No two houses are the same, which means no comparable sale is ever a perfect match for the property you're pricing. Adjusting for the differences is not optional — it's the entire discipline. The problem is that the same technique that makes a CMA credible can just as easily be used to walk a raw sale price backward into whatever number a client wants to hear, and the line between the two is a professional-conduct question, not a math question.
Key takeaways
A comparable sale is useful precisely because it is close, not because it is identical — and it is never identical. Lot size, condition, finishes, a garage, a busier street, a more recent sale date: every one of those differences has to be converted into a dollar adjustment before a raw sold price can say anything useful about the property actually being priced. That conversion is the real work of a CMA. It is also the exact point where a number can be steered rather than derived, which is why the mechanism itself carries a professional-conduct dimension most agents never have named for them.
CREA's own reasoning for building the MLS® Home Price Index instead of just publishing raw prices is the same reasoning that governs a single-property CMA. As CREA puts it: “average or median prices can change a lot from one month to the next and paint an inaccurate or even unhelpful picture of price values and trends” — which is exactly why the HPI is built instead to track “a ‘typical’ home based on the features of homes that have been bought and sold” rather than a simple average. A raw comparable sale is the single-property version of a raw average price: informative, but only after the specific ways it differs from the subject property have been priced out.
The adjustment logic itself is standard appraisal theory, not a CREA or RECO invention: identify what actually differs between the comparable and the subject — lot size, above-grade square footage, bedroom and bathroom count, garage, basement finish, condition, and sale recency — and adjust the comparable's price to what it would have sold for if it had the subject's features instead of its own. A comparable that sold for more because it had a finished basement is adjusted down before it is used to support the subject's value; one that sold for less because it back onto a busier road is adjusted up. The adjustment always moves the comparable toward the subject, never the other way around, and every adjustment should be traceable to a specific, named difference — not a round number chosen because the total needed to land somewhere.
CREA's REALTOR® Code has a defined term for what a CMA produces, and it is worth knowing precisely because it sets real limits. An “Opinion of Value… means an estimate of the value of specified interests in, or aspects of, identified real estate which may be based wholly or partly on comparative market analyses. An Opinion of Value may contain more or less analysis of relevant data than an appraisal and may be performed by a REALTOR®” — a CMA-based Opinion of Value is a recognized, legitimate category, and it is explicitly distinct from a formal appraisal.
The Code attaches real conduct rules to it. A REALTOR® “shall not provide an Opinion of Value if it is outside the REALTOR®'s field of expertise… unless this fact is disclosed in writing”, must disclose any present or contemplated personal interest in the property before valuing it, and — the rule most directly on point for the fudging question — “fees charged for Appraisals or Opinions of Value shall not be based on the amount of value reported”. That last rule targets the exact incentive structure that produces a steered number: if what you're paid depends on the figure you land on, the figure stops being an analysis and becomes a negotiating position dressed up as one. The same Code separately requires that a REALTOR® “shall not intentionally mislead anyone as to any matters pertaining to a property” — a standard a reverse-engineered CMA fails directly, regardless of how the arithmetic is dressed up.
It is worth being precise about where the regulatory floor actually sits, because there is not a prescribed provincial method to fall back on. RECO's own published material describes the TRESA framework's disclosure and conduct obligations in detail, but no RECO bulletin sets out a required CMA methodology — how many comparables, how far back they can date, or what adjustment method to use is professional practice guidance, not a regulatory requirement, which is precisely why the ethical line has to be enforced by the agent's own discipline rather than a checklist. How many comparables a defensible CMA actually needs and how far back a comparable can reasonably date are answered in more depth elsewhere on this site; the point here is narrower — whatever method is used, it has to be applied consistently rather than selectively.
The honest version of the process starts from the comparables and ends at a number. The dishonest version starts from a number — a listing price the seller wants, or a purchase price a buyer needs to justify — and works backward, selecting comparables and adjustment sizes until the total arrives where it was always going to. Both processes can produce a document that looks identical on the page: a table of comparables, a set of adjustments, a concluded value. The difference is entirely in which direction the reasoning ran, and it shows up in a specific, checkable way: can every adjustment be justified on its own, against the actual physical or market difference it corresponds to, without reference to what total is needed? An adjustment that only makes sense once you know the target number is the fudge, however precisely it's stated.
A concrete test worth applying to your own work: pick the single largest adjustment on the sheet and explain it out loud to someone who has not seen the target price. If the explanation is a real, specific difference — “this comp has a two-car garage the subject doesn't, worth roughly $18,000 in this submarket based on the last three garage/no-garage pairs” — it holds up. If the explanation is some version of “that's what it needed to be to get to the number,” it doesn't, and no amount of formatting fixes that.
No verified Canadian source publishes one, and treating a rule-of-thumb percentage as a fact rather than a locally-derived estimate is itself a form of fudging. The defensible approach is deriving the adjustment from actual paired sales in the specific submarket — two otherwise-similar comparables that differ mainly on the one feature — not importing a generic figure.
No. RECO's published material addresses disclosure and conduct around price opinions, not CMA methodology itself. The number and recency of comparables is a matter of professional judgment, which is exactly why that judgment has to be exercised honestly.
Some do, and CREA's REALTOR® Code permits it — with one explicit condition: the fee cannot be based on the value reported. A fee structure that pays more for a higher opinion of value creates exactly the incentive the fudging question is about.
A quick review can confirm the comparables and adjustments actually hold up on their own.
