Glossary
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%..
Gross Debt Service Ratio (GDS) is the share of your gross household income that goes toward housing costs. Lenders express it as a percentage and compare the result against a maximum — commonly 39% — when deciding whether a mortgage payment fits your budget. Gross income means income before tax and other deductions.
What goes into the GDS calculation
GDS adds up the housing costs tied to the property you want to buy, then divides them by your gross annual income:
- Mortgage principal and interest on the new loan, using the lender's qualifying payment rather than the payment you would actually make
- Property taxes, usually the annual municipal bill
- Heating costs, often entered as a standard estimate rather than your own bills
- Half of monthly condo or strata fees, where the home is a condo or strata unit
Because of the federal mortgage stress test, most federally regulated lenders qualify you at a rate higher than your contract rate, which raises the mortgage payment used in GDS. Confirm the current minimum qualifying rate with your lender or on the OSFI and Department of Finance websites.
GDS versus TDS, and the 39% guideline
GDS covers housing costs only. The Total Debt Service Ratio (TDS) adds your other debts — car loans, credit cards, student loans, lines of credit — on top, and most lenders cap it near 44%. Both figures belong to the same debt service ratio family used in underwriting. Insurers such as CMHC, Sagen and Canada Guaranty may allow some flexibility for borrowers with strong credit, savings or other compensating factors.
Why GDS matters to borrowers
Your GDS is one of the first numbers an underwriter reviews, and it often sets the ceiling on how much you can borrow — more so than your down payment alone. If a lender or insurer grants an exception, it comes with conditions attached.
Suppose a household earns $100,000 a year, or roughly $8,333 a month. A 39% GDS allows about $3,250 a month for housing. If property taxes and heating take $450 of that, roughly $2,800 remains for the qualifying mortgage payment. These figures are illustrative only. A larger down payment, fewer debts or a co-signer can change the outcome, but none of that guarantees approval. A mortgage affordability calculator can show how the numbers move.
Frequently asked questions
What is a good GDS ratio in Canada?
Many Canadian lenders treat 39% as the general maximum for GDS on a new mortgage, while TDS is often capped near 44%. Lower is better, because it leaves room if rates rise or your expenses change. Insurers may consider higher ratios when a borrower has strong credit and savings, so ask your lender which limits apply to your file.
Does GDS include property taxes and heating?
Yes. GDS adds mortgage principal and interest, property taxes, heating costs and half of any condo or strata fees, then divides the total by gross household income. Other debts such as car loans and credit cards are left out of GDS but are included in the Total Debt Service Ratio instead.
Can I get a mortgage if my GDS is too high?
Possible steps include paying down debts, increasing your down payment, adding a co-signer with income, or considering a less expensive property. Some borrowers ask about an exception through a lender or insurer. None of these guarantees approval. Shrinking the qualifying mortgage payment usually affects the ratio the most.
Sources
Related terms
- 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.
- Debt Service Ratio — A measure comparing your housing and other debt payments with your income, used by Canadian lenders when deciding whether you qualify for a mortgage.
- 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.
- Exception — An exception is a lender’s case-by-case allowance for a strong applicant to exceed a standard mortgage qualification rule.
- 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.