In Canada, mortgage interest on your principal residence is not tax deductible. This is one of the biggest differences between the Canadian and American tax systems. But there are several legitimate scenarios where mortgage interest is deductible — and understanding them can save you thousands of dollars per year.
The basic rule
| Scenario | Interest Deductible? | CRA Basis |
|---|---|---|
| Mortgage on your principal residence | ❌ No | Personal expense |
| Mortgage on a rental property | ✅ Yes | Income-producing expense (T776) |
| Mortgage on a property used partly for rental | ✅ Proportional | Based on rental-use percentage |
| HELOC used to buy investments | ✅ Yes | Borrowed to earn income (Line 22100) |
| HELOC used to buy a rental property | ✅ Yes | Borrowed to earn rental income |
| HELOC used for personal expenses | ❌ No | Personal expense |
| Home office mortgage interest (self-employed) | ✅ Proportional | Business-use-of-home expense |
| Home office (salaried employee with T2200) | ✅ Limited | Employment expense |
The CRA rule is simple: interest is deductible when the borrowed money is used for the purpose of earning income (rental income, investment income, or business income). The security for the loan does not matter — what matters is how the borrowed funds are used.
Scenario 1: Rental property mortgage interest
If you own a property and rent it out, the mortgage interest is fully deductible against your rental income.
What you can deduct
| Expense | Deductible? | Where to Report |
|---|---|---|
| Mortgage interest | ✅ Yes (interest only, not principal) | T776 Line 8710 |
| Property taxes | ✅ Yes | T776 Line 9180 |
| Insurance | ✅ Yes | T776 Line 8690 |
| Repairs and maintenance | ✅ Yes | T776 Line 8960 |
| Property management fees | ✅ Yes | T776 Line 8860 |
| Utilities (if you pay them) | ✅ Yes | T776 Line 9200 |
| Mortgage principal repayment | ❌ No | Not an expense |
| CCA (capital cost allowance) | ✅ Yes (optional — be cautious) | T776 |
Example: Rental property deduction
| Item | Amount |
|---|---|
| Annual rental income | $24,000 |
| Mortgage interest (not principal) | $14,400 |
| Property tax | $4,200 |
| Insurance | $1,800 |
| Repairs | $2,000 |
| Total deductible expenses | $22,400 |
| Taxable rental income | $1,600 |
Without the mortgage interest deduction, you would pay tax on $16,000 of rental income instead of $1,600.
Important: Interest only, not principal
Your mortgage payment includes both principal and interest. Only the interest portion is deductible. Your lender provides an annual mortgage statement showing the interest and principal breakdown.
| Monthly Payment | Interest Portion | Principal Portion | Deductible |
|---|---|---|---|
| $2,200 | $1,200 | $1,000 | $1,200 |
Over the life of the mortgage, the interest portion decreases and the principal portion increases. Your deduction shrinks over time.
Scenario 2: Mixed-use property (part rental)
If you rent part of your home (e.g., a basement suite), you can deduct a proportional share of your mortgage interest.
How to calculate the rental portion
| Method | How It Works |
|---|---|
| Square footage | Rental area ÷ total area = rental percentage |
| Number of rooms | Rooms rented ÷ total rooms = rental percentage (less common) |
Example: Basement suite
| Factor | Amount |
|---|---|
| Total home area | 2,000 sq ft |
| Basement suite area | 600 sq ft |
| Rental percentage | 600 ÷ 2,000 = 30% |
| Annual mortgage interest | $18,000 |
| Deductible portion | $18,000 × 30% = $5,400 |
| At 40% marginal tax rate | $2,160 annual tax savings |
Also deductible at 30%: property taxes, insurance, utilities, repairs to common areas. Repairs specific to the rental suite are 100% deductible.
CCA warning for mixed-use properties
You can claim Capital Cost Allowance (CCA) on the rental portion of your home, but this is generally not recommended for your principal residence. Claiming CCA on a portion of your home reduces the adjusted cost base and may trigger a partial capital gains liability when you sell — eroding or eliminating the principal residence exemption on that portion.
Scenario 3: HELOC used for investing (Smith Manoeuvre)
If you borrow against your home using a HELOC and invest the borrowed funds in income-producing assets, the HELOC interest is tax deductible.
| Component | Details |
|---|---|
| How it works | Reborrow mortgage principal via HELOC; invest in dividend-paying stocks/ETFs |
| Interest deductible? | ✅ Yes — borrowed to earn investment income |
| Where to report | Line 22100 — Carrying charges and interest expenses |
| Documentation required | Separate HELOC sub-account; dated records linking each advance to each investment purchase |
| What qualifies | Investments that have a reasonable expectation of producing income (dividends, interest) |
Full guide: The Smith Manoeuvre: Make Your Mortgage Tax Deductible
Scenario 4: HELOC used to buy a rental property
If you take a HELOC on your principal residence and use those funds to purchase a rental property, the HELOC interest is deductible — because the borrowed money is used for income-producing purposes.
This is the CRA’s interest tracing rule in action: it doesn’t matter what property secures the loan. What matters is how the money is used.
| Situation | Loan Secured By | Funds Used For | Interest Deductible? |
|---|---|---|---|
| HELOC on home → buy rental property | Principal residence | Rental income | ✅ Yes |
| HELOC on home → buy investments | Principal residence | Investment income | ✅ Yes |
| HELOC on home → renovate home | Principal residence | Personal use | ❌ No |
| HELOC on home → pay off car loan | Principal residence | Personal use | ❌ No |
| Mortgage on rental → buy rental | Rental property | Rental income | ✅ Yes |
Scenario 5: Home office (self-employed)
If you are self-employed and use a dedicated portion of your home for business, you can deduct a proportional share of mortgage interest as a business expense.
Requirements
| Requirement | Details |
|---|---|
| Dedicated space | Used primarily (>50%) for business and for meeting clients, OR used exclusively for business and on a regular basis |
| Self-employed | Must be self-employed (not incorporated — corporations have different rules) |
| Where to report | Form T2125 — Business-use-of-home section |
Deductible expenses (proportional)
| Expense | Deductible Portion |
|---|---|
| Mortgage interest | Home office % |
| Property taxes | Home office % |
| Utilities (heat, electricity, water) | Home office % |
| Home insurance | Home office % |
| Repairs to office space | 100% |
| Repairs to common areas | Home office % |
| Mortgage principal | ❌ Not deductible |
Example: Self-employed home office
| Factor | Amount |
|---|---|
| Home office area | 200 sq ft |
| Total home area | 1,800 sq ft |
| Business-use percentage | 200 ÷ 1,800 = 11.1% |
| Annual mortgage interest | $16,000 |
| Deductible portion | $16,000 × 11.1% = $1,776 |
Limitation: Home office expenses cannot create or increase a business loss. If your business income (before home office expenses) is $0 or negative, you carry forward the home office deduction to a future year.
Scenario 6: Salaried employee working from home
If your employer requires you to work from home and provides a signed T2200 form, you can deduct a proportion of certain home expenses including mortgage interest — but with more restrictions than self-employed.
| Method | How It Works | Maximum |
|---|---|---|
| Simplified flat rate | $2 per day worked from home | $500/year |
| Detailed method (T2200) | Proportional home expenses | No fixed maximum |
Under the detailed method:
| Expense | Commission Employee | Salaried Employee |
|---|---|---|
| Mortgage interest | ❌ No | ❌ No |
| Rent | ✅ Yes | ✅ Yes |
| Utilities | ✅ Yes | ✅ Yes |
| Insurance | ✅ Yes | ❌ No |
| Property taxes | ✅ Yes | ❌ No |
Note: Salaried employees generally cannot deduct mortgage interest even with a home office. This deduction is primarily available to self-employed individuals reporting on T2125 and to commission-based employees in limited circumstances.
CRA documentation and audit risk
| What to Keep | Why |
|---|---|
| Annual mortgage statement (interest vs principal breakdown) | Proves the interest amount claimed |
| T776 (rental) or T2125 (business) | Shows the calculation |
| Lease agreements with tenants | Proves rental income/expense |
| HELOC statements separated by purpose | Proves investment vs personal use |
| Investment purchase confirmations | Links borrowed funds to investments (Smith Manoeuvre) |
| Floor plan or measurement showing office/rental area | Supports proportional claim |
| T2200 (signed by employer) | Required for employee home office claims |
Common CRA audit triggers
| Red Flag | Why It Triggers Review |
|---|---|
| Rental losses year after year | CRA questions whether there’s a reasonable expectation of profit |
| Mixed-use HELOC with single interest deduction | CRA can’t tell investment vs personal use |
| Home office > 25% of home | Unusual proportion raises questions |
| Claiming CCA on principal residence | Signals possible PRE issues |
| Large interest deductions relative to rental income | CRA may investigate to ensure property is actually rented |
Summary: When mortgage interest is deductible
| Situation | Deductible? | How Much | Where to Report |
|---|---|---|---|
| Principal residence mortgage | ❌ | $0 | — |
| Rental property mortgage | ✅ | 100% of interest | T776 |
| Mixed-use property (part rental) | ✅ | Rental % of interest | T776 |
| HELOC → invest in stocks/ETFs | ✅ | 100% of HELOC interest | Line 22100 |
| HELOC → buy rental property | ✅ | 100% of HELOC interest | T776 |
| HELOC → personal use | ❌ | $0 | — |
| Home office (self-employed) | ✅ | Office % of interest | T2125 |
| Home office (salaried, T2200) | ❌ (usually) | $0 (most cases) | T777 |