Does someone facing a capacity assessment have the right to be told about it in advance in Ontario?

Yes, generally. A person facing a capacity assessment under the Substitute Decisions Act is entitled to be told, in advance, that an assessment is being proposed, what it involves, and, importantly, that they generally have the right to refuse to participate. This is meant to respect the person's autonomy and make sure the process isn't something done to them without their knowledge, even where family members or others have raised the concern that led to the assessment being proposed.

Because a capacity assessment can lead to significant legal consequences — including a statutory guardianship of property — advance notice and an explanation of the person's rights are treated as an important safeguard, not a mere formality. If you're arranging a capacity assessment for a family member, make sure the assessor's process includes this notice properly, and if you're the person facing an assessment and weren't given this information beforehand, or feel pressured rather than informed, raise that concern directly, since it can affect how much weight the resulting assessment carries later. A lawyer can help clarify what notice and rights should have been provided in your specific situation.