How the mortgage stress test actually works

The mortgage stress test is not a check of whether this month's payment fits. It is a check of whether the file still works if the rate used for qualification is higher than the rate written in the contract. Passing it means a lending rule was met. It does not mean the household will feel comfortable after closing.

What the test is actually asking

A federally regulated lender, such as a bank, has to test whether the borrower could keep paying if rates rose, income fell or household costs increased. The Financial Consumer Agency of Canada describes that requirement for both insured and uninsured mortgages. The test therefore applies to a minimum-down-payment purchase and to a conventional loan.

The lender calculates the payment at a qualifying rate, then compares that payment, plus property taxes, heating and other debts, with gross income. If the ratios exceed the limits in use, the requested amount is too high for the rule, even when the real payment looks manageable. A payment calculator and the stress test therefore answer different questions.

Lenders that are not federally regulated are not all bound to the same formula. The agency notes that they may still apply a stress test. Do not assume a credit union or an alternative lender will skip the step. Ask which rate and method that institution will actually use.

How the qualifying rate is chosen

Banks must use the higher of two figures: 5.25%, or the rate you negotiate with the lender plus 2%. That number is not an average and it is not the rate you would pay if the mortgage is funded. It is only the rate used to test capacity.

The 5.25% floor matters when the contract rate is low. If the contract were 3.00%, adding 2% would produce 5.00%, but the floor of 5.25% would win. Once the contract rate is above 3.25%, the contract-plus-2% figure usually governs. An illustrative contract of 4.50% would therefore be tested at 6.50%.

CMHC uses the same greater-of rule for the loans it insures, whether the rate is fixed, variable or adjustable. If a mortgage has more than one rate, each component has to be qualified.

That rate is not a forecast. It does not mean your payment will rise by 2% during the term. It creates a regulatory buffer. Your own budget may need a wider one, or it may already feel tight at the real payment.

How GDS and TDS turn a rate into a yes or no

The qualifying rate becomes a decision once it is turned into debt-service ratios. Gross debt service, or GDS, compares housing costs with gross income. Those costs include principal and interest, property tax, heating and half of any condo fees. The federal agency says those housing costs should not exceed 39% of gross household income.

Total debt service, or TDS, adds the rest of the monthly obligations: a car loan, credit cards, lines of credit, student loans or support payments. The same source puts that limit at 44% of gross income. A file can therefore clear GDS and still fail TDS if non-housing debts are heavy.

CMHC also explains how some debts are converted into a monthly figure. For a credit card or an unsecured line of credit, it uses at least 3% of the outstanding balance, not merely the minimum payment showing on the statement. A $4,000 card balance then counts as $120 a month. Borrowers who only send $80 often understate the number the lender will enter.

Taxes and heat matter. An estimate that is too low makes the ratios look better than they are; an estimate that is too high can fail a file that would pass with documented costs. Provide heating history if it exists.

The income in the formula is eligible gross income, not take-home pay. If the income the lender can use is lower than the cash you spend, the test tightens before the qualifying rate is applied.

A worked example, from contract rate to a fail

Suppose a household earns $108,000 a year before tax, or $9,000 a month. It is looking at a $500,000 property with a $100,000 down payment, so the loan is $400,000. The amortization is 25 years. Property tax is $300 a month and heat is $150. A car loan costs $380 and a credit card shows a $4,000 balance.

Use an illustrative contract rate of 4.50%. That is not an offer, only a number to show the mechanism. The real monthly payment, using ordinary Canadian compounding, would be about $2,214. Add tax and heat and actual housing costs would be about $2,664, or 29.6% of income.

The test uses 6.50%, the contract rate plus 2%. The qualifying payment then rises to about $2,679. Tested housing costs become $3,129, a GDS of about 34.8%. Add the car loan and 3% of the card balance and TDS is about 40.3%. Both ratios stay under 39% and 44%. The file meets the rule. The household still has to decide whether $2,214 plus the rest of homeownership is a payment it wants to carry.

If the down payment is smaller and the mortgage becomes $480,000, the contract payment would be about $2,657 and actual housing costs $3,107, or 34.5% of income. At the 6.50% qualifying rate, the tested payment would be about $3,215. GDS would rise to about 40.7%, above 39%. The file would fail even though the real payment remains under the housing-cost limit.

That gap is what many buyers discover too late: they compare the current payment with rent, and the lender compares a higher payment with a formula. A larger down payment can shrink the loan enough to change the result. Paying down revolving debt before the application can do the same on the TDS side.

When the test applies, and when a straight switch may not

On a new purchase, a refinance or a home equity line of credit, the federal agency says the stress test applies if you already have a mortgage and you are changing the shape of the debt. Staying with the same lender at renewal, without increasing the loan or the amortization, is generally not the same exercise as a newly underwritten mortgage.

Switching lenders at maturity used to be the move that most often brought the test back. Since December 2024, the Department of Finance Canada has removed the minimum-qualifying-rate requirement for certain low-ratio renewals that meet the tests of a straight switch. The mortgage must have been originated at a federally regulated institution and already assessed against the qualifying rate. The contractual amortization must be kept. Equity take-out is not allowed. The balance may rise by no more than $3,000 to cover transaction costs.

That exemption is not automatic and it does not cancel the rest of underwriting. The new lender still reviews the file. A refinance, a longer amortization or an equity withdrawal falls outside a straight switch. Our guide to the renewal letter explains why you should name the transaction before you compare offers. Published rules can also change, so reread the official pages before locking a purchase price to one calculation.

What the test leaves out, and what to check

Clearing the test says nothing about childcare, groceries, maintenance or a month of uneven income. A household can pass at 38% GDS and still feel stretched when one unexpected bill arrives. The reverse is also true. The rule protects the financial system and the lender. It does not replace your own comfort line.

The practical levers are purchase price, down payment, the amortization that is allowed, documented income and revolving debt. Buying a car just before an offer or leaving a large card balance can fail the file. Paying down a card or targeting a lower price can restore it. None of those steps promises an approval.

Before you shop, take the higher of 5.25% and the expected contract rate plus 2%. Estimate tax, heat and condo fees. Convert revolving balances the way the lender will. Compare GDS and TDS with 39% and 44%. Then compare the real payment, not only the tested payment, with the budget you still want to keep after you have the keys.

I match those figures to the documents in the file rather than to a quick estimate. The point is to see whether the target price fails because of the qualifying rate, a non-housing debt or income that is hard to support. You can start a prequalification to test those scenarios before an offer. A first conversation is free and does not commit you to a lender.

Certain conditions may apply. Subject to change without notice.