Investing inside your corporation: what the passive income rules cost you

Summary

If your corporation earns more than you need to live on, you can leave the surplus inside the corporation and invest it there, rather than paying it out to yourself first. Tax rules call the money a corporation earns from investments passive income (i.e. interest, rent, dividends and gains on things it owns), as opposed to the active income it earns by doing the work, and everything below says “investment income” for the passive kind.

In Ontario, a corporation pays about 11.7% in total corporate tax on its first $500,000 of active business income for a year ending December 31, 2026.¹ The 11.7% is the 9% federal small business rate plus Ontario’s own rate, which is 3.2% until June 30, 2026 and 2.2% after that. You’d pay up to about 53.5% on that same dollar personally in 2026. Your corporation therefore keeps about $0.88 of each pre-tax dollar to invest, where you’d have kept about $0.46.²

Two rules claw some of that advantage back, and both cost less than owners are usually told:

1. The investments your corporation buys, whether stocks, funds, GICs or rental property, earn money of their own, and your corporation pays roughly 50% tax on that in Ontario in 2026. About 30 of those 50 percentage points come back as a refund, but only when it pays dividends to you.³
2. Investment income also shrinks the amount of business profit that qualifies for the 9% rate. Every $1 above $50,000 in a year costs your corporation $5 of that $500,000 allowance, so once investment income reaches $150,000 the allowance is gone. Accountants call the allowance your federal small business limit, and the reduction the grind. The grind runs off last year’s investment income, across every corporation you and your family control.⁴

We’d fill your personal registered accounts before anything else, starting with a TFSA (i.e. a tax-free savings account), and then an RRSP, meaning a registered retirement savings plan, if you pay yourself a salary. After that, invest the rest inside the corporation and watch how much taxable income the investments throw off, rather than restructuring the company to dodge the grind. That recommendation changes if you might sell the business within about three years. Our corporate tax calculator shows what last year’s investment income does to this year’s small business limit.

Where the money to invest comes from

On $100,000 of pre-tax profit in Ontario for a year ending December 31, 2026, your corporation has about $88,300 to put to work. The same profit paid to you as salary would have left you about $46,500. Accountants call the gap a deferral, meaning tax paid later rather than never, because paying it out to you later costs close to what the salary would have. What you actually keep is the return earned by the extra $41,800, for as long as it stays invested. At a 6% return that’s roughly $6,400 after three years and roughly $65,600 after twenty, less the personal tax you eventually pay on those earnings.⁵

What your corporation pays on what the investments earn

In Ontario for 2026, three kinds of investment income are taxed at roughly 50% in total, federal and Ontario corporate tax combined.³ They are interest, rent after the expenses of earning it, and the taxable portion of a gain your corporation realizes. Investment income gets neither the 9% rate nor the discount on business profit above the $500,000 limit.

Your corporation really does hand all 50% of that to the CRA. About 30 of those 50 percentage points, sometimes slightly less, go into a running tally in your corporation’s tax file. The tally is called refundable dividend tax on hand, and the CRA hands that amount back later.⁶ Nothing comes back automatically: the refund arrives only when your corporation pays dividends to you, at about 38 cents for every $1 of dividends paid. Clearing $1 out of the tally therefore takes about $2.60 of dividends. The two percentages measure different things: 30% of what the investments earned goes into the tally, and 38% of the dividends you pay comes out. Net of the refund, permanent corporate tax on investment income in Ontario is closer to 20% than to 50%, but only for a corporation that pays dividends periodically rather than never.

Only half of a realized capital gain is taxable, and the untaxed half credits the capital dividend account, which your corporation can pay out to you free of personal tax if it files a formal election with the CRA first.⁷ An investment that has gone up in value but that your corporation hasn’t sold isn’t taxed, and doesn’t count toward the $50,000 and $150,000 thresholds below. Pooled funds are the exception, since they pass out the interest and gains realized inside the fund whether or not you sell.

The rule that shrinks your small business limit

Your corporation’s federal small business limit is the first $500,000 of active business income each year that qualifies for the 9% federal rate rather than the 15% federal rate charged above it. Investment income over $50,000 in a year, measured by a rule called adjusted aggregate investment income, cuts that $500,000 by $5 for every extra $1.⁴ Three details of the reduction do most of the damage in practice:

• The investment income counted is the prior calendar year’s, so for a corporation with a December 31 year end, what the investments earn in 2026 sets the small business limit for 2027, well after the cash has been reinvested or spent.
• The figure is added up across your associated group, which broadly means corporations under common control. The group also catches corporations controlled separately by related people, where one of those people holds at least 25% of a class of shares of the other.⁸ A second company doesn’t buy a second $50,000 threshold, and moving investments to a related company doesn’t work either.⁹
• What counts is broader than owners expect: interest, rent after expenses and foreign dividends all count in full. Dividends from Canadian public companies count in full too, even though they’re taxed under a separate mechanism rather than at the 50% rate above. Realized capital gains count at half, and gains on assets the business actually uses are excluded (e.g. the building you operate from).¹⁰

Losing the whole $500,000 of limit moves that profit from 9% to 15%, which is at most $30,000 a year of extra federal tax.¹¹ Ontario adds nothing on top, because it chose not to copy the federal rule and leaves its own $500,000 limit alone whatever your investment income does.¹² Even the $30,000 is mostly not permanent, because business profit taxed at 15% builds a balance in your corporation’s records. That balance is what lets your corporation pay you “eligible” dividends, which cost you less personal tax than ordinary ones. Much of the extra tax therefore comes back when the money is distributed, and how much depends on your personal bracket in the year you take it out.

What we’d do

Ranked in order, with what each one costs:

1. Use up your TFSA contribution room first, meaning what you’re allowed to put in this year plus anything unused from past years. Then use your RRSP room, but only if you pay yourself a salary, since salary is what creates RRSP room and dividends create none. The cost is personal tax on the way out, and annual room that’s small next to most corporate surpluses.
2. Invest whatever’s left inside the corporation with no new structure, which keeps the full deferral and adds no filings. The costs are roughly 20 points of permanent corporate tax on the investment income, plus creditor exposure. If the business is sued or fails, the investments sit in the same company and can be claimed by its creditors.
3. Watch how much taxable income your corporation’s investments produce each year, which moves the grind more than anything else you control, because only realized income counts. To provide an example, $1,000,000 earning 4% interest produces $40,000 of investment income every single year. The same $1,000,000 in something whose return is mostly growth your corporation hasn’t sold produces investment income only on what it distributes. The point is a tax consequence rather than a portfolio recommendation, and volatility is wrong for money the business might need soon.

One condition flips all of this: if selling the business is plausible within about three years, we’d plan now to move surplus investments out. A large portfolio can disqualify your shares from the lifetime capital gains exemption, which shelters roughly the first $1,275,000 of your gain when you sell. More than half the asset value must meet the active-business test throughout the preceding 24 months, and almost all must qualify at sale. A smaller portfolio can therefore be removed closer to closing, but a company that fails the lookback needs time to rebuild eligibility.¹³

How often this changes

Re-run this once a year, about two months before your corporation’s year end, while you can still act on the answer. Re-run it earlier if your investment income is anywhere near $50,000 or $150,000, if a sale of the business or a property is coming, or if your active business income is between $300,000 and $500,000, where every dollar of limit you lose is a dollar you were actually using.

Closing thoughts

The $50,000 threshold is a policy choice rather than a principle. Introduced in the 2018 federal budget at roughly the yield on $1,000,000 at 5%, it hasn’t been indexed since, and at today’s rates it catches balance sheets it was never aimed at.¹⁴ Owners hear “roughly 50% tax” and “you lose your small business rate” and conclude that leaving money in the corporation is a mistake. For most of them the arithmetic says the opposite, and the bigger risk we see is money stripped out early at top personal rates.

How we handle it

We calculate the investment income figure the grind runs on as part of your corporate tax return. Before your year end we tell you what it does to next year’s small business limit, and to next year’s instalments (i.e. the tax your corporation pays in advance during the year, which rises when the bill it’s based on rises). We track the capital dividend account and the refundable tax balance, and set a dividend plan that recovers the refund rather than leaving it with the CRA. We do the tax side and don’t give investment advice, so what the portfolio holds stays with you and your adviser. Planning of this kind sits in the Year-Round Tax Partner package, and our pricing page sets out what each package covers.