How to Appeal Your Property Assessment in Ontario

The short answer

In Ontario, you do not start at a tribunal — you start with MPAC itself. File a free Request for Reconsideration (RfR) with the Municipal Property Assessment Corporation, and only if that decision still leaves you unsatisfied do you appeal to the independent Assessment Review Board. For a home, a farm, or managed forest land, the RfR is not optional: MPAC must decide it before you can appeal at all. The deadline that matters most is printed on your own Property Assessment Notice — usually March 31 of the tax year for the annual notice — and the Board appeal must be filed within 90 days of MPAC's decision letter.

Why the 2016 valuation date matters

Ontario is between province-wide assessment updates, and assessed values are still based on a January 1, 2016 valuation date. That changes what a good challenge looks like. Arguing that your home would sell for more or less today misses the test: the question is whether your assessed value is right as of January 1, 2016 and consistent with similar properties. The strongest RfRs compare like with like — your assessed value against the assessed values of comparable homes in your neighbourhood — rather than against current sale prices.

MPAC assesses and classifies more than 5.7 million properties across Ontario, and its assessments are the foundation municipalities use to calculate property taxes. Your assessment does not set your tax rate; it sets your share of the municipal tax burden. A successful challenge lowers your assessed value, which lowers your share — it does not change the rate itself.

Step 1: Read your notice and diary the deadline

Your Property Assessment Notice (PAN) carries three things you need: your 19-digit roll number, your access key for MPAC AboutMyProperty, and your RfR deadline. MPAC states the deadline on the notice itself, and the usual pattern is March 31 of the tax year for the annual notice, or 120 days from the notice date for other notices such as a Property Assessment Change Notice. The date on your notice wins over any general date in this guide — diary it the day the notice arrives, because the deadline cannot be waived.

Check the notice for errors as well as value. Wrong building size, wrong lot area, a classification that does not match how the property is used, or a portion of the property listed under the wrong class are all valid reasons to file — and they are often easier to prove than a value dispute.

Step 2: Compare your property on AboutMyProperty

Before you file, register for MPAC AboutMyProperty with the roll number and access key from your notice. The free tool lets you view your property details, compare your assessed value with similar properties nearby, access your notices online, and file the RfR itself. Build your case from the comparisons: note the assessed values of genuinely similar homes — similar size, age, lot, and neighbourhood — and note any differences in your property's recorded details that would justify a lower value, such as condition issues or a smaller finished area than MPAC has on file.

Step 3: File the free Request for Reconsideration

File the RfR online through AboutMyProperty — MPAC calls it the fastest way to start a review, and it lets you attach documents, photos, and reports and check the status of your request. You can also file by mail with an RfR form from MPAC's website, or by letter including your 19-digit roll number, full name, address and phone number, your property-specific reasons, and supporting documentation.

MPAC lists these as reasons to file: you believe your assessed value is too high or too low; the property data on your notice or on AboutMyProperty is incorrect; you believe your classification should be different; the portions of assessed value across property classes are wrong; or you received a Property Assessment Change Notice you believe is incorrect. Attach the evidence that fits your reason — sale information for your property and similar properties, assessed values of comparable properties, recent appraisals, photos, zoning information, or estimates for significant repairs.

You can file an RfR if you are the property owner, received a Property Assessment Notice, or are the owner's representative. There is no charge.

Step 4: Appeal to the Assessment Review Board if needed

If MPAC's decision does not satisfy you, appeal to the Assessment Review Board (ARB), an independent tribunal of the Ontario Ministry of the Attorney General with its own appeal process. You have 90 days after MPAC notifies you of its RfR decision to file, and the deadline is stated in the letter MPAC sends with the results. For residential, farm, and managed forest properties, MPAC must have decided the RfR first; business properties may file a Notice of Appeal directly with the Board without an RfR.

The filing fee is $132.50 per roll number for residential, farm, and managed forest properties, and $318.00 per roll number for all other property classes, with a $10 discount when you e-file. Residential appeals are generally heard by summary proceeding. Do not confuse this with British Columbia's system: BC has its own assessor, its own January 31 review-panel deadline, and its own appeal board — none of those dates or bodies apply in Ontario.

Mistakes that waste an Ontario appeal

The most common mistake is missing the date on the notice — filing late ends the challenge before it starts. The second is skipping the RfR for a residential property and going straight to the Board, which the Board will not accept. The third is arguing current market value instead of the January 1, 2016 value and comparable assessed values. And the fourth is filing with no evidence: MPAC requires sufficient property-specific reasons and supporting documentation with every RfR, so gather the comparables and the photos before you submit, not after.

Figures the official pages do not state

MPAC's own pages state the RfR deadline only as "the date on your notice," so the March 31 annual-notice date and the 120-day period for other notices in this guide come from municipal and professional summaries of MPAC's process, not from a live MPAC page — your notice is authoritative. The Assessment Review Board's fee page on the Board's own site could not be verified, so the $132.50 and $318.00 fees are the Board's published filing fees as reproduced on the Board's own appeal form; confirm the current fee on the Board's site before you file.

Related guides

• How to start appealing your BC property assessment in Canada — the British Columbia companion: BC Assessment, the January 31 review panel, and the Property Assessment Appeal Board — a different assessor, different dates, different tribunal.
• First home purchase roadmap — what happens after the purchase: the assessment notice is one of the first official documents a new Ontario homeowner receives.
• GST/HST on rental and commercial property in Canada — the tax side of holding property: how GST/HST treats rental and commercial property differently from a principal residence.
• How to start a property management business in Canada — for owners with several properties: assessment challenges multiply across roll numbers, and each one carries its own fee and deadline.
• Richmond property taxes and utility bills — how the same assessment-into-tax-bill chain works in a BC city, for comparison with Ontario's MPAC system.

Sources

• Municipal Property Assessment Corporation, Request for Reconsideration and Appeals Fact Sheet — the RfR process, who must file one first, the 180-day response target, and the 90-day ARB appeal window.
• Municipal Property Assessment Corporation, Disagree with your assessment? — the RfR is free, residential owners must file one before appealing, and business properties may appeal directly.
• Municipal Property Assessment Corporation, Homeowners' Hub — AboutMyProperty registration, comparing your assessment with nearby properties, and filing the RfR online.
• Municipal Property Assessment Corporation, Property Assessment and Taxation toolkit: Key Messages — Ontario's January 1, 2016 valuation date and MPAC's role assessing more than 5.7 million properties.
• City of Windsor, Property Assessment — the 120-day RfR deadline from the notice issue date and the 90-day ARB window after MPAC's decision.
• Tribunals Ontario, Assessment Review Board — the Board's appeal process, forms, and filing fees.