Three layers, and only one of them is tax
The differences between your professional corporation and your neighbour's numbered company come in three layers, and confusing them is where most bad advice starts. The first layer is corporate law: Ontario's Business Corporations Act allows regulated professionals to incorporate their practices, but on conditions, restricted names, restricted activities, restricted shareholders. The second layer is your college: no professional corporation practises without its authorization, and the college's rules follow the corporation for life. The third layer is tax, where the surprise runs the other way, because the PC is taxed exactly like any other Canadian-controlled private corporation, with one nasty exception buried in the income-splitting rules.
That framing answers the reader's question directly: what you do differently is mostly administrative and structural, not tax-rate arithmetic. You file the same T2, claim the same small-business deduction and defer tax the same way an ordinary owner does. What you cannot do is copy an ordinary owner's structure, their holding company, their family share plan, their side ventures inside the same corporation, because the first two layers forbid it.
The facts that change what this means for you, worth naming before anything else:
- Your profession, because physicians and dentists get family-shareholder room that psychologists, physiotherapists, psychotherapists and most others do not.
- Whether your services are HST-exempt, which decides whether HST is a filing obligation or a hidden cost.
- How much profit you leave in the corporation, because deferral is the entire financial case and it only exists for retained profit.
- Your family's involvement, since TOSI decides whether family ownership means anything after tax.
- Whether your practice is saleable, because that determines if the lifetime capital gains exemption is worth protecting.
- What else you own or plan to own, real estate above all, because it shapes the structure beside the PC.
If you are still deciding whether to incorporate at all, the threshold math is profession-specific and lives on its own pages, for example should a psychologist incorporate in Ontario and should a physiotherapist incorporate in Ontario. This guide assumes the corporation exists and asks what running it well looks like.
Where your PC is just an ordinary corporation
Start with the reassurance, because it is most of the picture. A professional corporation is a Canadian-controlled private corporation: active practice profit up to the $500,000 small-business limit is taxed at roughly 12.2 percent combined in Ontario, profit above it at the general combined rate around 26.5 percent, and everything you have read about corporate tax deferral applies without modification. Leave a dollar of profit inside and you invest roughly 88 cents instead of the half-dollar a top-rate personal earner keeps; that spread, compounding until you draw it, is the whole engine.
The compliance machinery is ordinary too. The PC files a T2 within six months of its year-end and pays within the corporate deadline, runs a payroll account if it pays salaries, files T4s and T5s for what it pays out, keeps instalments current, and maintains books the CRA can follow. It can pick any fiscal year-end, which is a small but genuinely useful planning lever for smoothing income between corporate and personal years.
Ordinary planning tools work inside it as well. The salary-versus-dividends blend is the same annual calculation every owner-manager runs: salary buys RRSP room and CPP at the cost of payroll mechanics, dividends skip both, and the right mix follows your cash need, your registered-room strategy and the corporation's position against the small-business limit. Individual pension plans work. The capital dividend account works, crediting the untaxed half of corporate capital gains for tax-free extraction later. Corporate-owned life insurance works. None of these care that a college regulates you.
The passive-income rules are also profession-blind. Investment income inside any CCPC is taxed at roughly half on the way through, partly refundable when dividends are eventually paid, and once it passes $50,000 a year it grinds the federal small-business limit away, five dollars per extra dollar, gone at $150,000. Ontario declined to mirror the grind, softening it for Ontario professionals. A PC that retains seriously, and most successful ones do, needs a written surplus policy for the same reasons any investment-heavy corporation does.
The college layer: authorization, name and the permitted-business boundary
Nothing in the tax file matters if the college layer fails, because a professional corporation only exists as a practice vehicle while its certificate of authorization is valid. The college issues it, the college renews it, and the college must approve or be notified of changes that ordinary corporations make freely, new shareholders, name changes, sometimes amalgamations. Treat the college calendar with the same seriousness as the CRA calendar; a lapsed certificate is a practising-without-authorization problem, which is a professional discipline matter rather than a late-filing matter.
The name is prescribed, not chosen. Each profession's format requires the member's name and a required phrase identifying the profession and the words Professional Corporation, which is why no PC operates under a brand name directly; branding happens at the clinic level, through business names and, where structures grow, separate entities. Banks, insurers and billing systems must all hold the exact authorized name, and mismatches surface at the worst moments, in financings and in claims.
The permitted-business boundary is the least understood rule. A professional corporation may practise the profession and do what is related or ancillary to it, including temporarily investing its surplus funds; it may not run an unrelated business. Holding a portfolio is fine. Running a rental empire, a product company or a consulting arm unrelated to the profession inside the PC is not, and the fix is always the same: put the other activity in an ordinary corporation beside the PC. This boundary is also why clinic real estate almost never belongs inside a professional corporation, quite apart from the risk arguments.
One more thing the college layer does not do: protect you from malpractice. Professional liability follows the professional personally regardless of the corporation, which is what insurance is for. The corporation's protection is commercial, trade creditors, leases signed in its name, and the deferral engine above. We set these corporations up properly, name, articles, college filings, CRA accounts, as part of our incorporation service, and the setup is cheap compared to repairing an improvised one.
Who may own it: the table that decides most structures
Shareholder rules are where professions genuinely diverge, and they decide which planning conversations are even worth having. The pattern in Ontario is a two-track system: physicians and dentists received a family carve-out, and most other regulated professions did not.
| Profession group | Voting shares | Non-voting shares | Directors and officers |
|---|---|---|---|
| Physicians and dentists | Members of the profession only | Spouse, children and parents may hold; a trust may hold for minor children | Must be shareholding members |
| Most other regulated health professions (psychologists, physiotherapists, psychotherapists and others) | Members of the profession only | Members only, no family shareholders | Must be shareholding members |
| Lawyers, accountants and most non-health professions | Members of the profession only | Members only, subject to each regulator's rules | Must be shareholding members |
Three consequences fall straight out of that table. First, no holding company ever holds professional corporation shares, in any profession, so the standard opco-holdco structure, with surplus moving up as tax-free intercorporate dividends, is unavailable; the PC retains and invests its own surplus or pays it out with personal tax. Second, for members-only professions the corporation is a deferral vehicle, full stop, and any pitch built on family ownership should be shown the door. Third, even for physicians and dentists, family shares are an option to use carefully, because owning shares and benefiting from them after tax are different questions.
That difference is TOSI, the tax on split income, and it contains the one place tax law singles professional corporations out. Dividends to family members who do not really work in the business are taxed at the top personal rate unless an exception applies, and the most useful exception for ordinary businesses, holding at least 10 percent of votes and value of a company earning mostly non-service income, is defined to exclude professional corporations entirely. What survives: reasonable salaries for genuine work, dividends to family who average twenty or more hours a week in the practice, and spousal dividends once the professional is 65. Dentists and physicians planning around family shares should read the profession-specific treatment, for example our dentist tax planning page, before papering anything.
Succession and estate planning inherit the same constraints. Shares that only members may hold cannot simply pass to a spouse under a will and stay there indefinitely, colleges and the rules give estates limited room, so the corporation's death plan, insurance funding, and post-mortem tax strategy need to be designed within professional-ownership limits. It is solvable with time, awkward without it, and it belongs in the same file as your will.
The planning that still works, and the pitches to refuse
Inside those boundaries, a well-run professional corporation still supports serious planning. The reliable list: an annually recalculated salary-dividend blend; income smoothing across strong and weak years through corporate retention; RRSP and TFSA first, then corporate surplus as the overflow account; an individual pension plan for high earners past their early forties; capital dividend account extraction of the untaxed half of gains; and, for saleable practices, keeping the corporation clean for the $1.25 million lifetime capital gains exemption. Every one of those is orthodox, defensible and quietly valuable.
The exemption point deserves its own sentence, because professions split on it. A dentist, veterinarian or other professional whose practice sells as a going concern should treat qualifying-small-business status as an asset, passing the active-asset tests at sale and through the prior twenty-four months, which heavy corporate portfolios can spoil. A professional whose goodwill is personal, most solo physicians and many therapists, will likely never sell shares, and for them the exemption argument for any structure is close to worthless. Knowing which kind of practice you own changes what your surplus policy protects.
Now the refusals. Refuse any structure that puts a holding company over a professional corporation, in Ontario it is simply not available. Refuse family-dividend plans that never mention TOSI by name. Refuse arrangements that move practice income into entities with no real function, because the general anti-avoidance rule and the reasonableness tests exist precisely for fee structures without substance. And be properly skeptical of insurance-led planning where the tax story arrives before the insurance need; the good versions survive being modelled against the boring alternative, and the bad ones do not.
The test for any proposal is boring and reliable: what does it do after tax, after costs, after TOSI, in your profession's shareholder rules, compared to simply retaining and investing inside the PC? A proposal that cannot answer on those terms is not planning; it is a product.
Running it well: books, HST and the structure beside the PC
Day to day, a professional corporation runs on the same discipline as any good owner-managed company: a corporate account with an absolute wall against personal spending, monthly books, receivables that someone works, instalments projected from this year rather than copied from last, and a minute book that matches the share register. The professional overlay adds the college calendar and, for regulated health services, an HST profile that needs actual thought.
HST for professionals splits by what you sell. Exempt clinical services mean no HST charged and none recovered, so HST becomes a hidden cost in rent, equipment and supplies; taxable streams, reports for insurers and lawyers, some assessments, cosmetic services, consulting, directorships, count toward the $30,000 small-supplier threshold and, past it, force registration and a clean split of the books between exempt and taxable activity. The exemption list itself moves over time, psychotherapy services became exempt recently, so the classification deserves a periodic review rather than a permanent assumption.
Multi-entity structure, where it belongs at all, sits beside the PC rather than above it. An ordinary corporation can own the clinic premises and lease them to the PC at market rent; a service corporation can hold equipment and employ non-clinical staff, with more shareholder freedom because it is not a professional corporation; and each added entity costs a T2, separate books and unrecoverable HST on intercorporate charges where the PC's revenue is exempt. The structures earn their keep when there is real property, genuine risk separation or a real sale coming, and reorganizing into them is defined-scope work we run as Strategic Projects, papered so any asset moves are tax-deferred where the rules allow.
If you searched for a CPA for incorporated healthcare professionals in Ontario, the honest job description is exactly this page: keep the three layers, college, corporate, tax, agreeing with each other, and put the planning inside the boundaries your profession actually has. That is standing work, not seasonal work, which is why our professional clients mostly sit on an ongoing engagement with defined projects for the structural moments. A free 15-minute discovery call is the first step, and the first meeting's output is a list: what your PC is doing that an ordinary corporation could not, and what it is failing to do that any corporation should.
