In short
The municipal assessment is not market value: it is a taxation tool, frozen for three years in Quebec and based on a reference date eighteen months before the roll takes effect — Ontario stayed on 2016 values for nearly a decade. To roughly update it: multiply the assessment by the comparative factor published by your municipality (e.g. 1.12 = sales ~12% above the roll). For a real value — financing, estate, assessment challenge — you need a professional appraiser (É.A. in Quebec, AACI/CRA elsewhere).
Why the municipal assessment is not market value
"The house is listed $120,000 above the municipal assessment — that's robbery!" It is probably real estate's most widespread confusion. The municipal assessment is a taxation tool: it distributes the tax burden across a municipality's properties — it does not say what yours is worth on today's market.
Two structural reasons widen the gap. It is frozen: in Quebec, the assessment roll is deposited for three years, and its values reflect the market at an earlier reference date — eighteen months before the roll takes effect. A property assessed on the market of two or three years ago, in a rising market, will mechanically look "under-assessed". It is mass-produced: thousands of properties valued through statistical methods, without visiting yours — your renovations, your yard, your light are not in it. Ontario pushes the logic to the extreme: MPAC assessments remained based on January 1, 2016 values through nearly a decade of successive postponements.
The comparative factor: the correction tool almost nobody knows
Quebec actually publishes the tool to correct for this: the comparative factor. Every year, for every municipality, this factor measures the gap between roll values and the real market (based on observed sales). A factor of 1.12 means properties sell, at the median, about 12% above their roll value. Multiplying the municipal assessment by the comparative factor therefore gives a rough indication of updated value — exactly what the calculator below does. (Elsewhere in Canada, you can apply your own ratio between recent local sales and assessments.)
The key word is "rough": the factor is a municipal average. It knows nothing about your street, the state of your roof or your kitchen renovation. It is an order of magnitude to frame a discussion — not a value to buy, sell or borrow against.
Interactive tool
From the municipal roll to a value indication, in 20 seconds
Enter your municipal assessment and the comparative factor published by your municipality: the calculator returns the value indication and the gap with an asking price.
The comparative factor is a municipal average: this indication frames a discussion — it replaces neither a market analysis nor a professional appraiser's report. Outside Quebec, use your own local sales-to-assessment ratio.
When a professional appraiser is required — and which credential to verify
To know the real market value of a specific property, on a specific date, there is a professional whose job that is: the professional appraiser — in Quebec, the É.A. (member of the Ordre des évaluateurs agréés du Québec); elsewhere in Canada, the AACI and CRA designations of the Appraisal Institute of Canada. Their signed, defensible report visits the property, analyzes comparable sales and documents every adjustment.
The situations where one is required: financing (lenders often demand it, especially for a refinance); estates and divorce (a neutral, defensible value avoids many conflicts); challenging your municipal assessment (an appraiser's report is the centrepiece of a review request); and selling without a broker, where mispricing costs far more than the report. How to verify the credential? Our pillar Verify a professional points to the order or association, province by province.
Frequently asked questions
Why is the asking price above the municipal assessment?
Because the municipal assessment is a taxation tool, frozen for three years in Quebec and based on an earlier reference date (eighteen months before the roll takes effect). In a rising market, the gap is mechanical — by itself, it says nothing about whether the price is reasonable.
What is the comparative factor?
A coefficient published every year for each Quebec municipality, measuring the median gap between roll values and actual sale prices. Municipal assessment × comparative factor = a rough indication of updated value. It is a municipal average: useful for framing, insufficient for deciding. Elsewhere, apply your own local sales-to-assessment ratio.
When do I need a professional appraiser?
Financing and refinancing (often required by the lender), estates, divorce, challenging your municipal assessment, selling without a broker. Their signed report establishes the market value of a specific property on a specific date — something no municipal roll or online tool does.
Which credential should an appraiser hold?
In Quebec: chartered appraiser (É.A.), member of the Ordre des évaluateurs agréés du Québec. Elsewhere in Canada: the AACI (all property types) or CRA (residential) designations of the Appraisal Institute of Canada. The credential can be verified with the order or association.
Mechanisms verified (triennial roll, reference date, comparative factor) in 2026 — municipal rules evolve: confirm with your municipality or a professional appraiser.
Go further
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