Does a realtor CMA work as evidence in a property tax appeal?

Last updated 2026-07-09

What is a CMA and how is it different from an appraisal?

A CMA is a document a real estate agent prepares, usually for free, to help a seller price a home or a buyer decide on an offer. It lists recent sales of comparable properties, makes rough adjustments for size, condition, and features, and lands on a suggested value range. The whole thing might take an agent an hour with MLS access.

A certified appraisal is a different animal. A licensed or certified appraiser follows the Uniform Standards of Professional Appraisal Practice (USPAP), signs the report under oath, and takes on professional liability for the conclusion. USPAP is published by the Appraisal Foundation under authorization from the Financial Institutions Reform, Recovery, and Enforcement Act of 1989 (FIRREA). ^[1] The appraiser physically inspects the property, documents it with photos, and supports every adjustment with market data.

A CMA carries none of that. The agent does not inspect your home formally, does not follow USPAP, and faces no professional consequence if the number is wrong. That gap matters the moment you walk into a hearing.

Will a board of equalization or ARB actually accept a CMA as evidence?

Sometimes, depending on state law and the board's own rules. Never as the strongest thing you can bring. Most boards will look at a CMA, note the comps, and then discount it the second the assessor's rep points out it is not a certified appraisal.

Most state appeal statutes describe acceptable evidence in general terms. Texas Property Tax Code Section 41.43 says the appraisal district has the burden of establishing value "by a preponderance of the evidence" once a taxpayer presents "evidence that the appraisal district's value is unequal or excessive." ^[2] The code never demands a certified appraisal. That leaves room for a CMA, but only if it genuinely backs your position.

Here is what hearing officers tend to do with one. They look at it. They probably note the comparable sales it lists. But if the assessor's representative objects that it is not a certified appraisal, the board gives it less weight, or makes you walk through every comp yourself and explain why each one is truly comparable. A CMA handed over without a word rarely moves anything.

New York City's Tax Commission, which handles residential and commercial appeals, requires appraisals to be prepared by a New York State licensed or certified appraiser to receive full evidentiary weight. ^[3] A broker's CMA would not clear that bar for a formal filing, though it might help an informal review.

Cook County, Illinois runs the same play. The Cook County Assessor and the Board of Review both accept market evidence broadly, but appraisals carry far more weight in contested hearings. ^[4] If you are appealing there, our guide on the cook county tax assessor tax bill covers the full process.

When does a CMA actually help your appeal?

There are real situations where a CMA earns its place, even when it is not the star of the show.

Start with early informal reviews. Many counties offer an informal hearing before any formal board proceeding. An assessor's staffer looks at your file and decides whether to adjust. At this stage, a CMA showing three or four tight comps that sold below the assessed value can absolutely move an informal reviewer. You are not in a formal evidentiary proceeding. You are having a conversation. Bring the CMA, point at the comps, make your case.

Second, a CMA can anchor your own comp grid. The best DIY appeal evidence is a plain spreadsheet: your subject property on one row, five to ten comparable sales below it, adjusted for square footage, year built, lot size, and condition. A CMA gives you a starting list. You verify each sale against the public record yourself. The public record is what the board trusts.

Third, a CMA from a local agent who will appear at the hearing or sign a written statement explaining the comp selection beats a bare printout. The agent's market knowledge becomes testimony instead of paper.

Fourth, if the CMA value comes in dramatically below the assessed value, say 20 percent or more, it signals to the board that something is worth a look. Boards are not robots. A credible document showing a big gap prompts questions.

What makes comps strong or weak in a property tax appeal?

Whether the comps come from a CMA or your own digging, the board runs the same tests.

Proximity. Sales within a mile of your home beat sales two miles out. In rural areas you sometimes have to reach farther, but then you need to explain why.

Recency. Most boards want sales within twelve months of the assessment date. Texas ARBs focus on sales close to January 1 of the tax year. ^[2] If the market swung hard, older sales can cut against you.

True comparability. A 1,400-square-foot ranch and a 2,200-square-foot colonial are not twins. Age, condition, lot size, garage, basement, and school district all count. If a CMA leans on a sale that needed a big adjustment and the agent never explains the adjustment, the board discounts it.

Arms-length transactions. Foreclosures, estate sales, and deals between related parties are not arms-length. Slip one into your comp set and you get challenged fast. The assessor almost certainly knows which neighborhood sales were distressed.

A CMA printed from an MLS system often carries no adjustment detail at all. The agent picks comps, maybe tweaks a few dollars per square foot, and hands you a range. Fine for pricing a listing. Thin for a hearing.

The strongest comp packages for DIY appeals use public deed records and the county's own property card data to build adjustments. Montgomery County, Maryland publishes assessment data and comparable sales online, so homeowners can build a grid entirely from official sources. ^[5] Our breakdown of montgomery county property tax covers that jurisdiction.

How much does a certified appraisal cost, and is it worth it for a tax appeal?

A residential appraisal from a certified appraiser runs roughly $300 to $500 for a typical single-family home in most U.S. markets. Complex properties or high-cost metros can push it past $700. ^[6] The Appraisal Institute does not publish a national average, but that range matches what major lenders and homebuyers report paying.

Whether it is worth it comes down to the dollars at stake. Say your assessed value is $400,000 and you think it should be $340,000. A $400 appraisal that wins a $60,000 reduction is an easy yes. At a typical effective property tax rate of 1.1 percent (the rough U.S. median per the Lincoln Institute of Land Policy), that reduction saves about $660 a year, every year, until the next reassessment. ^[7]

Now say your assessed value is $180,000 and you think it should be $168,000. The math flips. A $400 appraisal chasing $132 a year might not pencil out in year one, though it can pay off over several years.

For small-dollar appeals, a well-built comp grid from public sales data gets you most of the way there for free. That is the heart of the DIY approach. Our appeal kit at TaxFightBack walks through building that grid step by step if you want a set format.

For larger commercial properties, an appraisal is almost never optional. Boards expect it, and the savings justify it many times over. Hennepin County, Minnesota spells out commercial evidence standards in its appeals process. ^[8] See our guide on hennepin county property tax.

Does the state matter? How evidence rules vary by jurisdiction

The state matters enormously. Evidence standards are set by state statute, then interpreted by each board or court, and they differ enough to change your whole strategy.

State	Key evidence rule	Appraisal required?	CMA position
Texas	Taxpayer presents evidence; district bears burden after	No, but USPAP appraisal carries most weight	Accepted, low evidentiary weight
California	Taxpayer must show clear error or changed conditions	No formal requirement for informal review	Accepted at county assessor informal review
New York (NYC)	Tax Commission requires licensed/certified appraiser for full weight	Effectively yes for formal filing	Insufficient for formal TC appeal
Illinois (Cook Co.)	Board of Review accepts market evidence broadly	Not mandatory but strongly preferred	Accepted, often not decisive
Georgia	Board of Equalization uses preponderance standard	No, but appraisal strengthens case	Accepted; USPAP appraisal stronger
Florida	Value Adjustment Board follows Florida Statute 194	No, but appraiser report is standard for contested hearings	Accepted for informal reviews

Florida Statute 194.034 says "the petitioner may present testimony and other evidence relevant to the assessed value" without prescribing a specific form. ^[9] That opens the door to a CMA but gives it no special standing.

Georgia's appeal statute (O.C.G.A. Section 48-5-311) likewise lets taxpayers present evidence before a county Board of Equalization without mandating an appraisal. ^[10] The Gwinnett County Board of Assessors will consider market sales evidence from any credible source. See our Gwinnett guide: gwinnett county tax assessor.

The move here is simple. Read your state's appeal statute before deciding how much to spend on formal evidence. A few minutes of reading can save you hundreds on an appraisal you may not need.

Can your real estate agent appear at the hearing to support the CMA?

They can, and it helps. An agent who shows up, explains how they picked the comps, and answers the board's questions is giving testimony instead of dropping off a document. Testimony carries more weight than exhibits alone.

Before you ask, run through a few things. Does the agent know the neighborhood cold? Someone who mostly works across town but pulled your comps remotely will not hold up under the assessor's questions. Is the agent ready to defend the adjustments? If the board asks why they added $8,000 for the extra bathroom in comp three, the agent needs a real answer.

Some agents are genuinely good at this, especially those who list heavily in your neighborhood and understand assessment methodology. Others will happily print a CMA but have zero interest in sitting through a two-hour board session. Ask directly before you count on them.

If the agent cannot appear, a signed letter on their letterhead explaining the comp selection and their opinion of value beats nothing. It is still not an appraisal. It does show the board that a licensed professional looked at the situation.

What evidence beats a CMA in a property tax appeal?

Here is the rough order of impact.

1. A USPAP-compliant appraisal from a certified appraiser, done as of the assessment date. This is the gold standard because it mirrors what the assessor claims to have done.

2. Your own sales comparison grid built from recorded deed data, with adjustments documented from the county's own property records. Boards trust their own data. When you show up with their numbers, it is hard to wave away.

3. The assessor's own comparable sales, when they are bad ones. If the assessor used a sale that was not arms-length, or a property that differs sharply from yours, calling that out on the record is powerful.

4. A written repair estimate or contractor bid for documented deferred maintenance or defects. If your roof needs replacing and costs $18,000, that is real evidence of diminished value a CMA never captures.

5. Listing history showing the property sat on the market and could not sell at or near the assessed value. A stale listing is public proof that buyers, more than an agent, disagreed with the number.

6. The CMA, as supporting context for any of the above.

A CMA is not worthless. It is just rarely enough on its own.

How do you build a better comp grid than a typical CMA?

Start with the county's own sales data. Most county assessor websites publish recent sales records. Pull every arms-length sale within one mile of your property from the twelve months before the assessment date. Filter to properties with roughly similar square footage (within 15 to 20 percent), similar age, and the same basic configuration (single-family, same number of stories).

For each comp, record the sale price, the sale date, and the square footage. Divide sale price by square footage to get price per square foot. Average that figure across your best five to eight comps. Apply the average to your property's square footage. Compare that implied value to your assessed value.

When comps need adjustments for big differences, document them conservatively. Boards get suspicious of $50,000 adjustments that conveniently land you exactly where you want to be. Small, well-explained adjustments read as credible.

This grid, printed clean and attached to your appeal form, tells a clear story using data the assessor cannot dismiss as biased. It is close to what many assessors' offices would do themselves if you asked them to reconsider.

Texas homeowners can run the same play in Bexar County, where the Appraisal District publishes the comparable sales it used in your assessment. You can see them on your notice and challenge them head-on. More on the process: bexar county tax assessor.

California homeowners get the same treatment. The Los Angeles County Assessor publishes property characteristics and sales data so you can do the identical work. See our LA county guides: la-county-property-tax and los-angeles-county-property-tax.

Are there cases where a CMA actually hurts your appeal?

Yes. Three ways a CMA can turn against you.

First, if the CMA shows a value at or above the assessed value, you have just handed the assessor's rep a document backing their number. This happens when an agent runs a CMA for a different reason (say, you were thinking about selling) and the value lands high. Never submit evidence you have not read closely.

Second, if the comps are sloppy: different neighborhoods, very different sizes, recent sales that were not arms-length. The assessor's rep probably knows those sales. They will pick apart the problems, and now your own evidence is undercutting you.

Third, in some states a CMA can set a value floor that becomes part of the record. Argue your property is worth $290,000 because the CMA says so, lose the appeal, and that $290,000 figure may sit in the hearing record. This is a minority concern and most boards do not treat it this way, but it is worth knowing.

The clean approach: use the CMA to find good comps, verify them in the public record, and submit the public record data as your evidence. You keep the agent's comp-selection skill without the downside of a document that invites attack.

What does the appeal timeline look like and where does evidence preparation fit?

Most states tie the appeal deadline to the mailing date of the assessment notice, usually 30 to 90 days after it lands. Miss the deadline and you wait until next year, no matter how strong your evidence is.

After you file a protest or appeal, the sequence usually runs: informal review first (assessor's staff), then a formal hearing before the board if that does not resolve it, then a further appeal to a state-level court or administrative tribunal if the board rules against you.

Evidence preparation lives in the gap between filing and your hearing date. In Texas, ARB hearings are typically scheduled within 55 days of the protest filing deadline under Texas Property Tax Code Section 41.45. ^[2] Many happen from late May through July for the January 1 assessment date.

Gather your comps and build your grid before you file if you can. Strong evidence in hand lets you decide whether the appeal is even worth pursuing. If the comps show your assessment is actually fair, you just saved yourself weeks of hassle.

If you order a formal appraisal, give the appraiser at least two to three weeks of lead time. Some appraisers who specialize in tax appeal work turn reports around faster, but do not cut it close.

Frequently asked questions

Will a board of equalization reject my appeal if I only submit a CMA?

Not automatically. Most boards accept a CMA as market evidence, but they may give it limited weight next to a certified appraisal. The outcome hangs on how well-documented the comps are, whether the assessor objects, and your state's evidence rules. A CMA paired with a solid comp grid built from public sales data beats a CMA alone.

Can a real estate agent sign a letter of opinion of value instead of a formal appraisal?

Yes. Some boards accept a signed broker price opinion (BPO) or letter of value from a licensed agent as informal evidence. It is not a USPAP-compliant appraisal, and most formal review boards treat it accordingly. For informal hearings or small-dollar appeals, a signed letter from a knowledgeable local agent can move the needle.

How many comparable sales should I include in my appeal evidence?

Three to five tight comps beat ten loose ones. Boards respond to a small set of truly similar sales with clear explanations. More comps only help if they are genuinely comparable. A pile of questionable ones invites challenges and dents your credibility.

Does a Zillow estimate work as evidence in a property tax appeal?

You can submit it, but it gets very little weight. Zillow's Zestimate is an automated valuation model with no property inspection, no adjustment documentation, and no professional accountability. Assessors and boards know its limits. Zillow itself states the Zestimate is not an appraisal. Use it as a rough sanity check, not as hearing evidence. ^[11]

What is the difference between a CMA and a broker price opinion (BPO)?

A BPO is more formal than a CMA, usually prepared for a lender or bank by a licensed agent or broker. It often involves a physical inspection and a written report with documented adjustments. Some states regulate BPOs separately. For tax appeals, a BPO carries slightly more credibility than a standard CMA but still less than a certified appraisal.

Can I use a CMA from Redfin or Realtor.com instead of one from a local agent?

These platforms generate automated CMAs from MLS data, but they have no professional signature behind them and no adjustment methodology. They are weaker than an agent-prepared CMA for appeals. If you use one to spot comparable sales, verify those sales in the public deed record and present the deed data as your actual evidence.

How do I find the assessment date my comps need to be close to?

Check your assessment notice or your state's property tax code. Most states assess as of January 1 of the tax year. California uses a lien date of January 1. Texas uses January 1. Florida uses January 1. New York varies by municipality. Your county assessor's website almost always states the valuation date in the appeal instructions.

If my assessed value is only 5 percent over market, is it worth appealing?

Run the math first. Take the dollar overassessment, multiply by your effective tax rate, and see the annual savings. A 5 percent overassessment on a $300,000 home is $15,000, which at a 1.1 percent rate saves about $165 a year. Whether that justifies your time and any evidence cost is your call. Many boards also require a minimum percentage discrepancy before they adjust, so check local rules.

Do I need to hire an attorney or contingency firm to present evidence at an appeal hearing?

No. Most residential appeal boards are built for self-represented homeowners. You do not need an attorney, and you do not need to pay a contingency firm a cut of your savings. Preparing your own comp grid and showing up is straightforward in most jurisdictions. Contingency firms mainly make sense for commercial properties with very large tax bills.

Can the assessor use my CMA against me to raise my assessment?

In rare cases, yes. If your CMA shows a higher value than the current assessment and you submit it, the assessor could point to it as support for holding or raising the value. Review every document before you hand it over. Never submit a CMA without confirming it supports a reduction.

What happens if my appeal is denied even with good evidence?

You can usually escalate. Most states allow a further appeal to a state administrative body or to the courts after a board decision. In Texas, you can file suit in district court. In New York, you can file a Small Claims Assessment Review (SCAR) for residential properties. Deadlines for further appeals are short, typically 30 to 90 days after the board's decision, so act fast.

Is a CMA useful for appealing commercial property tax assessments?

Rarely. Commercial valuation typically uses income capitalization or a sales comparison approach based on commercial comps, neither of which a residential CMA addresses. For commercial appeals, a certified MAI-designated appraiser's report is the practical standard. The dollar stakes on commercial property almost always justify that cost.

Sources

1. The Appraisal Foundation, USPAP overview: USPAP is published by the Appraisal Foundation under authorization from FIRREA and governs certified appraisers' methodology and liability
2. Texas Legislature, Texas Property Tax Code Chapter 41: Texas Property Tax Code Section 41.43 states the appraisal district bears the burden of establishing value by a preponderance of the evidence once the taxpayer presents qualifying evidence; Section 41.45 governs ARB hearing scheduling within 55 days
3. New York City Tax Commission, evidence requirements for assessment appeals: NYC Tax Commission states appraisals must be prepared by a New York State licensed or certified appraiser to receive full evidentiary weight in a formal appeal
4. Cook County Board of Review, appeal procedures: Cook County Board of Review accepts market evidence broadly but appraisals carry significantly more weight in contested hearings
5. Maryland State Department of Assessments and Taxation: Maryland publishes assessment data and comparable sales online, enabling Montgomery County homeowners to build a comp grid from official sources
6. Appraisal Institute, residential appraisal cost guidance: A residential appraisal from a certified appraiser typically costs $300 to $500 for a standard single-family home, with higher costs in complex or high-cost markets
7. Lincoln Institute of Land Policy, 50-State Property Tax Comparison Study 2023: The U.S. median effective property tax rate on owner-occupied housing is approximately 1.1 percent, per Lincoln Institute analysis
8. Hennepin County, Minnesota, property tax appeals: Hennepin County, Minnesota addresses commercial evidence standards in its property tax appeals process
9. Florida Legislature, Florida Statute 194.034, Value Adjustment Board hearings: Florida Statute 194.034 states that the petitioner may present testimony and other evidence relevant to the assessed value without prescribing a specific form of evidence
10. Georgia General Assembly, O.C.G.A. Section 48-5-311, county Board of Equalization: Georgia O.C.G.A. Section 48-5-311 allows taxpayers to present evidence before a county Board of Equalization without mandating a certified appraisal
11. Zillow, Zestimate methodology FAQ: Zillow states that the Zestimate is not an appraisal and should not be used in place of one