Ontario Small Business Deduction 2025: Rates, Eligibility, and Planning Strategies

The small business deduction (SBD) is the single most important tax benefit available to Canadian-Controlled Private Corporations (CCPCs) in Ontario. It reduces the corporate tax rate on active business income from the general corporate rate down to a significantly lower small business rate — creating powerful tax deferral opportunities for business owners.

The 2025 Small Business Tax Rates in Ontario

In Ontario, a CCPC claiming the full small business deduction pays a combined federal and provincial corporate tax rate of approximately 12.2% on active business income up to the $500,000 business limit.

Above the $500,000 business limit, income is taxed at the general corporate rate of approximately 26.5% combined. This creates a significant incentive to manage corporate income carefully.

• Small business rate (Ontario): ~12.2% combined (9% federal + 3.2% Ontario)
• General corporate rate (Ontario): ~26.5% combined
• Tax deferral advantage vs top personal rate (53.5%): up to 41.3%
• $500,000 business limit applies per associated group of corporations

What Is a CCPC and Do You Qualify?

A Canadian-Controlled Private Corporation (CCPC) is a private corporation that is resident in Canada and NOT controlled by non-residents or public corporations.

Most small business corporations owned by Canadian residents qualify automatically. The key requirements are: incorporated in Canada, not listed on a stock exchange, and controlled by Canadian residents.

• Must be a private corporation (not publicly traded)
• Must be Canadian-controlled (majority of votes held by Canadian residents)
• Must be resident in Canada
• Cannot be controlled by a non-resident or public corporation

The Passive Income Grind-Down Rule

Since 2019, CCPCs with significant investment income face a reduction in their $500,000 business limit — called the passive income grind-down. This was introduced to discourage using corporations as investment vehicles.

For every $1 of adjusted aggregate investment income (AAII) over $50,000, the business limit is reduced by $5. The limit is fully eliminated at $150,000 of passive income.

• Business limit reduced $5 for every $1 of passive income over $50,000
• Full $500,000 business limit available if passive income is under $50,000
• Business limit fully eliminated at $150,000 of annual passive income
• Passive income includes: interest, rental income, taxable capital gains, dividends

The Associated Corporations Rule

If you own or control multiple corporations that are "associated" under the Income Tax Act, they must share one $500,000 business limit between them rather than each getting their own.

• Two corporations are associated if one controls the other
• Also associated if the same person or group controls both
• Family members (spouse, minor children) are considered the same person for association rules
• Each associated group files an agreement allocating the shared $500,000 limit

Key Takeaways

The small business deduction is the foundation of tax planning for Ontario incorporated businesses. Understanding the rates, the passive income grind-down, and the associated corporation rules allows you to structure your affairs to maximize the benefit. Most Ontario business owners should be aiming to keep active corporate income under $500,000 and passive investment income under $50,000 annually.