodeling Magazine / JLC Media, Cost vs. Value Report: Remodeling Magazine's Cost vs. Value report publishes national and regional average costs and resale values for common home improvement projects, usable as a reference for comp adjustments.
10. Georgia Department of Revenue, Property Tax Division: Georgia Board of Equalization process works best with at least three comp sales presented in writing before the hearing.
11. California State Board of Equalization, Property Tax Rules: California's property tax lien and valuation date is January 1 each year.
12. Appraisal Institute, Residential Appraisal Cost Overview: A licensed residential appraisal typically costs $400 to $700 in most markets, with higher costs in expensive coastal markets sometimes exceeding $1,000.