The Date Debate: A New Battleground In Assessment Appeals

On May 15, 2025, the Ontario provincial government released its 2025 budget, and with it came no signs of a general reassessment of property taxes. For the foreseeable future, property tax assessments in Ontario will continue to be based on a January 1, 2016 valuation date. That said, after nearly a decade and counting with the same valuation date, a decision from the Assessment Review Board ("ARB") is sparking debate about how many valuation dates there are in Ontario's property tax assessment system.

In General Motors of Canada Company v Municipal Property Assessment Corporation Region 23, 2024 CanLII 55068 (ON ARB) ("General Motors"), the ARB interpreted the Assessment Act, S.O. 1990 C. A.31 (the "Act") as prescribing different valuation dates for omitted and supplementary assessments made during the assessment cycle. If not overturned, this interpretation may cause significant increases in tax liabilities for Ontario taxpayers.