The Professional Corporation Decision in Ontario (2026): Should Physicians and Dentists Incorporate?

Most advice on whether a physician or dentist should incorporate starts with the tax rates: a combined 11.2 percent on active business income within the small business limit, the fully phased-in rate after Ontario's July 1, 2026 cut, against personal rates of up to 53.53 percent in Ontario. That gap is real, but it applies only to income you leave in the corporation, and only until you take it out. For most professionals, incorporation is a way to defer tax, not avoid it. Whether it is worth doing depends on how much you can leave invested, for how long, and at what rate it eventually comes out.

This guide covers what a medicine or dentistry professional corporation is in Ontario, what it does and does not change, the 2026 numbers, and how to decide.

What a professional corporation is in Ontario

A professional corporation is an ordinary Ontario corporation, incorporated under the Business Corporations Act, that holds a certificate of authorization from your college: the College of Physicians and Surgeons of Ontario (CPSO) or the Royal College of Dental Surgeons of Ontario (RCDSO). Without the certificate, it cannot hold itself out as a health profession corporation. The rules are stricter than for other businesses:

• Ownership. Every voting share must be owned by a member of your college. Non-voting shares can be owned only by a member, by your spouse, child or parent, or by individuals holding them in trust for your minor children. A holding company or an ordinary family trust cannot be a shareholder.
• Directors and officers. All of them must be shareholders who are members of your college.
• Name. The name must include "Professional Corporation", the surname of a member shareholder as it appears on the college register (given names or initials may be added), and the profession, with nothing else. CPSO's example is "Smith Medicine Professional Corporation". Numbered names are not allowed.
• Business. The corporation may carry on only the practice of the profession, plus related or ancillary activities, which the Act says include investing the corporation's surplus funds. So it can build an investment portfolio from retained earnings, but it cannot run a separate business.
• Ongoing obligations. The certificate is renewed every year: CPSO charges $400 to apply and $175 to renew, and RCDSO charges $750 to apply and $175 to renew by July 31, with every dental certificate expiring on August 31. CPSO expects changes to the corporation's physician shareholders to be reported within 15 days, and a college can revoke the certificate if the corporation stops meeting the rules.

What incorporation does not do

Four common beliefs about incorporating do not hold for physicians and dentists.

It does not shield you from malpractice claims. The Act states that a member's liability for a professional liability claim is not affected by practising through a professional corporation, and makes member shareholders jointly and severally liable with the corporation for those claims. Non-voting shareholders who are not college members, such as a spouse or child, are exempt from that provision, so the distinction matters for family shareholders, but it never protects the practising professional. Your professional, fiduciary and ethical obligations to patients are unchanged. A corporation can limit some ordinary business liabilities, but your professional liability protection stays essential.

It does not make income splitting easy. Family members can hold non-voting shares, but dividends to them are subject to the tax on split income rules. The main exception for owners of other small businesses, "excluded shares", is never available for shares of a professional corporation. In most cases, dividends to a spouse are taxed at the top rate unless an exception applies, such as the one for spouses once the owner reaches 65. Some physicians and dentists incorporated years ago partly for income splitting that the 2018 rules have since limited.

It does not recover HST. Most medical and dental services are exempt supplies, so a professional corporation generally cannot claim input tax credits on the HST it pays on rent, equipment and supplies. Incorporating does not change that.

It does not turn personal spending into business expenses. Paying a personal expense through the corporation does not make it deductible. Depending on the circumstances, it may be compensation, a shareholder loan or a taxable shareholder benefit, and a benefit usually costs more than simply paying yourself.

The real benefit: deferral

When you practise unincorporated, all of your net professional income is taxed personally in the year you earn it, whether you spend it or not. Through a corporation, the corporation pays tax at the small business rate on the first $500,000 of active income, and you pay personal tax only on what you take out as salary or dividends. Money left in the corporation has paid only corporate tax, so there is more of it to invest.

Here is one year of 2026 income, run through the Incorporation Decision Calculator. Assumptions: $300,000 of net professional income after practice expenses, $150,000 of after-tax spending, 2026 federal and Ontario rates, the fully phased-in 11.2 percent small business rate, and no extra annual cost for the corporation. The corporation pays you a $2,000 salary with dividends for the rest, the lowest-tax mix for this spending.

The corporation leaves $34,819 more to invest this year. That uses the fully phased-in 11.2 percent rate. A corporation with a calendar 2026 taxation year pays a prorated rate of about 11.696 percent for 2026, because Ontario's cut took effect July 1, which reduces the figure to $33,346.

That figure is not a saving, and it is not the whole picture:

• The retained money is taxed when it comes out. If all $63,467 is later paid out as non-eligible dividends at 48.89 percent, the top rate from 2027 once Ontario's lower dividend tax credit applies, the advantage shrinks to about $3,790. Most of that is the CPP not paid, and CPP buys a pension: excluding CPP, the corporation comes out about $1,640 behind at that rate.
• The rate at payout decides the result. Using illustrative flat payout rates, not a forecast for any particular withdrawal, the calculator's two lower presets give different answers: at 37.90 percent the advantage after payout is about $10,800, and at 22.38 percent about $20,600. Those are 2026 marginal rates on non-eligible dividends in two lower brackets; the rate you actually pay depends on the year, the dividend gross-up and how your withdrawals fall across brackets, so model your own withdrawal plan with your accountant.
• Time adds value. The calculator is deliberately a one-year snapshot. The real benefit of deferral is that the extra money is invested for years before the tax is paid, although investment income inside the corporation is taxed at higher corporate rates, as covered in the corporate investing guide.
• RRSP room differs. The table includes no RRSP contributions. An unincorporated professional with room can shelter part of their $28,648 and deduct it, which narrows the gap. A corporation can recreate the room by paying salary: at a salary of $196,611, which creates the maximum 2027 RRSP room, the corporation still leaves $24,778 more to invest this year, with both sides having the same RRSP room. Given the same treatment as the example above, that route ends about $1,340 behind once the retained money is paid out at 48.89 percent, before any investment growth.

In short, incorporation mostly changes when you pay tax, and sometimes at what rate. The longer the money stays invested and the lower your income when it comes out, the more it is worth.

When incorporation tends to pay off, and when it does not

The deferral depends on the gap between what you earn and what you spend. Under the same assumptions, the extra left to invest in the first year is about $16,800 at $200,000 of income and $120,000 of spending, and about $51,500 at $400,000 and $180,000.

Incorporation tends to be worth more when:

• you earn well above what you spend, and expect to for years
• you can leave the surplus invested in the corporation rather than needing it personally, for example to pay down a mortgage or student debt faster
• you expect to draw on the corporation later at a lower income, such as in a gradual retirement or during parental leave
• you are a dentist who may eventually sell the practice through its shares, where the lifetime capital gains exemption, $1,275,000 for 2026, can apply if the shares qualify

It tends to be worth less when:

• you spend nearly all of your income, so there is little to defer and the running costs remain
• you need the money personally in the short term, since every dollar paid out pays the personal tax you deferred
• you are close to retiring and would draw the money out quickly
• your income is modest or irregular, such as in the first years after training

The costs matter at the margin. The college fees are small, but a corporation needs legal set-up, its own financial statements and a corporate tax return every year. As a hypothetical illustration, a $5,000 annual cost reduces the first-year advantage in the example from $34,819 to $30,379, and the advantage after payout at the top rate to about $1,500. Use your accountant's actual quote in the calculator.

What comes with a corporation

Incorporating opens a set of decisions you did not have before, each covered in its own guide.

• How to pay yourself. Salary, dividends or a mix, with different effects on RRSP room, CPP and tax. See salary vs dividends in Ontario and eligible vs non-eligible dividends.
• How to invest what you keep. Investment income over $50,000 a year, counting associated corporations, reduces the small business limit, which at the fully phased-in Ontario rates can mean up to $30,000 a year of extra corporate tax. See the corporate investing guide and the passive income calculator.
• Pensions. An individual pension plan is available only through salary from a corporation. See IPP vs RRSP for medical professionals.
• Insurance ownership. Life insurance owned by the corporation is paid with corporate dollars. When the corporation receives a death benefit, the proceeds less the policy's adjusted cost basis are generally added to its capital dividend account, and paying that out tax-free requires a capital dividend election. See the corporate-owned life insurance guide. Disclosure: I am a licensed insurance and investment advisor and life insurance is among the products I place, so have your accountant review any ownership structure.
• Payroll and employer health tax. If the corporation employs staff, it runs payroll. Ontario's employer health tax does not apply to the first $1 million of payroll, shared among associated employers, and the exemption is generally lost once the associated group's Ontario payroll exceeds $5 million.
• Association. Corporations controlled by the same people, and in some cases corporations owned by related people, depending on who controls them, can be associated and must share one $500,000 small business limit. Have your accountant check this before setting up a second corporation.

Setting it up

The usual sequence, which your lawyer and accountant coordinate, is:

1. Incorporate under the Ontario Business Corporations Act, with articles that meet the professional corporation rules and the college's naming format.
2. Apply for the certificate of authorization from CPSO or RCDSO before the corporation practises.
3. Redirect income. Physicians register with the Ministry of Health so OHIP payments can be made to the corporation through group registration, using form ON00574 with at least 60 days' notice of changes. Clinic, hospital and private-pay arrangements need to be moved to the corporation's name as well.
4. Open corporate accounts and keep corporate and personal money separate from day one.
5. Review contracts, insurance and benefits, including who owns and pays for disability, life and overhead insurance, since ownership affects both tax and claims.
6. Plan the first year's pay: how much you need personally, whether to create RRSP room, and what the corporation will do with the rest.

How to decide

Start with three numbers: your net professional income, what you need to spend, and your accountant's quote for the annual cost of a corporation. Run them through the calculator above, and look at both results, what the corporation leaves to invest this year and what remains once that money is taxed on the way out. Then ask how long you expect to leave the difference invested and what your income is likely to be when you draw on it.

If the gap between earning and spending is large and lasting, incorporation usually earns its keep. If it is small, or you will need the money soon, staying unincorporated can be simpler and costs little. How incorporation fits with the rest of a plan is covered on the pages for physicians and dentists.