The OSFI B-20 stress test requires federally regulated lenders to qualify uninsured mortgage borrowers at the higher of the contract rate plus 2 percentage points or the 5.25% benchmark rate. Insured borrowers (less than 20% down) face the same qualifying rule. The stress test does not change the actual rate paid; it determines the maximum mortgage that can be approved given the borrower’s income and debt servicing ratios.
The qualifying rate
Borrowers must demonstrate they can afford the mortgage at the qualifying rate, calculated as: max(contract rate + 2%, 5.25%). At a contract rate of 4.50%, the qualifying rate is 6.50% (contract + 2%). At a contract rate of 3.00%, the qualifying rate is 5.25% (the floor). The qualifying rate is used only for ratio testing; the borrower still pays the contract rate.
Where the stress test applies
| Loan type | Stress test applies? |
|---|---|
| Insured mortgage (less than 20% down) | Yes — using max(contract+2%, 5.25%) |
| Uninsured mortgage at federally regulated lender | Yes — same formula |
| Renewal at the same federally regulated lender | Generally exempt for straight renewals (no new money or term change); some lenders apply it anyway |
| Switch to a new federally regulated lender at renewal | Yes — historically applied; OSFI has signaled this may be reformed |
| Provincial credit union or private lender | Not federally regulated, so not subject to B-20 directly |
Worked example
A borrower with $120,000 gross household income, no other debt, applying for a 25-year amortization on a $600,000 home with 20% down ($480,000 mortgage) at a 4.75% contract rate.
- Qualifying rate: max(4.75% + 2%, 5.25%) = 6.75%
- Qualifying payment at 6.75%, 25-year amortization, $480,000: approximately $3,302/month
- Property tax estimate: $400/month. Heating: $150/month. Total housing cost for ratio: $3,852/month
- Gross Debt Service (GDS) ratio: $3,852 / ($120,000 / 12) = 38.5%, just under the 39% limit
The borrower passes. At a higher contract rate or with other debt, GDS would exceed 39% and the lender would deny or reduce the loan.
GDS and TDS ratios
The stress test feeds into two debt-service ratios that determine maximum loan size:
- GDS (Gross Debt Service): Housing costs (mortgage P&I at qualifying rate, property tax, heat, half of strata/condo fees) divided by gross household income. Insured limit: 39%.
- TDS (Total Debt Service): GDS plus all other debt payments (credit cards, lines of credit, car loans, student loans). Insured limit: 44%.
Both ratios must be within limits for the loan to be approved. A borrower with high other debts may be GDS-eligible but TDS-disqualified.
Why the stress test exists
The stress test was introduced in 2018 in response to rapid home price increases and rising household debt. The Office of the Superintendent of Financial Institutions (OSFI) updated B-20 to ensure mortgage borrowers can afford payments if interest rates rise. The 2% buffer over the contract rate represents a plausible rate-rise scenario over the term of the mortgage.
Strategies to qualify for a larger mortgage
- Reduce other debt (pay down lines of credit, credit cards) to lower TDS.
- Increase down payment past 20% to reduce mortgage size.
- Extend amortization to 30 years if eligible (first-time buyers, new construction). 30-year amortization has lower monthly payment, which lowers GDS.
- Co-borrowers to add their income to the household.
- Consider a credit union or non-federally-regulated lender if the bank denies. Rates are typically higher.
Renewal considerations
Borrowers renewing with the same federally regulated lender are generally exempt from the stress test on a straight renewal (same loan amount, same amortization, no extension). Switching to a different federally regulated lender at renewal has historically required passing the stress test again. OSFI has signaled potential reform of this rule, but as of writing it remains in effect.
Frequently asked questions
- What is the OSFI B-20 stress test rate?
- The qualifying rate is max(contract rate + 2 percentage points, 5.25%). At a 4.50% contract rate, the qualifying rate is 6.50%.
- Does the stress test apply to renewals?
- Straight renewals at the same federally regulated lender are generally exempt. Switching lenders at renewal has historically triggered the stress test.
- What are GDS and TDS ratios?
- GDS is housing costs divided by gross income (limit 39% insured). TDS is GDS plus all other debt payments (limit 44% insured).
- Does the stress test apply to credit unions?
- Provincially regulated credit unions are not subject to OSFI B-20 directly. Many adopt similar standards voluntarily but specific rules vary by institution.
- Does the stress test affect my actual payment?
- No. The stress test only determines whether you qualify. You still pay the actual contract rate, not the higher qualifying rate.
- Can I extend amortization to pass the stress test?
- Yes, if eligible. First-time buyers and new construction can use 30-year amortization, which lowers monthly payment and improves GDS ratio.
- Why was the stress test introduced?
- OSFI introduced the B-20 stress test in 2018 to ensure borrowers can absorb interest rate increases. The 2 percentage point buffer represents a plausible rate-rise scenario over the term.