How much can I afford?
What a bank will lend you and what you should actually spend are two different numbers. Here's how lenders think about it — and how you should think about it too.
The mortgage stress test
Canada's mortgage stress test — set by OSFI stress test guidelines — requires lenders to qualify you at a rate higher than what you're actually borrowing at. The qualifying rate is the higher of two numbers: your actual contract rate plus 2 percentage points, or the government's minimum qualifying rate floor [verify current figures with a licensed agent or at realtor.ca]. The floor exists so that even when rates are low, buyers aren't qualifying for more than they can realistically handle if rates rise.
In practice, this means if you're borrowing at 5.0%, you qualify at 7.0%. The bank calculates how much you can borrow at 7.0%, and that's your ceiling — even though your actual payments will be based on 5.0%. It's a meaningful difference. The stress test typically reduces your maximum borrowing amount by 15–20% compared to qualifying at the actual contract rate.
Example: A household earning $120,000 combined might qualify for roughly $680,000 at a 5.0% contract rate after the stress test — but without the stress test, the same income might have qualified them for $800,000 or more. The test keeps people from stretching to their absolute limit.
GDS and TDS ratios
Lenders use two ratios to decide how much you can borrow. Understanding these helps you see exactly where your ceiling comes from.
Gross Debt Service (GDS)
Maximum share of gross monthly income that can go toward housing: mortgage principal + interest + property taxes + heating + 50% of condo fees.
Total Debt Service (TDS)
Maximum share of gross monthly income that can go toward all debts: housing costs above plus car loans, student loans, credit card minimum payments.
Both ratios are calculated using your gross (pre-tax) income, not your take-home pay. If your gross monthly income is $8,000, your maximum GDS payment is $3,120 and your maximum TDS (all debts combined) is $3,520. Every car loan or student loan payment you're carrying reduces how much you can borrow for a home.
Pre-qualification vs. pre-approval: not the same thing
Pre-qualification is informal. You tell a lender your income, debts, and assets, and they estimate how much you might borrow. Nothing is verified. The number they give you is a rough estimate — useful for orientation, not for making offers.
Pre-approval is a real commitment. You submit pay stubs, T4s, bank statements, and your Notice of Assessment. The lender reviews and verifies everything, runs a credit check, and issues a written commitment at a specific rate for 90 to 120 days. With pre-approval, you know your real ceiling, you're protected against rate increases during your search, and sellers take you seriously. Don't make an offer without it.
Important: Pre-approval is conditional. The lender still needs to approve the specific property you're buying. If the home appraises below the purchase price, your financing may come in lower than expected. Discuss appraisal risk with your mortgage broker before you remove your financing condition.
Worked example: A $120,000 household income
Qualifying scenario
Note that $440,000 in mortgage borrowing doesn't mean a $440,000 house. Add your down payment to get the purchase price. If you've saved $100,000 for a down payment, this household's realistic budget is around $540,000.
What the bank will lend vs. what you should spend
Banks will lend you up to your maximum. That doesn't mean you should borrow the maximum. Housing costs that consume 39% of your gross income leave very little flexibility for job changes, unexpected expenses, saving for retirement, or the ordinary costs of maintaining a property. Many financial advisors suggest targeting GDS around 28–32% — well below the maximum — as a more comfortable ceiling.
Think honestly about your situation. If you're planning to have children, one income may carry the mortgage for a period. If your job is variable or commission-based, a conservative ceiling protects you. If you have no other debt and strong income stability, you have more room. The bank's ceiling is a maximum, not a recommendation.
Practical tool: PropertyProperty.ca has a free affordability calculator — enter your income, debts, and down payment to see your realistic ceiling before you meet with a lender. Walking in with a realistic range makes the conversation much more useful.
What you need for pre-approval
Gather these before you sit down with a lender or mortgage broker:
Two years of T4 slips and Notices of Assessment. Three most recent pay stubs. Three months of bank statements showing your down payment funds. If self-employed: two years of financial statements and your most recent two tax returns. A list of all monthly debt payments. Photo ID.
If your down payment is partly from a gift from a family member, the lender will require a gift letter stating it's not a loan. This is standard practice — tell your lender upfront.