Should a professional corporation in Ontario be incorporated federally or provincially?

In practice, professional corporations in Ontario are almost always incorporated provincially under the Ontario Business Corporations Act rather than federally. There are good reasons for this.

Professional corporations must be approved by the relevant regulatory body in Ontario — the Law Society of Ontario for lawyers, the College of Physicians and Surgeons of Ontario for doctors, and so on. These bodies operate under Ontario legislation and administer their approval processes according to provincial rules. Many professional regulatory bodies only recognize professional corporations incorporated in Ontario for the purposes of professional practice.

A federally incorporated professional corporation would still need to register extra-provincially in Ontario and would need to meet all the same regulatory body requirements. The federal structure adds administrative complexity without providing any corresponding advantage for a practice that is, by its nature, tied to Ontario's regulatory framework and serving Ontario clients.

The exception might arise in rare cases where a professional corporation has activities genuinely spanning multiple provinces and needs the recognition a federal charter provides — but this is uncommon for most professional practices.