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Incorporating an engineering firm: an ordinary corporation plus the PEO certificate
Ontario has no special professional corporation for engineers — the standard structure is an ordinary corporation holding a Certificate of Authorization from PEO, and the firm cannot offer engineering services to the public until that certificate is in place. The split to understand before you file anything: the licence and the responsibility for sealed work stay with the P.Eng personally, while the contracts, the work in progress, and the tax advantages sit in the company.
By the AnalytIQ Accounting team · Last reviewed: August 12, 2026
The Certificate of Authorization belongs to the firm
Any entity that offers or provides professional engineering services to the public in Ontario needs a Certificate of Authorization from Professional Engineers Ontario — sole proprietorships and partnerships included, but for a growing consultancy the corporation is the natural holder. The certificate names the professional engineer or engineers who assume responsibility for and supervise the firm's engineering work, and its conditions and process are PEO's to set and to change, so confirm the current requirements directly with PEO before you commit to a launch date. The working order is simple: incorporate, apply, and only then put the firm's name on a proposal.
Professional corporation or ordinary corporation?
This is the question engineers ask us most, and the answer surprises them: the OBCA's professional-corporation regime covers listed professions like medicine, law, and accounting, while engineering runs on its own track through the Professional Engineers Act and the Certificate of Authorization. A typical consulting firm is an ordinary Ontario or federal corporation that holds a C of A — no Professional Corporation suffix, no separate PC application.
That difference has a practical payoff. Share structure is far more flexible than in a physician or lawyer PC: partners, a holding company, and in many cases family members can hold shares, subject to PEO's requirements about who directs and supervises the engineering — verify the current rules for your ownership plan. Flexibility is not a tax loophole, though. The TOSI rules still tax most family dividends from a services firm at top personal rates, so build the case on deferral and structure, not on splitting.
Who holds what once the firm is authorized
| Item | Where it sits | Notes |
|---|---|---|
| P.Eng licence | The engineer, personally | Discipline and the seal never move to the company |
| Certificate of Authorization | The corporation | Names the P.Eng(s) responsible for the engineering |
| Responsibility for sealed work | The engineer, with the firm alongside | Professional liability insurance responds first |
| Insurance or client disclosure | The firm | PEO expects coverage or written disclosure to clients — confirm current rules |
| Client contracts, subconsultants, WIP | The corporation | Commercial disputes stop at the company |
| HST collected and source deductions | Directors, personally | Trust amounts pierce every structure |
Where the corporation earns its keep financially
Consulting engineering runs on long money cycles — proposals written for free, milestones billed months apart, holdbacks on construction-adjacent work — and retained corporate profit taxed at roughly 12.2% on the first $500,000 is the cheapest working capital a firm can hold. It carries payroll through the gap between invoice and payment and funds the hires that let you bid the next tier of projects. The alternative — drawing everything out at personal rates above 50% and lending it back when the firm runs short — burns nearly forty points of tax for no reason.
The corporation also cleans up how the principals get paid. Draws become a deliberate salary and dividend mix set once a year with the T2 in view, rather than transfers timed to whichever milestone just cleared, and the firm's HST registration from day one recovers the tax on software seats, testing equipment, and subconsultant invoices that a consultancy accumulates quickly.
Two more levers are specific to engineering. Firms doing genuine experimental development can access SR&ED credits, and a Canadian-controlled private corporation gets the enhanced refundable rate — the claim itself lives naturally inside a corporation. And a one-person consultancy embedded in a single client's team should read our page on incorporating as an IT consultant before celebrating the tax rate: the personal services business rules apply to solo engineers exactly the same way.
Names, sequence, and the switch
The Professional Engineers Act restricts who may use engineer and engineering in a business name, so clear your proposed name against PEO's rules before paying for a NUANS search that leads nowhere. From there the cutover is deliberate: articles, C of A, bank account, insurance in the corporate name, then new engagements papered to the company — existing multi-year assignments move only with client consent, so switch between projects. Firms billing US clients face W-8BEN-E requests and state-level questions the moment site work crosses the border; that layer lives on our cross-border tax page for engineering firms. For the corporate file end to end, see our incorporation and compliance service.
Source: Professional Engineers Ontario.
Common questions.
Do engineers form professional corporations in Ontario?
Generally no — engineering is not on the OBCA professional-corporation list. The standard structure is an ordinary corporation that holds a PEO Certificate of Authorization, which also means more flexible shareholding than a physician or lawyer PC, subject to PEO's rules.
Does the corporation protect the engineer who sealed the drawings?
No. Responsibility for sealed work stays with the P.Eng personally, and PEO expects the firm to carry professional liability insurance or disclose to clients in writing that it does not. The corporation contains commercial exposure — contracts, leases, payroll, and financing.
When in the process do we apply for the Certificate of Authorization?
After incorporation and before offering any engineering services to the public. The certificate is issued to the entity and names the responsible P.Eng(s), so the corporation must exist first — build PEO's processing time into your launch plan.
Related reading
Authorize the firm, then build it.
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