Key takeaways
- →The stress test requires borrowers to qualify at a minimum qualifying rate (MQR) — the greater of their contract rate plus 2%, or 5.25% — per OSFI Guideline B-20.
- →Insured mortgages have always required MQR qualification. For uninsured straight switches, OSFI removed that requirement effective November 21, 2024, as long as the loan amount and amortization don't increase.
- →Lenders still apply some debt-service check on switches under B-20's general principles — the change removed a specific requalification hurdle, not underwriting judgment altogether.
- →Naming both numbers — the rate a client pays and the rate their file qualifies at — up front heads off the single most common confusion in a pre-approval conversation.
Every Canadian mortgage — insured or not — gets measured against a number the client never actually pays: the minimum qualifying rate. It's the single biggest lever on how much a borrower qualifies for, and it's also the part of the file clients understand the least.
The rules changed in a meaningful way in late 2024, and the details matter for how you frame a renewal or a switch conversation today. This is the working reference: what the MQR formula is, how it splits between insured and uninsured files, what actually changed for switches, and a worked example you can walk a client through.
01 · What is the minimum qualifying rate, and where does it come from?
The minimum qualifying rate (MQR) is the rate a borrower must qualify at — not the rate they'll actually pay. It exists so that a borrower who takes a mortgage today can still absorb higher payments if rates rise before their term is up.
The MQR is set out in OSFI Guideline B-20, and it's calculated as the greater of the borrower's contract rate plus 2 percentage points, or 5.25%, per OSFI's B-20 infosheet. Whichever number is higher is the one a lender qualifies the file against — see our fuller walk-through of how mortgage underwriting works in Canada for where this fits in the full review.
02 · Does the stress test apply the same way to insured and uninsured mortgages?
Not quite, and the gap has widened since 2024. Insured mortgages — those with a down payment below 20%, backed by CMHC, Sagen, or Canada Guaranty — have always required MQR qualification, with no carve-out for switches or renewals.
Uninsured mortgages — 20% down or more — used to require the same MQR requalification from federally regulated lenders, including when a borrower switched lenders at renewal. That's the piece that changed. See Insured vs. Uninsured Underwriting for the rest of what shifts at the 20%-down line.
03 · What changed for uninsured mortgage switches in late 2024?
Effective November 21, 2024, OSFI removed the MQR requirement for straight switches of uninsured mortgages — moving an existing mortgage to a new federally regulated lender without increasing the loan amount or extending the amortization — per Canadian Mortgage Trends' reporting on the change.
What counts as a straight switch: Moving a mortgage from one federally regulated lender to another at the same loan amount and the same amortization — no increase to either. Add even a modest top-up and the file is back to full MQR qualification.
That doesn't mean switches go unexamined. OSFI's own comments alongside the change made clear that lenders are still expected to apply some form of debt-service stress test under B-20's general principles — the specific MQR requirement was removed for this one scenario, not underwriting judgment generally. A missed switch-vs-refinance distinction is one of the more common reasons a file stalls at this stage; see our companion piece on why mortgage files get declined in Canada for the fuller list.
Fewer surprises at the stress-tested number
Package every file against the right qualifying rate.
Treadstone's fulfillment associates run the MQR math on every file before submission. Or, if you'd rather run that check yourself, join the early-access waitlist for Engage's AI mortgage underwriting.
04 · How does the MQR formula work on an actual file?
Here's the arithmetic on an illustrative insured file, applying the formula above:
| Input | Value |
|---|---|
| Gross annual household income | $95,000 |
| Contract rate offered (5-year fixed) | 4.79% |
| MQR floor | 5.25% |
| Contract rate + 2% | 6.79% |
| Qualifying rate applied (greater of the two) | 6.79% |
The borrower shops at 4.79%, but the lender qualifies the file at 6.79% — the higher of the two numbers under the B-20 formula. That 200-basis-point gap is what determines how much mortgage the income can actually support, not the rate printed on the commitment letter. Run the identical math against a lower contract rate and the gap narrows, but the 5.25% floor never disappears — it's the reason a stress-tested pre-approval rarely moves much even when contract rates fall.
05 · How should brokers explain the stress test in a client conversation?
Name both numbers early and explicitly: the rate they'll pay, and the rate the file qualifies at. Clients who hear only the first number and then receive a smaller pre-approval than expected assume something went wrong with their application, when the math is standard and every Canadian borrower faces the same formula.
For the ratio math the qualifying rate feeds into, walk clients through three Canadian files run by hand, and keep a repeatable version of this calculation on file with the Stress Test Calculation Worksheet. Running these two numbers consistently, on every file, before it reaches a lender, is exactly the kind of check an early-access tool like Treadstone's AI mortgage underwriting is built to run automatically.
Frequently asked questions
This article is general information to help you scale — not a substitute for tailored advice on your specific business, licensing, or compliance obligations. All figures are illustrative examples for planning purposes; actual costs vary by province, market, and brokerage.