Finance

Thin Capitalization Rules Canada

Amy Richards | February 20, 2026 | 4 min read

What Are Thin Capitalization Rules?

Thin capitalization rules limit the amount of interest a company can deduct when it has too much debt relative to equity. In Canada, the federal thin cap rules (ITA Section 18.2) apply when a Canadian-controlled private corporation (CCPC) or any corporation has outstanding debts to non-resident shareholders or their affiliates exceeding a 1.5:1 debt-to-equity ratio.

The rules target situations where debt is used to strip profits out of a corporation in the form of interest deductions, while equity is left thin.

The Debt-to-Equity Ratio Test

The thin cap threshold in Canada is a 1.5:1 debt-to-equity ratio. The formula is:

Debt/Equity = Total Debt Owed to Non-Residents ÷ Applicable unused thin capitalization surplus

• Debt: Amounts owed to non-resident shareholders (or associates) by the corporation
• Equity: The corporation's "thin capitalization surplus" — essentially the non-debt capital contributions

Consequences of Failing the Test

When the 1.5:1 ratio is exceeded, the corporation loses the interest deduction on the excess debt. The disallowed interest is simply added to the corporation's income — it is not permanently lost, but the tax benefit of the interest deduction is denied in that year.

• Excess interest is added to corporate income
• Corporate tax rate applied to the added income (roughly 15-26.5% federally + provincial)
• No deduction in the year, but may carry forward unused portion (subject to limits)

Planning Tips

• Keep debt-to-equity below 1.5:1 to avoid disallowance
• Consider converting some debt to equity (shareholder contributions) before year-end
• Use multiple non-resident creditors or restructure to stay under the threshold
• Note: provincial thin cap rules may differ — check the applicable provincial rules

Internal links (related)

• WACC
• Free Cash Flow
• DCF Valuation