Occupational therapist incorporation: what a COTO corporation changes

What a professional corporation actually changes

COTO issues a certificate of authorization that lets a registered occupational therapist bill their own treatment and assessment work through a professional corporation rather than personally, moving that income from a T1 to a T2. The main draw is the lower small-business corporate tax rate on income retained inside the corporation rather than paid out — useful for an OT building up capital for equipment, a second location, or a slower season, less useful for one who needs most of the billings as personal income every year regardless of the tax rate on the way through. Retained earnings do come with a limit: a corporation that builds up enough passive investment income can see its own access to the small business rate ground down in later years, which is a reason to plan withdrawals rather than let cash simply accumulate by default. The certificate of authorization itself is not a one-time approval — it is typically renewed annually alongside the corporation's own annual return, and a lapse in COTO registration or in the certificate can put the corporation's eligibility to bill as a professional corporation in question, which is worth building into whoever's calendar tracks corporate compliance.

Who can hold shares

Voting shares in an OT professional corporation generally have to be held by the OT themselves, consistent with the regulated-profession ownership rules under Ontario's Health Profession Corporation framework. Some colleges allow limited non-voting participation by family members through specific share classes, and the rules vary by college and can change, so this is worth confirming against COTO's current requirements before assuming a spouse or family trust can hold any part of the corporation. Even where a non-voting class is available, income sprinkled to a family member who does no real work in the practice is squarely within the tax-on-split-income rules, so a share structure has to be paired with an actual role before it changes anyone's tax bill.

Incorporation does not touch your liability exposure

A corporation shields its shareholder from the corporation's ordinary business debts — a lease default, a supplier invoice, an employee claim — but it does not shield a therapist from personal liability for their own professional negligence. Professional liability insurance stays essential at exactly the same level after incorporation as before it, and lenders and landlords routinely ask for a personal guarantee from a small professional corporation regardless of the corporate shield on paper. Owners sometimes discover this the first time they lease an office or finance equipment through the new corporation and are asked to co-sign personally anyway.

Updating payers to bill the corporation, not you

Incorporation is not just a filing change — SABS insurers, WSIB, and any extended-health direct-billing relationships need to be updated to invoice and pay the professional corporation rather than the OT personally, and the HCAI provider profile behind auto-insurer claims needs the same update. A practice that incorporates but keeps invoicing insurers under the old personal registration ends up with income landing in the wrong entity, which is a harder problem to unwind at year-end than it is to set up correctly on day one. GST/HST registration usually needs its own new business number for the corporation as well, rather than simply continuing to file under the sole proprietor's old number, since the corporation is a separate legal person from the OT who owned the practice before it.

Timing incorporation around your payer mix

A practice heavy in SABS and WSIB receivables collects slowly enough that the calendar year and the cash-collection year can drift meaningfully apart, which matters for a first corporate year-end and for instalment planning. We usually recommend choosing a fiscal year-end and an incorporation date that line up with a practice's actual collection pattern rather than the calendar, so the first T2 is not built on estimates of cash the practice has not seen yet. A practice that incorporates mid-year, in particular, should model its first short fiscal period on receivables it can actually see, not on a straight pro-rated slice of the prior year's revenue.

For the day-to-day filing questions once the corporation exists, see our OT tax services page; for US-trained OTs weighing a return to Canada, see our OT cross-border tax page.