Introduction
For licensed professionals in Ontario — doctors, dentists, lawyers, accountants, optometrists, veterinarians, architects, engineers, and others — incorporation is permitted, but the structure is meaningfully different from an ordinary Ontario business corporation. The corporation must satisfy not just the Business Corporations Act (Ontario) but also the governing professional statute and the specific rules of that profession’s regulator on naming, ownership, and conduct. Getting the structure right unlocks real tax planning. Getting it wrong creates regulatory exposure on top of ordinary corporate exposure.
A professional corporation in Ontario is a corporation incorporated under the OBCA and authorized by the professional’s regulator to provide a specific professional service, such as medicine, dentistry, or law. Its shares generally must be owned by members of that same profession, and incorporation itself provides no shield against personal liability for professional negligence.
This guide explains how a professional corporation actually works in Ontario in 2026 — who can incorporate, what the share-ownership rules are, what changes about liability, and where the real tax advantages come from.
What Is a Professional Corporation in Ontario?
A professional corporation is an Ontario business corporation incorporated under the OBCA and authorized by the relevant regulator to provide professional services. The regulator issues a certificate of authorization confirming the corporation meets its requirements — and without that certificate, the corporation cannot lawfully provide the professional service, even though it has technically been incorporated.
The relevant regulators include the Law Society of Ontario for lawyers and paralegals, the College of Physicians and Surgeons of Ontario for physicians, the Royal College of Dental Surgeons of Ontario for dentists, and Chartered Professional Accountants of Ontario for CPAs. Optometrists, veterinarians, engineers, and architects are governed respectively by the College of Optometrists of Ontario, the College of Veterinarians of Ontario, Professional Engineers Ontario, and the Ontario Association of Architects, each with its own by-laws. Each regulator’s rules differ in the details, so the framework below describes the common shape — the specifics for any individual profession must be confirmed against that regulator’s current by-laws.
Who Can Own Shares in an Ontario Professional Corporation?
This is the rule that surprises new clients most: a professional corporation generally cannot have outside shareholders. The voting shares of an Ontario professional corporation must be owned by members of the same profession, and in most cases only that one profession’s members can hold voting shares.
Several professions allow family members to hold non-voting shares for income-splitting purposes, but the rules differ meaningfully between regulators. In medicine and dentistry, non-voting shares may be held by family-member shareholders — a spouse, parents, or children — under the regulator’s rules. In law, the Law Society’s by-laws restrict ownership to LSO licensees, and non-voting family shares are not permitted in the same way. Accountants and engineers are generally restricted to members of the profession as well.
Where the non-voting-family-share option is available, it forms the structural backbone of income-splitting planning for professional families — though the tax effectiveness of these plans has been significantly reduced by the federal Tax on Split Income (TOSI) rules in effect since 2018. Income splitting still works in some circumstances, but the easy versions are gone. Where multiple family members hold shares, even non-voting ones, a shareholder agreement becomes important to set out how those shares are valued and what happens if the professional’s circumstances change.
Naming Rules for a Professional Corporation
Professional corporations have specific naming requirements set by the regulator. As a general framework, the name must include the professional’s surname (and often initials or full name), the professional designation — “Medicine,” “Dentistry,” “Law,” “Optometry,” and so on — and the words “Professional Corporation,” rather than “Inc.” or “Ltd.”
Typical examples include “Smith Law Professional Corporation,” “Dr. J. Patel Medicine Professional Corporation,” “Lee Dentistry Professional Corporation,” and “Chen Accounting Professional Corporation.” Numbered professional corporations are generally not permitted, because the corporate name itself has to identify both the professional and the profession — unlike an ordinary Ontario business, where our guide to numbered vs. named corporations in Ontario explains that a numbered option is often available.
A practising professional can operate the practice under a different trade name — for example, “Mississauga Family Dental” — but the rules on trade-name use vary by regulator and have to be checked individually. The legal corporate name still appears on the certificate of authorization, on bills, and on all professional communications.
Liability: Why a Professional Corporation Doesn’t Shield Negligence Claims
The biggest misconception about professional corporations is that they protect the professional from negligence claims. They don’t. The professional remains personally liable for their own professional negligence regardless of the corporate structure, and most regulators reinforce this by requiring mandatory professional liability insurance — LawPRO for lawyers, the CMPA for physicians, and comparable schemes for other regulated professions.
What the corporate structure does protect against is non-professional liability: premises liability, contract disputes with suppliers, employment claims, and equipment leases. A landlord suing the practice for unpaid rent, a supplier suing over an unpaid invoice, or a former employee suing for wrongful dismissal are generally limited to pursuing the corporation’s assets rather than the professional’s personal assets, provided the corporation has been properly maintained as a separate legal entity. For most professionals, the personal-liability-for-negligence point is the headline takeaway — but the corporate shield remains real and valuable for everything else.
