Start with the rate table nobody puts in the pitch
The small business deduction applies to active business income, and a corporation holding your portfolio does not earn that. Its gains, interest and dividends are investment income, taxed at roughly 50% in Ontario when earned, with a large slice refunded only when the corporation pays you taxable dividends, on which you then pay personal tax. The system is built so that routing a portfolio through a company saves nothing on rate; it mostly adds filings.
| Income inside the corporation | Tax when earned | What flows back out |
|---|---|---|
| Capital gains on the book | Half is investment income taxed near 50% | The untaxed half enters the capital dividend account, payable to you tax-free |
| Interest and income-account trading profits | Fully taxed near 50% | Roughly 30.67 points refundable as taxable dividends are paid |
| Dividends from Canadian portfolio stocks | Part IV tax at 38.33% | Refundable when taxable dividends are paid out |
| Genuine active business income | About 12.2% on the first $500,000 | The rate a personal trading book does not qualify for |
Set that against the personal alternative: half the gain at your marginal rate, once, with no second layer and no corporate return. That is the baseline every trading-corporation pitch has to beat, and few do.
What the corporation costs beyond the rate
- Trapped losses. A bad year inside the corporation offsets nothing on your personal return; the losses wait for corporate gains that may be years away.
- No capital gains exemption. The $1.25M lifetime exemption requires qualified small business corporation shares, and a company whose main asset is a brokerage account fails that test on day one.
- Annual overhead. A T2 return, a minute book, separate brokerage and bank accounts, and the discipline of never routing a personal trade through the corporate book.
- No real liability story. The usual limited-liability argument barely applies: the capital at risk in a trading account is the money you put into it, and incorporation does not change whose money that is.
If you already own an operating company, the trap runs the other way. Once an associated group's adjusted aggregate investment income passes $50,000 in a year, the $500,000 small business limit shrinks by $5 for every extra dollar and disappears at $150,000. A trading book run on corporate cash can quietly strip the 12.2% rate from the business that actually earns it, and shifting the portfolio into a holding company does not fix this, because associated corporations are counted together.
The cases where the math genuinely clears
Dollars already inside a company change the question. An owner-manager whose profits sit as retained earnings can invest the corporate dollar, about 88 cents after the small business rate, instead of the smaller dollar left after personal tax at rates that top out above 53% in Ontario. The advantage is the deferral on the way in, not anything about how the investment income itself is taxed, and weighing it against your spending needs is structuring work, the kind our founder Walla Assaf spent a banking career doing.
Funded and prop-firm traders are the other real case. A payout under a profit split with a funding firm is business income for a service you provide, not a return on your own capital, and business income is exactly what a corporation is built to hold. Whether the numbers justify it depends on the contract and on how much of the income you live on each year, which is a calculation, not a slogan. One boundary flag before any structure talk: trading anyone else's money brings Ontario securities registration requirements that no corporate setup replaces.
How we decide it with you
Our Incorporation engagement for traders starts by trying to talk you out of it with your own numbers: expected gains, income-account versus capital-account character, personal cash needs and what you already hold corporately. If the structure clears, we incorporate it properly and set up the capital dividend account tracking and refundable tax pools so money can come back out the cheap way. If it does not, Tax Planning & Advisory usually finds more value in account placement and timing than a company would have added. Either way the fee is quoted in writing after a free 15-minute discovery call, from our office in Mississauga.
