How GDS and TDS Ratios Decide Your Loan Application in Canada

Canadian lenders reduce your finances to two ratios before they decide on a loan. The gross debt service ratio (GDS) measures how much of your income goes to housing costs, and the total debt service ratio (TDS) measures how much goes to housing plus every other debt payment you carry. Federally regulated mortgage lenders generally work to a total debt service ratio ceiling of about 44% and test the file at a qualifying rate above the contract rate, as set out in OSFI Guideline B-20. Unsecured lenders, including personal loan providers, set their own ceilings, and those ceilings are usually stricter because there is no property to recover if you default.

GDS: the housing-only ratio

GDS looks at one property and one household. The numerator is the monthly cost of carrying the home. The denominator is gross household income — income before tax, not the amount that lands in your bank account.

What goes into the numerator depends on the lender and the property type:

• Mortgage principal and interest. Where a mortgage is being arranged, lenders use the qualifying payment at the stress-test rate, not your contract rate.
• Property taxes for the year, converted to a monthly figure.
• Heating costs, usually taken from a lender's own estimate rather than your actual bills.
• Condominium or strata fees, in whole or in part, depending on the lender's policy.

One detail surprises people: Canadian fixed-rate mortgages are compounded semi-annually by law, which is why the qualifying payment a lender calculates can differ from a quick amortisation you run yourself. That calculated payment — not the promotional number — is what lands in the ratio.

TDS: the ratio that usually decides the file

TDS takes everything from GDS and adds every other regular debt payment you are obligated to make: credit card minimums, lines of credit, car loans and leases, instalment loans, student loan payments and court-ordered support. Two mechanical points matter more than most borrowers realise. First, lenders use the minimum payment on revolving credit, not the balance, which is why a card with a high balance but a low minimum can look harmless and still cost you an application. Second, the payment on any new loan is added to the numerator, so the interest rate on that loan changes your ratio even when the amount borrowed does not.

How to calculate your own ratios

1. Total the gross monthly income of every borrower on the application — employment income before deductions, plus any pension, rental, support or self-employment income the lender is willing to count.
2. Total the monthly housing costs for the property: the qualifying mortgage payment, property taxes, heating and any condominium fees the lender includes.
3. Total every other monthly debt payment: minimums on cards and lines of credit, instalment loans, leases, student loans and support obligations.
4. Divide housing costs by gross monthly income. That is your GDS.
5. Divide housing costs plus all other debt payments by gross monthly income. That is your TDS.
6. Compare the results against the ceilings the lender publishes — and remember that the lender will use its own qualifying rate rather than the rate you were quoted if a mortgage is involved.

What lenders treat as an acceptable ceiling

For residential mortgages, the published anchor is a total debt service ratio ceiling of about 44% at federally regulated lenders, applied together with a stress-test rate above the contract rate, per OSFI Guideline B-20. GDS ceilings are set lower than TDS ceilings, because a household spending too much of its income on housing alone is fragile before any other debt is counted.

That 44% figure is a mortgage underwriting benchmark, not a universal pass mark. Credit unions, provincially regulated lenders, finance companies and alternative lenders are not bound by B-20 and set their own limits. In unsecured lending the tolerance is typically lower and the assessment is broader: income stability, time in the current job, banking history, credit history and existing obligations all carry weight. The Financial Consumer Agency of Canada explains how personal loans work and what lenders must disclose, which is a sensible starting point before you compare offers.

Why a higher interest rate raises your ratio

Two applicants with the same income and the same existing debts can get opposite answers because the rate attached to the new loan is different. A higher rate means a larger monthly payment, which means a larger numerator in the TDS calculation, which means the ratio can cross the lender's ceiling on an identical amount borrowed. That is the practical link between credit history and debt ratios: credit history drives the price you are offered, and price drives the ratio the lender calculates. It is also why shopping for loans for not so good credit is harder than it looks — the offers that are easiest to qualify for tend to be the ones that stretch the ratio the most.

High-cost short-term credit behaves the same way. Where a province operates a licensed payday lending regime, federal regulations cap the cost of borrowing at $14 per $100 advanced, and provinces may set a lower cap; the lower figure applies. Quebec does not license payday lending at all, which effectively prohibits the model there. Even where those obligations never appear on a credit report, a lender reviewing bank statements can see them, and they compete with your new payment for the same income. For context on the outer limit of legal pricing in Canada, the Criminal Code sets the criminal rate of interest at 35% per year, calculated by a defined method that aggregates interest and certain charges.

Income you can prove versus income you earn

Ratios are built on documented income. A salaried borrower with a T4 is straightforward. Self-employed, contract, commission and gig income is usually averaged over a period or discounted to a proportion the lender chooses. Rental income is often counted only in part. Cash and tip income that cannot be documented generally cannot be used to lower your ratios, even when it is real and regular. If your file is borderline, the fastest fix is often not a different lender — it is documentation that lets the lender count income it would otherwise ignore.

Bringing the ratios down before you apply

• Attack revolving balances first. Reducing a card balance lowers the minimum payment, and the minimum payment is what sits in TDS.
• Do not open new credit in the months before an application. A new card or car loan adds a payment to the numerator and an inquiry to your file.
• Consolidate carefully. Combining several payments into one can lower the monthly figure, but compare total cost over the life of the loan, not just the payment.
• Add a co-borrower only after doing the arithmetic. Their income raises the denominator; their debts raise the numerator. The net effect is not always positive.
• Reduce the housing component. A smaller purchase price, a larger down payment, or a property with lower taxes or heating costs lowers GDS directly.
• Check your credit report. Canada has two national bureaus, Equifax Canada and TransUnion Canada, and each provides a free copy of your report. Errors are common and correctable, and the report is the source of the debt payments a lender will see.

When the ratio is not the deciding factor

Debt ratios are a filter, not a verdict. Credit history, employment stability, down payment or equity, property type and the lender's own risk appetite all carry weight. A history of insolvency does too: a consumer proposal stays on a credit report for three years after completion, or six years from filing, whichever comes first, and a first bankruptcy stays on a credit report for six years after discharge. Only a licensed insolvency trustee can administer a consumer proposal or a bankruptcy, and trustees are regulated by the Office of the Superintendent of Bankruptcy Canada.

If a lender's conduct concerns you, complaints about federally regulated financial institutions go to the Financial Consumer Agency of Canada, while provinces license and supervise most other lenders and each maintains a consumer protection office.

loanwolf.ca is a matching service, not a lender. It does not make loans, set rates or make credit decisions, and it cannot guarantee that any application will be approved. What it does is put your request in front of lenders whose criteria fit your file, so you can compare the cost of a personal loan or another form of credit side by side. The lowest rates advertised in any market are only ever available to the most qualified applicants — the strongest credit histories, the most stable documented income and the lowest existing debt loads. If your file falls outside that group, expect a higher rate, and expect that higher rate to raise the debt service ratio a lender calculates for you. For significant borrowing decisions, the arithmetic above is a starting point, not a substitute for regulated professional advice.