Short answer
Deductibility generally follows the current use of the borrowed money—not simply the property used as collateral. Clear tracing, a legal obligation to pay interest and an eligible income-earning purpose are central.
The homeowner’s practical concern
A homeowner refinances the principal residence, mixes investment and personal spending in one account and assumes all interest becomes deductible because the loan is secured by a house.
What the official rule says
CRA’s interest-deductibility folio requires a direct link between borrowed money and an eligible use, subject to the Income Tax Act and case law. Mixed-use borrowing creates tracing and repayment complexity.
What this does not guarantee
Using a rental property as security does not make personal borrowing deductible, and using a home as security does not automatically prevent a properly traced investment-purpose deduction. Mortgage approval is separate.
A practical Ontario example
Illustration only: From one refinance, $100,000 buys an income-producing investment and $50,000 pays personal debt. Treating the entire loan as deductible would ignore the separate uses.
What to check before changing the property or mortgage
Use distinct loan segments and accounts where practical, preserve transfer records and obtain tax advice before funds move. Ask the broker to structure the credit so the intended uses remain visible.
- How has the property actually been used each year?
- Was CCA claimed, and was any section 45 election filed?
- What was the property’s fair market value when its use changed?
- Where will refinance proceeds go, and can every transfer be traced?
- Which point needs written tax or legal advice before funds move?
Rajiv’s broker perspective
A mortgage approval answers whether a lender will finance the borrower and property under that lender’s policy. It does not confirm a tax deduction, principal-residence exemption, election or municipal-tax exemption. Before refinancing, changing occupancy or building a suite, I would separate the mortgage objective from the tax assumption, preserve the money trail and compare A-lender, alternative/B, MIC or private options only after the real use and exit plan are clear.
Related: Mortgage Knowledge Centre · Real Estate Centre · Updates & Rules Centre
Planning a refinance, rental conversion or family suite?
Send Rajiv the property use, ownership, mortgage balance, proposed funds and future plan. He can pressure-test the financing and identify tax questions that should be confirmed before the structure becomes difficult to unwind.
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