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Updated in March 2026
Understanding Ontario’s Property Assessment Appeal Process
Filing an Assessment Act appeal on time is an essential step in challenging the assessed value of your property or seeking other property tax relief. Ontario has a fairly complicated appeal system that we will help you understand.
When You Must File a Request for Reconsideration (RFR) with MPAC
If you want to appeal MPAC’s assessment of your property, you first need to know how the property is classified. If the property is in the residential, farm, or managed forest property class, you cannot appeal directly to the Assessment Review Board. Properties in those property classes must first file a Request for Reconsideration (RFR) with MPAC.
All other property types can file an appeal directly with the Assessment Review Board (ARB) by March 31 of the tax year, including industrial and multi-residential properties. However, any property owner may choose to file a request for reconsideration first as an opportunity to convince MPAC that the assessment should be corrected.
Deadline to File a Request for Reconsideration
A request for reconsideration must generally be filed with MPAC by March 31 of the tax year. There are some exceptions to this deadline, so you should always check the deadline listed on your Notice of Assessment.
Once the request is filed, MPAC has 180 days to respond. MPAC may extend that time to 240 days if they notify you before the 180-day deadline expires.
Deadlines to Appeal to the Assessment Review Board
If you have filed a request for reconsideration, the Assessment Act sets two potential filing deadlines for an appeal to the Assessment Review Board.
Appeal after MPAC issues a decision
First, if MPAC sends you a response that you disagree with, you must appeal within 90 days after the date printed on MPAC’s response.
Appeal if MPAC does not respond
If you do not receive a response from MPAC, your deadline is 90 days after MPAC should have responded. The Board refers to this as the “ultimate filing deadline.”
This deadline occurs 270 days after you filed the request for reconsideration, so it is important to track this date carefully.
Direct Appeals Without a Request for Reconsideration
If you are not required to file a request for reconsideration and choose not to do so, the filing deadline to appeal to the Board is March 31 of the tax year.
Getting Help With Property Tax Appeals in Ontario
Assessment Act appeals have a complicated series of filing deadlines.
NextGenLaw LLP has the expertise to help you navigate that web of rules. Contact us with your assessment concerns.
