If someone dies owning property in several provinces, which one issues the primary grant of probate?

Generally, the primary grant of probate is issued by the province where the deceased was domiciled — essentially, where they had their true, permanent home — at the time of death. That province's court is typically treated as having the main authority over the estate as a whole, while any other province where the deceased happened to own property deals separately with just that local property.

This matters practically because it shapes where the estate trustee starts: the application in the deceased's home province is usually the first and central one, and grants or recognitions obtained in other provinces are generally treated as secondary or "ancillary" to it, tied specifically to the property located there. Ontario's own process only ever governs Ontario's piece of that picture — it doesn't reach into another province's separate system.

Because domicile can occasionally be a genuinely disputed question (someone who split time between two places, for example), and because each additional province involved adds its own procedure and cost, an executor dealing with property in more than one province benefits from mapping out early which province is primary and coordinating counsel in each relevant location before starting any applications.