The Small Business Deduction in Canada, Explained

If you own a Canadian corporation, you have likely heard that small businesses pay a lower tax rate than large ones. That lower rate exists because of the small business deduction (SBD) — a federal tax provision that substantially reduces the corporate income tax rate on the first portion of active business income earned by a qualifying corporation.

Understanding the small business deduction in Canada is fundamental to appreciating why incorporation is often attractive for business owners, and also to understanding its limits. The SBD is not a simple flat benefit — it comes with qualifying conditions, an income cap called the small business limit, and several rules that can reduce or eliminate it in certain circumstances.

This article explains the SBD in plain language. Rates and thresholds change regularly — treat all figures in this article as illustrative and confirm current numbers with the CRA or your accountant before making financial decisions.

What the Small Business Deduction Actually Does

Canadian corporations generally pay federal corporate income tax on their taxable income. The general federal corporate rate applies to most business income. However, Canadian-controlled private corporations (CCPCs) — meaning privately held corporations controlled by Canadian residents — are eligible for the SBD, which reduces the federal rate on qualifying income.

The result is a significantly lower combined federal-provincial effective rate on the first tranche of income, compared to both the general corporate rate and personal marginal rates. This rate gap is the engine behind the tax deferral benefit of incorporation discussed in our incorporation tax benefits article.

To verify the current federal small business rate, the general corporate rate, and Ontario's matching provincial rates, visit the CRA website or speak with an accountant.

What Qualifies: Active Business Income

The SBD only applies to active business income (ABI) — broadly, income from carrying on a business actively, as opposed to passive investment income.

Active business income typically includes:

• Revenue from selling goods or services
• Fees earned in a professional practice
• Income from a business activity the corporation actively manages

Active business income does not include:

• Interest income, dividends, and capital gains from investments
• Rental income from property that is not actively managed as a business
• Income from a specified investment business (a business whose principal purpose is to earn investment income from property)
• Income from a personal services business — a structure where an individual provides services through a corporation to essentially one client and would be considered an employee but for the corporation

If a significant portion of your corporation's income is passive, only the active business income portion qualifies for the SBD.

The Small Business Limit

The SBD does not apply to all active business income, only up to a ceiling called the small business limit. Income above this threshold is taxed at the full general corporate rate. The federal small business limit is set by Parliament and has changed over time — confirm the current figure with the CRA or your accountant.

Ontario has its own small business limit for provincial corporate tax purposes, which may differ from the federal limit.

What Can Reduce the Small Business Limit

Several rules can reduce — or even eliminate — the small business limit available to a particular corporation. These are important to understand because they can significantly change the tax calculation.

Associated Corporations

If you and your spouse (or another family member or business partner) each own a separate corporation, and those corporations are associated under the tax rules, they must share a single small business limit. Two associated corporations cannot each claim the full limit independently.

Corporations are associated if one controls the other, both are controlled by the same person or group, or there is a common ownership arrangement meeting certain thresholds. The associated corporation rules are designed to prevent business owners from multiplying the SBD by fragmenting a business into many small corporations.

This is a common surprise for business owners who operate multiple companies. If you run several corporations, their association status should be reviewed annually by your accountant.

The Passive Income Grind

The federal government introduced rules that reduce the small business limit when a CCPC (or an associated corporation) earns significant adjusted aggregate investment income (AAII) — essentially, passive investment income earned inside the corporation.

The grind works progressively: as passive income inside the corporate group rises above a threshold (verify current threshold with the CRA), the small business limit is reduced. At a higher level of passive income, the small business limit is reduced to zero, meaning all income is taxed at the general corporate rate.

The practical implication is that using a corporation as a holding vehicle for large investment portfolios can erode the SBD benefit on active business income. This is a planning issue, not simply an accounting one — how you structure investment assets (inside vs. outside the corporation, in a holding company vs. operating company) affects the tax cost.

The Taxable Capital Threshold

Large corporations — those with taxable capital employed in Canada above a certain threshold — also face a reduction in the small business limit. This is primarily a concern for larger businesses and associated corporate groups, not early-stage small businesses.

Integration: The Big Picture

The SBD does not make corporate income permanently cheaper than personal income. The concept of tax integration in the Canadian system means that, in theory, income earned through a corporation and ultimately distributed to a shareholder should attract roughly the same total tax (corporate plus personal) as income earned directly by the individual.

In practice, integration is imperfect, and there are timing advantages (deferral), but the SBD is not a permanent escape from tax — it is a deferral and, in some cases, a modest permanent saving depending on the province and the individual's tax rate.

Ontario's Small Business Rate

Ontario levies its own provincial corporate income tax. Ontario has a reduced rate that applies to small business income up to its own provincial small business limit. The combined federal-provincial effective rate on qualifying small business income in Ontario is among the lowest in Canada for income within the limit — but confirm the current rate with your accountant, as it is subject to change.

Frequently asked questions