Sole Proprietorship vs. Incorporation in Ontario: The Real Tax Math

"Should I incorporate?" might be the most-asked question in Canadian small business, and most answers are either "yes, immediately" from someone selling incorporations or "it depends" with no actual numbers. Let us do better. Here is how each structure is actually taxed in Ontario in 2026, a worked example with real dollars, what it costs, and a checklist you can use today.

How is a sole proprietorship taxed in Ontario?

A sole proprietorship is you. There is no separate legal entity. Every dollar of business profit lands on your personal T1 return in the year you earn it and gets taxed at your personal marginal rates, the same brackets that apply to a salary. Earn more, and each additional dollar is taxed at a higher rate.

The mechanics are simple, which is the structure's biggest selling point:

• You report business income and expenses on your T1 (via form T2125). No separate corporate return.
• Your filing deadline is June 15 as a self-employed person, but any balance owing is still due April 30.
• You can still deduct legitimate business expenses. The write-off rules are largely the same as for corporations.
• Once revenue passes $30,000 over four consecutive quarters, you must register for HST, incorporated or not.

One cost that surprises people: sole proprietors pay both halves of CPP. An employee pays 5.95% and their employer matches it. When you are self-employed, you are both, so you pay 11.9% on net self-employment income between the $3,500 exemption and the $74,600 ceiling in 2026. At the maximum, that is roughly $8,460 per year on top of income tax.

How is a corporation taxed?

A corporation is a separate taxpayer. It earns the profit, files its own T2 corporate return, and pays its own tax. And as of July 1, 2026, that tax got cheaper: Ontario cut its small business rate from 3.2% to 2.2%, so a Canadian-controlled private corporation now pays a combined 11.2% (9% federal plus 2.2% Ontario) on its first $500,000 of active business income.

Here is the part the "incorporate and pay 11.2%!" pitch skips: that rate applies to money that stays in the corporation. The moment you pay yourself, a second layer of tax kicks in:

• Salary is deductible to the corporation, but taxed in your hands at personal rates, with CPP on both sides.
• Dividends come out of after-tax corporate profit and are taxed personally at dividend rates designed to roughly account for the corporate tax already paid.

The tax system is built so that a dollar earned and fully paid out to you ends up taxed at roughly the same total rate either way. If you need every dollar the business makes to live on, incorporation is not a tax play. Its power shows up only when money stays behind.

What is the deferral advantage, in real dollars?

This is the whole ballgame, so let us work an example.

Say your business earns $150,000 of profit and you need $80,000 to live on.

As a sole proprietor: all $150,000 is taxed on your personal return this year, at marginal rates that climb well past 40% at that income level, whether you spent the money or not. The $70,000 you did not need still gets taxed as if you did.

As a corporation: you pay yourself an $80,000 salary, which the corporation deducts. That salary is taxed personally, similar to the sole proprietor's first $80,000. But the remaining $70,000 stays in the company and is taxed at just 11.2%, about $7,840, leaving roughly $62,160 working inside the corporation.

Compare the treatment of that same $70,000: if it were taxed personally at a marginal rate above 40%, the bill would top $28,000. Inside the corporation, it is $7,840. That difference, usually $20,000 or more in this scenario, is not permanently saved. You will pay personal tax when you eventually take the money out. But until then, it is capital you can use to hire, buy equipment, build a cash cushion, or invest. That is the deferral advantage, and it compounds every year you leave profit behind.

Flip the example and the advantage vanishes: if you need all $150,000 to live on, everything flows to you and gets taxed personally either way, and you have added corporate filings and accounting fees for roughly nothing.

What about liability protection?

Tax is only half the decision. A corporation is a separate legal person, so business debts and lawsuits generally stop at the corporation instead of reaching your house and savings. That matters more in some businesses than others: contractors, anyone signing leases or supplier contracts, businesses with employees, or work where something going wrong gets expensive.

Two honest caveats. Banks routinely ask small business owners for personal guarantees, which pierce that protection for the debts that matter most. And no corporation shields you from your own professional negligence, which is what insurance is for. Liability protection is real, but it is a reason to incorporate alongside the tax math, rarely instead of it.

How much does it cost to incorporate in Ontario?

Less than most people think up front, more than most people think ongoing:

The ongoing line is the one that matters. A corporation must file a T2 every year, even with no activity, and needs proper books and financial statements behind it. Realistically, incorporating adds a few thousand dollars a year in professional costs, so the tax deferral needs to beat that before incorporation nets out positive.

When does incorporating start making sense?

There is no magic revenue number, because the trigger is not revenue. It is profit you can leave in the company. As a rough rule for Ontario in 2026:

• Retaining $30,000+ per year? The deferral usually outruns the added costs comfortably. This often happens once profit clears $100,000 to $150,000 and your personal spending does not rise with it.
• Spending everything you earn? Stay a sole proprietor for now, unless liability or a specific contract pushes you the other way. Revisit annually.
• Non-tax triggers: clients that only contract with corporations, bringing on a partner or investor, building something you may sell one day, or meaningful liability exposure.

Here is the side-by-side:

What should you do next?

If you are close to the line, the decision deserves an hour with real numbers: your actual profit, your actual living costs, and your plans for the next three years. A good advisor will also flag the details this guide left at a high level, like the salary-versus-dividend mix and the right share structure, which are covered in our guide to choosing a small business accountant in Toronto.

Already incorporated or about to be? Get ahead of the filing side with our T2 corporate tax guide. And if you want a straight answer on your own situation, take the free assessment. It takes five minutes and does the math on your numbers, not a hypothetical.