Glossary
Mortgage Underwriting
The lender's review of your income, credit, down payment, and the property's value before it approves or declines your mortgage..
Mortgage underwriting is the lender's assessment of your application and the property before approving a mortgage. An underwriter reviews your income, credit history, down payment, debts, and the home's appraised value, then decides whether the file meets the lender's criteria and any default insurance requirements.
What an underwriter actually checks
Underwriting is a verification exercise, not a sales step. A mortgage agent or broker may gather your paperwork, but the underwriter is the person who decides. Typical checks include:
- Income — pay stubs, letters of employment, CRA notices of assessment, or business financials for self-employed borrowers, all part of income verification.
- Credit — your credit score and report, including collections, judgements, or missed payments.
- Capacity — GDS and TDS ratios, which compare housing costs and total debt payments to gross income.
- Down payment — the source and seasoning of funds; borrowed down payments face extra scrutiny.
- Property — an appraisal or automated valuation confirming the home supports the loan amount and the loan-to-value ratio.
Why the rules are stricter than they look
Federally regulated lenders follow OSFI Guideline B-20, and high-ratio loans, meaning a down payment under 20%, generally require mortgage default insurance from CMHC, Sagen, or Canada Guaranty. That is why the mortgage stress test applies: you must qualify at a higher rate than the contract rate, so the lender is satisfied you could keep paying if rates rise. Insurers and lenders also cap how much of your income can go to housing costs and total debt.
What it means for you
Underwriting usually happens after you have a signed agreement of purchase and sale and a pre-approval, and it can take days to weeks depending on how complete your documents are. A conditional offer typically protects you with a financing condition until the lender issues a firm commitment.
Common reasons files stall: unexplained deposits, recently changed income, a new car loan taken out mid-application, or an appraisal that comes in below the purchase price. Submitting complete documents early shortens the process. Standards vary by lender — banks, credit unions, monolines, and private lenders each apply their own criteria, so a decline from one does not guarantee a decline elsewhere.
Frequently asked questions
How long does mortgage underwriting take in Canada?
Many files are reviewed within a few business days once all documents are received, but complex cases can take two weeks or longer. Missing paperwork, self-employment income, or a property appraisal that needs a second look all add time. Ask your lender or broker what is outstanding, and respond to requests quickly to avoid delays.
What can cause a mortgage to be declined during underwriting?
Typical reasons include income that cannot be documented, a debt service ratio above the lender's limit, damaged credit, insufficient or borrowed down payment, or an appraisal below the purchase price. A property that fails insurer criteria, such as certain non-standard construction, can also be refused. Each lender weighs these factors differently.
Does underwriting happen before or after pre-approval?
Pre-approval is a preliminary look at your finances and usually involves little or no property review. Full underwriting comes later, once you have an accepted offer on a specific home, and it confirms income, down payment, and the property's value. A pre-approval is not a guarantee that the final mortgage will be approved.
Sources
Related terms
- Mortgage Stress Test — The federal mortgage stress test is a qualification rule that makes lenders check whether you could afford your mortgage if rates were higher than your contract rate.
- Gross Debt Service Ratio (GDS) — The share of gross household income that goes to housing costs — mortgage principal and interest, property taxes, heating, and half of condo fees — commonly capped at 39%.
- Total Debt Service Ratio (TDS) — The Total Debt Service Ratio (TDS) is the share of gross income that goes toward all debt payments, capped at 44% by most Canadian lenders.
- Income Verification — The process a lender uses to confirm the income stated on a mortgage application, using documents such as pay stubs, tax slips, and CRA notices.
- Mortgage Pre-Approval — A mortgage pre-approval is a lender's conditional commitment to lend a set amount at a held rate, subject to verifying your income, debts and the property.