What counts as a 'substantial renovation' that can trigger HST self-assessment on a rental property?

For GST/HST purposes, a "substantial renovation" generally means a renovation so extensive that all, or substantially all, of the existing building has been removed or replaced, leaving only elements like the foundation, external walls, interior supporting walls, floors, roof, and staircases from the original structure largely intact, in effect, treating the result as close to a newly built home rather than a repaired or updated older one. A more modest renovation, even an expensive one, generally doesn't meet this threshold just because a lot of money was spent.

Whether a project clears that bar matters because a substantial renovation is treated much like new construction: it can trigger the same self-supply and change-of-use consequences as building a brand-new home, including a potential HST self-assessment obligation if the renovated property is then used as a rental instead of being sold. A partial gut renovation that keeps significant original structure, by contrast, generally wouldn't reach that same treatment.

Because the line between a major renovation and a qualifying "substantial renovation" is a matter of degree and depends on exactly how much of the original structure survives, this is worth having assessed by an advisor against the specific scope of your project before assuming, either way, whether HST self-assessment applies.