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Canadian GDS/TDS calculator — with the stress test

Debt-service ratios the way underwriters actually run them: P+I priced at the minimum qualifying rate with semi-annual compounding, checked against the 39%/44% insured guidelines. Know whether a file qualifies while the client is still on the phone.

GDS ratio

29.5%

within 39% guideline

TDS ratio

34.3%

within 44% guideline

Qualifying rate

6.50%

higher of contract + 2 pts and the 5.25% floor

Stress-tested P+I payment

$2,947.22

vs $2,435.28 at the contract rate

Room under the 44% TDS guideline: about $1,136/month of additional debt service.

Uses Canadian semi-annual compounding and the 39%/44% commonly applied insured guidelines — lender and insurer discretion varies, and the qualifying-rate floor is reviewed periodically. Estimates for discussion, not a qualification decision.

What is the GDS ratio?

The Gross Debt Service ratio measures housing costs against gross income. The numerator is the “PITH” basket — the mortgage Principal and Interest payment (at the qualifying rate, not the contract rate), property Taxes, and Heating — plus 50% of condo fees where applicable, divided by gross monthly income. The commonly applied insured guideline caps GDS at 39%.

What is the TDS ratio?

The Total Debt Service ratio takes the entire GDS numerator and adds every other monthly obligation: car loans and leases, credit card and line-of-credit payments (typically 3% of revolving balances), student loans, support payments, and co-signed debts. The commonly applied insured guideline caps TDS at 44%. A client can pass GDS comfortably and still fail on TDS — a $700 truck payment moves TDS by several points on a typical income.

What rate does the stress test use?

Both ratios price the mortgage payment at the minimum qualifying rate: the higher of the contract rate plus 2 percentage points and the regulatory floor (5.25% when the current framework was introduced). The floor is reviewed periodically — verify the current value against OSFI's published minimum qualifying rate before quoting. A client offered 4.5% is therefore qualified as if they were paying 6.5% — which is why the stress-tested payment above is the one that decides the file.

Are 39% and 44% hard limits?

No — they are the commonly applied guidelines for insured mortgages (CMHC and the private insurers), and they are where most files are underwritten. Conventional lenders have discretion, some products allow higher ratios with compensating factors, and credit unions and alternative lenders run their own boxes. Treat this calculator as the mainstream case, and the full walkthrough — what counts in each basket, with the worked example these defaults come from — is in our GDS and TDS guide for Canadian brokers.

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Estimates for professional discussion, not a qualification decision or advice. Guidelines and the qualifying-rate floor change — verify current OSFI, CMHC, and lender criteria before relying on any number here. Inside BrokerOS, these ratios are calculated on the live client file and re-run as the file changes.