What is OSFI Guideline B-20?
By Nick Jang, founder of MINERVA Studio ·
The short answer
OSFI Guideline B-20, Residential Mortgage Underwriting Practices and Procedures, sets the underwriting standards for federally regulated lenders, in its current form since 31 October 2017. It is best known for the minimum qualifying rate, the mortgage stress test: an uninsured borrower must qualify at the greater of the contract rate plus 2 percentage points or 5.25%. Since fiscal 2025 OSFI has also capped, lender by lender, the share of new uninsured mortgages above 4.5 times the borrower’s income.
The five principles
B-20 applies to every federally regulated institution that underwrites or buys residential mortgages in Canada: loans to individuals secured by a one-to-four-unit home, home equity lines of credit (HELOCs) included.
| Principle | What it asks |
|---|---|
| 1. Governance | A written Residential Mortgage Underwriting Policy (RMUP), approved and followed. |
| 2. Identity and willingness | Know who the borrower is, their credit history and whether they pay on time. |
| 3. Capacity | Verify income and work out whether the borrower can service the debt, using debt service ratios. |
| 4. Collateral | Value the property soundly and manage it as collateral. |
| 5. Risk management | Run effective credit and counterparty risk management, including mortgage insurance where it applies. |
The stress test: the minimum qualifying rate
Most Canadians meet B-20 through one number. When a federally regulated lender approves an uninsured mortgage (usually 20% down or more), it checks the borrower can still pay at a higher rate than the one on the contract. That qualifying rate is the greater of:
- the mortgage contract rate plus 2 percentage points, or
- a floor of 5.25%.
So a borrower offered 4.39% is tested at 6.39%, and one offered 3.00% is tested at 5.25%. The floor has stood at 5.25% since June 2021, and OSFI reviews the calibration at least once a year. Insured mortgages are stress-tested too, under the federal government’s mortgage insurance rules rather than B-20.
There is one exemption worth knowing. Since 21 November 2024, a borrower who moves an existing stand-alone uninsured mortgage to another federally regulated lender at renewal, without adding to the amount or the amortization, doesn’t have to pass the stress test again. The new lender still underwrites the loan. Renewing with the same lender never required it.
Loan-to-value and loan-to-income limits
The revolving part of a HELOC can’t go above 65% of the home’s value. Above 80% loan-to-value, a purchase or renovation mortgage at a federally regulated lender must be insured by law, which is where the 20% down payment rule comes from.
The newer tool sits at the level of the lender, not the borrower. From the start of each institution’s fiscal 2025, OSFI set institution-specific limits on how much of each quarter’s new uninsured mortgage lending can go to loans above 4.5 times the borrower’s gross income. No single borrower is refused because of it; the lender has to keep the high-LTI share of its book under its own cap. OSFI said in January 2026 that the framework would continue.
What happens to B-20 next
On 29 January 2026 OSFI opened a consultation on a single Credit Risk Management guideline that would bring its scattered credit expectations into one document. A real estate secured lending chapter would carry the expectations now in B-20. The consultation closed on 29 July 2026, and OSFI plans to publish draft chapters in phases. Until a final guideline replaces it, B-20 and the qualifying rate apply as written.
Where models come in
Mortgage underwriting is full of models: income verification tools, automated valuation models, behavioural scores, the systems that read pay stubs. Each one is a model under E-23 from 1 May 2027, with an owner, a risk rating and a review, and the vendor-supplied ones are also B-10 arrangements. See what counts as a model.
Related questions
What is the OSFI mortgage stress test rate in 2026?
For uninsured mortgages at federally regulated lenders, the qualifying rate is the greater of the contract rate plus 2 percentage points or 5.25%. OSFI reviews it at least once a year.
Does B-20 apply to credit unions?
To federally regulated credit unions, yes. Provincially regulated credit unions follow their province’s rules, which may set a different qualifying rate.
Do I have to pass the stress test when I renew?
Not when renewing with the same lender, and since 21 November 2024 not when switching an uninsured mortgage to another federally regulated lender without increasing the amount or amortization.
What is the OSFI loan-to-income limit?
A cap, set separately for each lender, on the share of new uninsured mortgages above 4.5 times the borrower’s income. It applies to the lender’s portfolio, not to any single borrower.
Is B-20 being replaced?
OSFI consulted in 2026 on a consolidated Credit Risk Management guideline whose real estate chapter would carry B-20’s expectations. Until it is final, B-20 applies.
Sources
- OSFI — Guideline B-20, Residential Mortgage Underwriting Practices and Procedures (2017)
- OSFI — Minimum qualifying rate for uninsured mortgages
- OSFI — Loan-to-income limits for uninsured mortgage portfolios
- OSFI — Exempting uninsured straight switches from the MQR and implementing portfolio LTI limits (21 November 2024)
- OSFI — Backgrounder: Consultative document on Credit Risk Management (29 January 2026)
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A plain-language explanation, not legal advice. The regulator’s own text is the source; read it, and take advice on how it applies to your institution.