Definition
The GDSR (Gross Debt Service Ratio) is the second key mortgage qualification ratio. It measures the share of your gross monthly income devoted solely to housing costs.
Formula: GDSR = (mortgage payment + property taxes + heating + 50% of condo fees) ÷ gross monthly income × 100.
Standard cap: 39% at most A lenders. On CMHC-insured loans, 39% is strict; on conventional loans, some lenders allow 42%. As with TDSR, the calculation uses the stressed qualifying rate for B-20 files. Note: a GDSR below 39% is not enough if TDSR exceeds 44% — both ratios must pass simultaneously. GDSR caps the "big debt-free loan"; TDSR caps the "loan with existing debts".