How to appeal your property assessment in Ontario: the complete guide

Who assesses, and as of which date

In Ontario, one organization assesses every property: the Municipal Property Assessment Corporation (MPAC). In its own words, MPAC "determines property assessments for all properties in Ontario." Municipalities then set their tax rates, and the province sets education tax rates.

MPAC estimates current value. Section 1 of the Assessment Act defines it as the amount the property would realize "if sold at arm's length by a willing seller to a willing buyer."

That value is fixed as of a set date. For the 2026 tax year, it is still January 1, 2016. MPAC says so plainly: "Property assessments for the 2026 property tax year will continue to be based on fully phased-in January 1, 2016 current values." The deadline guide explains why.

How long do you have to appeal?

The general rule is in section 39.1 (1.1) of the Assessment Act: a Request for Reconsideration "must be made no later than March 31 of the taxation year." For the 2026 tax year, MPAC confirmed a March 31, 2026 deadline. MPAC adds that each year's deadline is printed on your Property Assessment Notice.

A second rule applies if you receive a Property Assessment Change Notice (PACN), for example after a renovation or an addition. You then have 120 days from the Issue Date printed on the notice (s. 39.1 (3)). You do not pick between the two: March 31 is the general rule, and 120 days applies to a change notice.

The steps, in order

MPAC suggests starting with one question: "Could I have sold my property on January 1, 2016 for the assessed value stated on my Notice?" If yes, no action is needed. If no, here is what to do.

• Find your notice. It shows your Roll Number, your Access Key and your reconsideration deadline.
• Log in to AboutMyProperty, MPAC's free tool. It shows the data MPAC used (building size, lot size, age) and values of properties in your area.
• Check the data. Wrong data is a ground MPAC names outright: "The property data on your Notice of Assessment or on MPAC AboutMyProperty is incorrect."
• Gather evidence: comparable sales around January 1, 2016, assessments of similar properties, photos, repair estimates. See evidence that works.
• File the Request for Reconsideration online in AboutMyProperty, or by mail with the form. The Act requires it to set out "the basis for the person's request and all relevant facts" (s. 39.1 (4)).
• Wait for MPAC's written decision, then decide whether to go to the Assessment Review Board.

Reconsideration comes before any appeal

If your property is classified residential, farm, managed forest or conservation land, you cannot go straight to the tribunal. MPAC explains: "you must file a Request for Reconsideration with MPAC – and MPAC must make a decision before you are eligible to appeal." Section 40 (3) of the Act sets this condition.

Other properties, such as commercial or industrial ones, may choose between a reconsideration and a direct appeal to the Assessment Review Board, by March 31 or 120 days from the date of another type of notice, according to the ARB.

What it costs

A Request for Reconsideration is free: MPAC reviews it "free of charge." If you then go to the Assessment Review Board (ARB), the filing fee is $132.50 per roll number for residential, farm, managed forest and conservation land properties, and $318 for other properties. The ARB takes $10 off when you e-File. Details and the savings calculation are in cost and savings.

What works, and what does not

MPAC lists useful evidence: sales of comparable properties, assessed values of comparable properties, recent appraisals, zoning, photos and estimates for significant repairs. One Ontario feature stands out: the Assessment Act tells the ARB to look at how similar properties nearby are assessed and to adjust your assessment for equity if that lowers it (s. 44 (3)).

On the other hand, the amount of your taxes is not a ground the Act provides. The grounds in section 40 (1) cover value, classification and who is on the roll. MPAC reminds owners that "your property assessment and the property taxes you pay are not the same thing." A 2025 sale carries little weight, because the question is about January 1, 2016.

After you file

The Act gives MPAC 180 days to respond, or 240 days if it tells you within 180 days that it needs an extension (s. 39.1 (7)). In 2026, MPAC reports delays on some requests. If it adjusts the value, it sends a new notice and asks you to sign Minutes of Settlement, which go to your municipality.

If you still disagree, you have 90 days from the issue date of the decision to appeal to the ARB (s. 40 (5)). The after you appeal guide covers the hearing and when an appraiser helps.

The risk to know: your value can also go up

A reconsideration reopens the file. The Assessment Act provides that the outcome of a reconsideration or appeal can "increase, reduce or otherwise alter the assessment" (s. 39 (6)), and that the ARB may reopen "the whole question of the assessment" (s. 44 (1)). MPAC itself invites a request if you believe the value is "too high or too low." Before you file, make sure everything on your property is in MPAC's records.

To compare your assessment with today's market price, see municipal assessment vs market value. For other provinces, see the property assessment section.

Frequently asked questions