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GDS and TDS Ratios for Canadian Mortgages: Limits, What Counts and Calculator (2026)

Updated

Lenders use two ratios to decide whether you can carry a mortgage: how much of your income goes to housing, and how much goes to all your debts. This page explains both, CMHC’s limits and what counts, and the calculator below works out your own.

Annual Gross Income
Monthly Mortgage Payment
Monthly Property Tax
Monthly Heating Costs
Condo Fees (50%)
Monthly Debt Payments
Gross Debt Service (GDS) Ratio
Monthly Gross Income
Housing Costs (PITH)
GDS Ratio
GDS Limit (39%)
Total Debt Payments
TDS Ratio
TDS Limit (44%)
Qualification

Gross debt service (GDS)

GDS is your monthly housing costs divided by your gross monthly household income. CMHC counts:

  • the mortgage payment, principal and interest, worked out at the qualifying rate
  • property taxes
  • heating
  • 50% of any condominium fees
For an insured mortgage, CMHC caps your housing costs at 39% of gross income (GDS) and your housing costs plus other debt payments at 44% (TDS); lenders set their own limits for uninsured mortgages.

Total debt service (TDS)

TDS adds your other debt payments to the housing costs: car loans, student loans, and credit card and line of credit payments. For an insured mortgage it can be at most 44%. With no other debts, GDS is the harder limit to meet; once other debts are large enough, TDS takes over.

The rate used

The mortgage payment in both ratios is worked out at the stress-test qualifying rate, not your contract rate: You qualify at the greater of your contract rate plus 2% or 5.25%. So the ratios lenders see are higher than your real payment would suggest. The stress test calculator shows the difference.

Worked example

Take a $500,000 home bought with the minimum down payment. At the qualifying rate of 6.05%, the mortgage payment is $3,175 a month. With property tax of $417 and heating of $150 (this site’s assumptions), housing costs come to $3,742. To keep that at 39% of income, the household needs about $9,595 a month, or $115,100 a year.

Add $1,000 a month of car and credit payments and TDS decides instead: the income needed rises to about $129,300.

Uninsured mortgages

CMHC’s limits apply to mortgages it insures. For uninsured mortgages, with 20% or more down, OSFI’s Guideline B-20 requires federally regulated lenders to set their own debt serviceability measures, and they still have to qualify you at the stress-test rate.

Sources

The figures and rules on this page come from these sources, last checked against them between September 25, 2026 and October 2, 2026. How we check facts.