Four numbers for one home: CMA, appraisal, assessed value and online estimates

Who produces each number, what it is for, why they rarely match, and which one to look at when you price, offer, borrow or pay tax.

Home value · Last updated 2026-10-29

Key points

A CMA is an agent’s opinion of the likely sale price, built from recent comparable sales. Massachusetts lets agents give one for a listing, purchase or sale, as long as it is not called an appraisal.
The lender’s appraisal is ordered by the lender and decides how much the bank will lend. You are entitled to a free copy.
The assessed value is the town’s mass valuation as of January 1, made for tax. It lags the market and can contain record errors, so it is a weak guide to price.
Online estimates come from computer models that never walk through the house. Use them to raise questions, then check the facts and the sales behind any number.

The agent’s CMA: an opinion of likely sale price

A comparative market analysis (CMA) starts from homes like yours that sold nearby in recent months, then adjusts for the differences: size, condition, parking, floor, outdoor space, and how the market has moved since each sale. Active and pending listings show the competition a buyer sees today. The result is a range and a reasoned estimate, used to set a list price or decide what to offer.

Massachusetts law keeps this separate from an appraisal. The appraiser licensing statute does not apply to a real estate broker or salesperson who gives an opinion of price for a prospective listing, purchase or sale, provided the opinion is not referred to as an appraisal. A CMA is professional advice, and its quality depends on which sales were chosen and how honestly the differences were weighed.

Ask the agent to show the work: which sales, why each was chosen, and what was adjusted. A good CMA also says what would move the number, such as a slow spring market or a condition problem found at inspection. Our guide to choosing comparables explains how the sales are picked.

The lender’s appraisal: the number the loan is based on

When you finance a purchase, the lender engages a licensed or certified appraiser. For loans secured by your principal dwelling, federal rules require the appraiser’s judgment to be independent: no one may pressure the appraiser toward a value, and the appraiser’s pay cannot depend on the loan closing.

For a Fannie Mae purchase loan, the property value used in the loan-to-value ratio is the lower of the sales price or the appraised value. If the appraisal comes in below the price, the loan is sized to the appraisal, and you either cover the difference or renegotiate. Under Regulation B you receive a free copy of every appraisal for a first-lien loan on a dwelling, promptly after it is completed or three business days before closing, whichever is earlier.

An appraisal looks back at closed sales, so it can trail a market that is moving quickly. What to do with a low result is in our guide to the lender’s appraisal.

Assessed value: the town’s number for tax

Massachusetts assessors determine the fair cash value of every property as of January 1, and the tax bill is the assessed value multiplied by the tax rate. These are mass appraisals: the city values thousands of properties at once from sales data and its own record of each building.

That makes the assessed value useful for two things: estimating property tax, and checking what the city has on file about a home, such as living area, rooms, year built and lot size. In Boston those records are on the Assessing Department’s property lookup.

As a guide to price it is weak. By the time you read it, the valuation date may be many months old, a renovation may not be recorded, and the record may simply be wrong. If your own assessment looks too high, see our guide to assessments and abatements.

Online estimates: automated models

Value estimates on real estate websites come from automated valuation models (AVMs), software that predicts value from public records, listing data and past sales. Federal rules require mortgage lenders that use AVMs to decide collateral value to adopt quality control standards, and under the appraisal independence rules a value produced only by an AVM does not count as a valuation.

An AVM never walks through the house. Unless the data says so, it cannot see a new kitchen, a leaking roof, a dark garden-level unit or a deeded parking space, and many public records are updated late. Two websites can give the same home very different numbers.

Treat an online estimate as a prompt for a question. If it is far from the asking price, look for the facts or the sales that explain the gap.

Why the numbers differ, and which one to use

The four numbers answer different questions, refer to different dates and rest on different evidence. Some gap between them is normal. A large gap is a reason to look harder at the facts.

Number	Who produces it	Valuation date	Use it for
CMA	Your agent	Today’s market	Setting a list price; deciding an offer
Lender’s appraisal	A licensed or certified appraiser engaged by the lender	The effective date in the report	The loan amount; an independent check on price
Assessed value	City or town assessors	January 1 before the fiscal year	Property tax; checking the city’s records
Online estimate	A website’s automated model	Whenever the model last updated	A quick first look; spotting questions

Before you rely on any number

Whichever number you are looking at, the same checks apply.

Check the facts behind it: living area, bedrooms, baths, parking and condo fee, against the listing and the assessor’s record.
Ask which closed sales support it, and when they closed.
Note the date the number refers to, and what has happened in the market since.
For a purchase, keep three things apart: what the market supports, what the seller hopes for, and the most you are prepared to pay.

General information for Massachusetts buyers and owners, current as of the date shown. It is not an appraisal or legal advice. For a loan, the lender and its appraiser determine value; for tax questions, contact your city or town assessors.