In short: An Ontario Medical Professional Corporation pays roughly 11.2% combined tax (9% federal plus 2.2% provincial) on small business income, compared with a top personal rate of about 53.53%, and requires a Certificate of Authorization from the CPSO. This guide from ZAI Wealth Management explains deferral, salary versus dividends, Ontario Employer Health Tax and the passive income clawback.
Why incorporate in Ontario
Practising medicine in Ontario comes with rising overhead, OHIP billing and a fee schedule you don't control. A Medical Professional Corporation (MPC) is the most effective legal tool you have for keeping more of what you earn, once it's set up and run well.
To practise through a corporation, you need a permit from the College of Physicians and Surgeons of Ontario (CPSO).
The power of tax deferral in Ontario
Income you earn personally at the top bracket in Ontario is taxed at a combined rate of about 53.53%. Inside your MPC, active business income up to the small business limit is taxed at about 11.2% (9% federal + 2.2% provincial). Ontario cut its small business rate from 3.2% to 2.2% on July 1, 2026, so 2026 tax years straddling that date use a blended rate.
| Where the dollar is taxed | ON rate (approx.) | Left to invest |
|---|---|---|
| Top personal bracket | 53.53% | 46.5¢ |
| Your MPC (small business rate) | 11.2% | 88.8¢ |
That's roughly 42 cents more of every surplus dollar invested and compounding for you. It's a deferral, not a permanent saving: personal tax is paid when money comes out later. The advantage is the extra money growing in the meantime, often for decades.
Run your own numbers with our Physician Tax Savings Calculator.
Salary vs. dividends for Ontario physicians
- T4 salary: deductible to the corporation, builds RRSP room and CPP, supports mortgage approval, and is required for an Individual Pension Plan (IPP).
- Dividends: no payroll or CPP contributions and flexible timing, with a dividend tax credit on the personal side. They don't create RRSP room.
- The blended approach: most incorporated physicians take enough salary to build RRSP room (or fund an IPP), then top up with dividends. Review the mix every year.
Ontario Employer Health Tax: eligible private employers get an annual EHT exemption, but associated corporations share it. A larger corporate group can end up paying EHT on payroll.
Protecting your ON small business rate from the passive income clawback
If your MPC earns more than $50,000 of passive investment income in a year, your federal $500,000 small business limit shrinks by $5 for every $1 over. At $150,000 it's gone, and your practice income is taxed at Ontario's general corporate rate of about 26.5%.
Ways physicians stay under the line include tax-efficient corporate investing (growth over annual income), an Individual Pension Plan and corporately owned exempt policies. See our full guide to avoiding the passive income clawback.
Take control of your practice's surplus
Your practice isn't generic, and your corporate plan shouldn't be either. Start with our Physician Tax Savings Calculator, then book a call to go through your real numbers. For the bigger picture, read our physician tax strategy guide.
For illustration and general information only. Tax rules change and every situation is different, so speak with your advisor and accountant before acting on anything here.
Common questions
What is the corporate tax rate for a medical corporation in each province?
Combined small business rates for a Medical Professional Corporation are roughly 10% in Saskatchewan, 11% in Alberta, 11% in British Columbia, 11.2% in Ontario, 10.5% in Nova Scotia and 11% in Newfoundland & Labrador, each being the 9% federal rate plus the provincial rate. Top personal rates range from about 47.5% in Saskatchewan to about 54.8% in Newfoundland & Labrador. ZAI Wealth Management publishes a guide for each province on zaiwealth.ca.
Should a physician pay themselves salary or dividends?
Most incorporated physicians use a blend. A T4 salary creates RRSP contribution room, builds CPP entitlement, supports a mortgage application and makes an Individual Pension Plan possible; dividends are more flexible, avoid payroll administration and can be timed around income. ZAI Wealth Management sets the mix each year with the physician's accountant based on cash needs, registered room and retirement timeline.