One of the most powerful tax advantages available to incorporated small businesses in Ontario is the Small Business Deduction (SBD). It allows Canadian-Controlled Private Corporations (CCPCs) to pay a dramatically lower tax rate on the first $500,000 of active business income each year. Here’s what every Ontario business owner needs to know.
What Is the Small Business Deduction?
The SBD is a federal and provincial tax reduction that lowers the corporate tax rate on the first $500,000 of active business income earned by a CCPC. This threshold is called the Business Limit.
In Ontario, the combined federal-provincial tax rate on income eligible for the SBD is approximately 12.2%, compared to the general corporate rate of approximately 26.5%. That’s a difference of over 14 percentage points — or more than $70,000 in tax savings on a full $500,000 of income.
Federal vs. Ontario Small Business Rates (2026)
- Federal small business rate: 9%
- Ontario small business rate: 3.2%
- Combined Ontario rate (SBD eligible income): ~12.2%
- Combined Ontario general rate (above $500K): ~26.5%
What Qualifies as Active Business Income?
Not all corporate income qualifies for the SBD. Active business income includes revenue from your core business operations — professional services, contracting, retail, consulting, etc. It does not include:
- Investment income (interest, dividends, rent from a related party)
- Income from a Specified Investment Business (primarily earning passive income)
- Income from a Personal Services Business (essentially an employee-employer relationship run through a corporation)
The Passive Income Grind-Down
Since 2019, the Business Limit is reduced — or “ground down” — when a CCPC (or associated group) earns more than $50,000 in passive investment income in the prior year. The SBD is eliminated entirely at $150,000 of passive income.
This is a critical planning issue for business owners who have accumulated significant investment portfolios inside their corporation. If passive income is approaching $50,000, proactive restructuring may be needed to protect SBD eligibility.
Associated Corporations
The $500,000 Business Limit must be shared among associated corporations. If you own two or more corporations that are associated (common ownership or control), they collectively share one $500,000 limit — not $500,000 each. Failure to properly allocate the limit among associated corporations is a common CRA audit issue.
Why This Matters for Your Tax Planning
The SBD is the primary reason incorporation is attractive for many small business owners. The ~14% rate differential between the SBD rate and the general rate creates a significant tax deferral opportunity: income earned in the corporation is taxed at 12.2%, leaving 87.8 cents of every dollar available for reinvestment — versus taking it as personal income where marginal rates can exceed 50% in Ontario.
This deferral is most powerful when combined with a deliberate salary/dividend strategy and long-term investment planning inside the corporation.
Common Mistakes That Cost Business Owners the SBD
- Letting passive investment income creep above $50,000 without a plan
- Not properly tracking associated corporation relationships
- Misclassifying what counts as active vs. passive income
- Ignoring the Personal Services Business rules when contracting through a corporation
The Small Business Deduction is powerful — but only if structured correctly. Contact CMP Accounting to make sure your corporation is set up to maximize it.