Home Valuation in Maryland: AVMs, CMAs, and Appraisals

By Adam Chubbuck, Team Leader, Team Alpha Charlie of Douglas Realty. Retired U.S. Navy Chief. Licensed in Maryland and Virginia.

There are three ways to put a number on a Maryland house, and they are not competing versions of the same thing. They are three different instruments built for three different jobs, and most of the confusion I see from homeowners comes from using one to answer a question it was never designed to answer.

An automated estimate is a statistical guess. A comparative market analysis is a professional pricing opinion. An appraisal is a regulated valuation prepared for a lender. Different inputs, different purposes, different accuracy, and very different consequences if you rely on the wrong one.

Here is how each one actually works and when each is the right tool.

Instrument One: The Automated Valuation Model

What it is

An AVM is an algorithm. It ingests public tax records, prior sale prices, square footage, bed and bath counts, lot size, and recent nearby sales, and it produces a number. Zillow’s Zestimate is the best known, but Redfin, Realtor.com, Movoto, and most bank portals run their own.

It costs nothing, it takes two seconds, and it never sets foot in your house. That last part is the whole story.

What it does well

It gives you a rough order of magnitude, and it does that instantly. In dense subdivisions of similar homes built in the same decade with similar finishes, AVMs perform reasonably well, because that is exactly the condition their statistics assume: lots of comparable data, little variation between properties.

It is also genuinely useful for tracking direction over time. Whether your neighborhood is trending up or down is a question an AVM answers acceptably.

Where it fails, and Maryland gives it plenty of chances

It cannot see your house. It does not know your kitchen was renovated last year, or that your roof is at end of life, or that your basement takes on water every spring, or that you added a bathroom without pulling a permit. Two houses with identical public records and a $150,000 condition difference get similar estimates.

It cannot see your surroundings. It does not know you back to a commercial parking lot, or that the house next door has been vacant for three years, or that your street is a cut-through.

It breaks on water. This is the big one in Anne Arundel County. AVMs cannot evaluate water depth at mean low water, pier condition, whether frontage is protected or exposed, or the difference between true waterfront, deeded community water access, and a water view with no rights at all. Those distinctions are worth hundreds of thousands of dollars on this peninsula and an algorithm reads them as approximately the same thing.

It breaks in heterogeneous markets. Look at what the published sources reported for Severna Park in 2026 and you can see the problem in one glance. Zillow’s Home Value Index put the average Severna Park home value at $723,849, up 2.1 percent year over year. Redfin reported a $795,024 median sale price for May 2026, up 15.5 percent. Movoto reported an $825,000 median list price in August 2026 at roughly $311 per square foot. And Redfin reported a $717,500 median for November 2025, down 2.8 percent.

That is a spread of over $100,000 across four sources covering the same community. None of them are lying. They are measuring different things across a market whose actual sales in spring 2026 ranged from $635,000 ranchers to a $4,050,000 waterfront on Boone Trail. Any single number that has to cover that distribution is going to be a poor guide to your specific house.

Pasadena shows the same pattern at a different price point. Published 2026 figures for the 21122 zip code ranged from a $406,500 median reported by Orchard to $421,312 from Zillow to $464,000 from PropertyIQ.

When to use it

Casual curiosity. Watching a trend. Setting an initial expectation before you talk to anyone. That is the honest list.

When not to use it

Setting a list price. Deciding whether to sell. Making an offer. Planning your finances around your equity. Disputing a tax assessment. Any decision where the number needs to be right.

Instrument Two: The Comparative Market Analysis

What it is

A CMA is a licensed agent’s pricing opinion, built from actual MLS sales data and informed by having seen your property. In this market that means Bright MLS, which contains the data the public sites only partially receive.

A real CMA involves selecting genuinely comparable recent sales, adjusting for the differences between those properties and yours, examining what is currently active and pending in your competitive set, and applying judgment about what your specific market is doing right now.

What makes it more accurate than an AVM

It uses complete data. Bright MLS carries days on market, price change history, concessions, financing type, and settlement terms. A closed sale at $500,000 where the seller paid $15,000 in buyer closing costs is not the same as a clean $500,000 sale, and only the MLS record tells you that.

It sees the property. Condition, layout, finishes, and functional quirks that no algorithm can capture. Whether the fourth bedroom is a real bedroom or a converted closet.

It sees the competition. An appraisal looks backward at closed sales. An AVM looks at statistics. A CMA also looks at what a buyer will be comparing you against next weekend, which is what actually determines whether you sell.

It applies local judgment. Whether a Berrywood community pier conveys, which side of a school attendance boundary an address falls on, whether a Pasadena community has deep water or three feet at low tide. These are the differences that move price in this corridor, and they require someone who works here.

What it is not

A CMA is an opinion, not a certification. It is not accepted by a lender as collateral valuation, it does not satisfy an estate or divorce requirement, and a competent agent can produce a defensible CMA that lands somewhat differently from another competent agent’s. That is normal. Valuation is judgment, not arithmetic.

When to use it

This is the workhorse and it covers most homeowner needs: pricing a listing, deciding whether to sell, evaluating an offer, understanding your equity position, planning a move, testing whether a renovation makes financial sense, or preparing to challenge a property tax assessment.

Instrument Three: The Formal Appraisal

What it is

An appraisal is a written valuation prepared by a state licensed or certified appraiser under the Uniform Standards of Professional Appraisal Practice. It is a regulated work product with a defined scope, a defined methodology, and professional liability behind it.

In a purchase transaction, the critical thing to understand is who the appraiser works for. Even when the buyer pays for it, the appraiser’s client is the lender, and the purpose is to confirm that the property adequately secures the loan. The appraiser is not there to tell you whether you got a good deal.

How it works

The appraiser inspects the property, measures it, notes condition and quality of construction, then selects closed comparable sales and makes line item adjustments for differences in size, condition, age, lot, location, and amenities. The result is a supported opinion of value with the reasoning documented.

Typical cost in this market runs a few hundred dollars for a standard single family residence and materially more for complex properties, waterfront, or unusual construction. Turnaround is commonly one to two weeks depending on appraiser availability.

What it is uniquely good for

Anything requiring a defensible, independent number. Mortgage underwriting, refinancing, removing PMI, estate settlement, divorce, bankruptcy, litigation, tax appeals at a formal level, and gift or charitable transfers. If a third party has to accept the number, you need an appraisal.

Its structural limitation

An appraisal is inherently retrospective. It is built from sales that have already closed, which in Maryland means data that is typically 30 to 90 days old by the time it is used. In a market moving quickly in either direction, an appraisal lags what is actually happening.

That lag is exactly why appraisals sometimes come in below a contract price in a competitive market. It is not usually an error. It is a measurement of a slightly earlier moment.

The Three Side by Side

Which One Answers Your Question

• “I’m just curious what my house is worth.” AVM, then a CMA if the number matters to you.
• “Should I sell this year?” CMA. You need a real number and a real read on your competition.
• “What should I list at?” CMA, always. This is the single highest stakes number in the entire transaction and it is not an algorithm’s job.
• “Is this offer fair?” CMA.
• “How much equity do I have for planning purposes?” CMA is plenty. Appraisal only if a lender or attorney is involved.
• “Can I drop my PMI?” Appraisal, and check your servicer’s specific requirements first.
• “I’m refinancing.” Appraisal, ordered by your lender.
• “We’re settling an estate or a divorce.” Appraisal, without exception. Do not try to shortcut this one.
• “My tax assessment looks wrong.” Start with a CMA to see whether you have a case, then escalate to an appraisal if the dollars justify it.
• “My appraisal came in low on my sale.” That is its own problem with its own playbook, and it is worth a separate conversation.

Where to Start

For most Maryland homeowners the right sequence is simple: get a free number to set expectations, then get a real one before you make a decision.

That is exactly what my team’s free Maryland home valuation is built for. It is not an algorithm that has never seen your street. It comes from someone who works this corridor daily, has access to complete Bright MLS data, and knows the difference between a Round Bay community pier and a private pier on the Magothy. There is no obligation and no expectation that you are selling. Plenty of the valuations I run are for people who just want to know where they stand.

If you are in Anne Arundel County, Howard County, Baltimore County, Baltimore City, or the surrounding markets, reach out to Team Alpha Charlie of Douglas Realty and I will tell you what your house is actually worth, and what it would take to get there.

Maryland Home Valuation FAQ

Are Zillow Zestimates accurate in Maryland?

They are directionally useful and not reliable for decisions. AVMs cannot see condition, renovations, or surroundings, and they perform particularly poorly on waterfront and water privileged property where value turns on water depth, pier condition, and deeded access rights. The scale of the problem shows in the disagreement between sources: published 2026 figures for Severna Park ranged from $717,500 to $825,000 across four different providers. Zillow publishes its own accuracy statistics and they are worth reading before you rely on a Zestimate.

Is a CMA the same as an appraisal?

No. A CMA is a licensed agent’s pricing opinion built from MLS data and a property visit, usually free, forward looking because it includes active competition, and not accepted by lenders or courts. An appraisal is a regulated work product prepared by a licensed appraiser under USPAP standards, costs several hundred dollars or more, looks backward at closed sales only, and is accepted by lenders and courts.

How much does a home appraisal cost in Maryland?

A standard single family residential appraisal typically runs a few hundred dollars, with waterfront, unique construction, and complex properties costing meaningfully more. Turnaround is commonly one to two weeks depending on appraiser availability in your area.

Do I need an appraisal to sell my house?

No. As a seller you do not order an appraisal. If your buyer is financing, their lender will order one, and if the buyer is paying cash there may be no appraisal at all. What you need to sell is an accurate CMA to set your list price.

Why do online estimates differ so much from each other?

Because they use different data sources, different algorithms, and different definitions. Some report median sale price, some median list price, some an automated valuation index. Some include new construction and some do not. In markets with wide price distributions, like Severna Park where 2026 sales ranged from the $600,000s to over $4 million, any single aggregate number is a poor description of any specific house.

Can I use a CMA to appeal my Maryland property tax assessment?

It is a reasonable starting point for determining whether you have a case, and it may be persuasive in an informal appeal. For a formal appeal where the dollars are significant, a full appraisal carries substantially more weight. Start with the CMA to see whether the gap justifies the appraisal expense.

Sources and Dates

Figures cited above are attributed to their published source and reporting period: Redfin market data for Severna Park, reporting periods November 2025 and May 2026, plus individual sold records from spring 2026. Zillow Home Value Index for Severna Park and the 21122 zip code. Movoto Severna Park market trends, August 2026. Orchard 21122 market report, trailing 30 day period. PropertyIQ 21122 market data through June 2026. All market figures change monthly and describe aggregates rather than specific properties. Appraisal costs and turnaround times vary by property, complexity, and appraiser availability. This article is general information and not legal, tax, or appraisal advice.

Let’s Talk About Your Move

If you want to know what your Maryland home is actually worth, skip the algorithm and start with a real number. Send me the address and I will pull the comps, look at what you are competing against, and tell you where you stand. No obligation, and no assumption that you are selling.

I am Adam Chubbuck, Team Leader of Team Alpha Charlie of Douglas Realty. I am a retired U.S. Navy Chief, a licensed Real Estate agent in Maryland and Virginia, and I have closed more than 350 homes over the past five years across the Baltimore to Annapolis corridor. My team serves buyers and sellers throughout Anne Arundel County, Howard County, Baltimore County, Baltimore City, and the surrounding markets, with deep experience supporting military, veteran, and Department of Defense families. I also run Enclave Property Management out of Pasadena, Maryland, so I see this market from the ownership side as well as the sales side.

If you are weighing a move, start with a real conversation and real numbers. Reach me directly at 443-347-6692, email [email protected], or start at TACMD.com.

Adam Chubbuck
Team Leader, Team Alpha Charlie of Douglas Realty
Douglas Realty | Licensed in MD and VA
443-347-6692 | [email protected] | TACMD.com

Smile more,
Adam Chubbuck