Corporate Investment Income Tax Calculator

Why Investment Income Inside a Corporation Is Taxed at 50.17 Per Cent

Active business income in an Ontario CCPC inside the small business limit is taxed at a combined rate in the low teens. Interest, rent and taxable capital gains earned by the same corporation are taxed at a combined 50.17 per cent. The gap is deliberate, and it is not a penalty so much as a prepayment.

The rate is assembled from four pieces, each of which sits in a different part of the legislation. Working through them one at a time is the only way to see which parts of the 50.17 per cent the corporation keeps and which parts come back.

The last line is the one that matters. Of the 50.17 per cent paid up front, 30.67 points are added to the corporation’s non-eligible refundable dividend tax on hand and can be recovered. The 19.50 per cent that remains is the true cost of holding the investment inside the corporation rather than personally, and it is close enough to a top personal rate net of the eventual dividend tax that the system roughly integrates.

The Refundable Half: 30.67 Per Cent, NERDTOH and the Dividend Refund

Subsection 129(4) adds 30.67 per cent of aggregate investment income to the corporation’s non-eligible refundable dividend tax on hand. That balance is a credit, not cash. It is recovered through the dividend refund in subsection 129(1), which is 38 1/3 per cent of taxable dividends paid in the year, limited to the relevant refundable dividend tax on hand balance.

Two consequences follow, and both are routinely missed. The first is that a corporation which earns investment income and pays no dividend recovers nothing at all. The refundable tax simply accumulates, and the effective rate on the investment income stays at 50.17 per cent for as long as the corporation holds the funds. The second is that the refund is driven by the dividend, not by the investment income, so a corporation can trigger a refund in a year in which it earned no investment income at all, provided the balance is there.

Because the refund rate of 38 1/3 per cent is higher than the 30.67 per cent going in, roughly $2.61 of taxable dividend releases every dollar of the pool. A corporation with a large accumulated balance cannot clear it with a small dividend.

Portfolio Dividends Are a Separate Stream Under Part IV

This is where most calculators of this kind go wrong. Dividends received from other Canadian corporations are deductible in computing taxable income under section 112, so they are not part of aggregate investment income and they are not subject to the additional refundable tax. They are instead subject to Part IV tax under subsection 186(1) at 38 1/3 per cent where the payer is not connected with the recipient.

Part IV tax is fully refundable. Every dollar of it goes into a refundable dividend tax on hand pool and comes back through the dividend refund. Which pool depends on the character of the dividend received: an eligible dividend from a non-connected corporation feeds the eligible pool, and a non-eligible dividend feeds the non-eligible pool. Merging Part IV tax into the Part I calculation on aggregate investment income overstates the tax on a dividend portfolio considerably, because it applies the additional refundable tax to income the ART never touches.

Dividends from a connected corporation, which for most owner-managed groups means a subsidiary or a sister company in which the recipient holds more than ten per cent of the votes and value, are generally free of Part IV tax except to the extent the payer itself claimed a dividend refund. Proposed rules in Bill C-31, not yet law as of October 2026, would suspend the dividend refund on a taxable dividend paid to an affiliated private or subject corporation that has a later balance-due day, for taxation years beginning on or after November 4, 2025. That mechanism is what makes a holding company structure workable, and it is the reason the holdco question and the passive income question are really the same question.

Capital Gains, the Taxable Half and the Capital Dividend Account

Only the taxable portion of a capital gain, determined under section 38, enters aggregate investment income and attracts the 50.17 per cent. The rest is genuinely better than tax free: it is added to the capital dividend account under subsection 89(1) and can be paid out to shareholders without any tax at all, provided an election under subsection 83(2) is filed using form T2054 before or at the time the dividend becomes payable.

That makes a realised capital gain the most efficient form of investment income a corporation can earn, and it is the one item on this page that favours the corporate route on its own merits. Our capital dividend account calculator tracks the running balance, which matters because the account is a moving figure rather than a fixed one: capital losses reduce it, and a late or excessive election carries a penalty tax under Part III.

The Small Business Deduction Grind Is Usually the Bigger Cost

Subsection 125(5.1) reduces the business limit by five dollars for every dollar of adjusted aggregate investment income of the associated group above fifty thousand dollars. At one hundred and fifty thousand dollars of adjusted aggregate investment income the business limit is gone entirely, and every dollar of active business income is taxed at the general rate instead of the small business rate.

The arithmetic is unforgiving. On the Ontario spread between the small business and general rates, losing the whole five hundred thousand dollar limit costs roughly seventy thousand dollars of additional tax on the active income, which is a great deal more than the retained tax on the passive income that caused it. A corporation with a profitable operating business and a growing investment portfolio can find that the last thirty thousand dollars of interest income cost it far more than thirty thousand dollars.

Two features of the grind deserve attention. It applies to the adjusted aggregate investment income of the whole associated group against a single fifty thousand dollar threshold, so a sibling corporation’s portfolio erodes this corporation’s limit. And it runs alongside, not instead of, the taxable capital reduction, which is modelled separately in our taxable capital SBD grind calculator. Where both apply, the greater reduction governs.

Adjusted aggregate investment income is also not identical to aggregate investment income. It excludes, among other things, taxable capital gains on property used in an active business, which means a gain on the sale of operating assets need not grind the limit even though it sits in aggregate investment income for the refundable tax calculation. This calculator applies the grind to the aggregate investment income figure it computes, which is conservative where such gains are present.

Rental Income and the Five Employee Line

A corporation whose principal purpose is to derive income from property is a specified investment business under subsection 125(7), and the income of a specified investment business is not active business income. It does not qualify for the small business deduction and it goes into aggregate investment income at 50.17 per cent. There is one exception: a corporation that employs more than five full-time employees throughout the year is outside the definition.

The wording is more than five, not five or more. A rental corporation with exactly five full-time employees is a specified investment business. This is a bright line that has been litigated repeatedly, and the arguments turn on what counts as full time and what counts as throughout the year. Part-time staff, contractors and the owner’s own unpaid effort generally do not help.

The employee test cuts both ways. Where a rental operation genuinely does have more than five full-time employees, the income is active business income, it is not aggregate investment income, and it does not grind the business limit. That is a materially better outcome, and it is worth establishing properly rather than assuming. Please do not restructure staffing to reach a threshold without advice, because the CRA looks at substance and the general anti-avoidance rule is available to it.

Should You Invest Through Your Corporation?

The honest answer is that the corporate route rarely offers a permanent saving on the investment return itself. The system is designed to integrate, and on interest income the combined corporate and personal tax on a dollar earned in the corporation and paid out as a dividend lands close to what the same dollar would have cost personally. Sometimes it is slightly better and sometimes slightly worse, depending on the province and the year.

What the corporation does offer is a deferral on the capital. Active business income taxed at the small business rate leaves considerably more to invest than the same income taken as salary and taxed personally, and a larger pool compounding for a long period is a real advantage even if the return on it is taxed no more kindly. That advantage is on the money going in, not on the income coming out.

Against that sits the small business deduction grind, which is a genuine permanent cost rather than a timing one, and which frequently exceeds the tax on the investment income that triggered it. A corporation with an operating business earning at or below the business limit should be very deliberate about pushing adjusted aggregate investment income past fifty thousand dollars. Where the portfolio is already large, separating it from the operating company, using individual pension plans or permanent insurance, or simply holding some of it personally are all worth costing properly as part of tax planning rather than decided by default.

What This Calculator Does Not Cover

• Foreign investment income and foreign tax credits, including the deductions in subsections 20(11) and 20(12) and the interaction of withholding tax with the refundable tax calculation
• Foreign accrual property income from a controlled foreign affiliate, which is a separate inclusion with its own relief mechanism
• The eligible and non-eligible dividend designation mechanics, the general rate income pool and the excessive designation penalty under Part III.1
• Refundable dividend tax on hand transitional balances from the 2019 split of the single pool into eligible and non-eligible accounts
• Associated corporation sharing of the fifty thousand dollar passive income threshold and of the business limit itself
• Provincial differences outside Ontario, where both the general rate and the small business rate differ and some provinces do not mirror the federal grind
• The taxable capital reduction in subsection 125(5.1) and how it interacts with the passive income grind when both apply
• Adjusted aggregate investment income adjustments, including the exclusion of gains on active business property and of certain dividends
• Capital losses, net capital loss carryovers and their effect on both aggregate investment income and the capital dividend account
• Insurance, individual pension plans and other alternatives to holding a portfolio directly in the corporation

Passive income inside a CCPC is a planning problem, not a compliance problem. By the time the T2 is prepared the grind has already happened. Our corporate tax return filing service covers Schedule 7, the refundable tax calculation and the dividend refund, and we would rather look at the portfolio before the year end than after it.