What is a debt-to-income ratio?
**A debt-to-income (DTI) ratio measures how much of your gross monthly income goes toward debt payments.** In Canada, mortgage lenders use two specific DTI ratios to assess whether you can afford a mortgage: the Gross Debt Service (GDS) ratio and the Total Debt Service (TDS) ratio.
The GDS ratio looks only at housing costs: your mortgage payment (or rent), property taxes, heating costs, and 50% of any condo fees, divided by your gross monthly income. The TDS ratio adds all other debt obligations on top of housing costs: car loans, student loans, credit card minimum payments, and any other recurring debt.
These ratios are a core part of the mortgage underwriting process in Canada. Every federally regulated lender must check them as part of the OSFI B-20 guidelines. If your ratios exceed the maximum thresholds, you will not qualify for an insured mortgage, and many conventional lenders will decline your application as well.
Unlike the United States, which uses a single back-end DTI ratio, Canada separates housing debt (GDS) from total debt (TDS). This two-ratio system gives lenders a more granular view of your financial obligations and helps identify whether the risk comes from housing costs, consumer debt, or both.
GDS vs TDS: what Canadian lenders calculate
**The GDS ratio measures housing affordability. The TDS ratio measures total debt burden.** Both must fall within lender limits to qualify for a mortgage in Canada.
GDS = (Mortgage payment + Property taxes + Heating costs + 50% of condo fees) / Gross monthly income. This ratio tells lenders whether your housing costs alone are sustainable relative to your income. The standard maximum is 39% for insured mortgages (CMHC, Sagen, Canada Guaranty).
TDS = (All housing costs + Car loan + Student loan + Credit card minimums + Other debts) / Gross monthly income. This broader ratio captures your entire debt picture. The standard maximum is 44% for insured mortgages.
Some conventional lenders use stricter limits: GDS of 35% and TDS of 42%. Credit unions and alternative lenders may be more flexible, sometimes accepting GDS up to 45% or TDS up to 50% for borrowers with strong compensating factors like high net worth or excellent credit scores above 720.
| Ratio | Formula | Insured max | Some lenders |
|---|---|---|---|
| GDS | Housing costs / Gross income | 39% | 35% |
| TDS | All debts / Gross income | 44% | 42% |
Canadian mortgage qualification thresholds
**The thresholds vary depending on whether the mortgage is insured or conventional, and each lender may apply its own risk tolerance within regulatory limits.**
For insured mortgages (down payment less than 20%), CMHC, Sagen, and Canada Guaranty all require GDS of 39% or less and TDS of 44% or less. These are hard limits with very few exceptions. The mortgage insurer must approve the application before the lender can fund it.
For conventional mortgages (down payment of 20% or more), OSFI B-20 guidelines apply to federally regulated banks but allow some flexibility. Most major banks target GDS of 35% to 39% and TDS of 42% to 44%. Some allow exceptions for borrowers with beacon scores above 680 and strong compensating factors.
Credit unions are provincially regulated and not bound by OSFI B-20, though many voluntarily follow similar guidelines. Private lenders and mortgage investment corporations (MICs) may not use GDS/TDS at all, instead focusing on the loan-to-value ratio and the property's equity.
Importantly, lenders calculate these ratios using the stress test qualifying rate (your contract rate + 2%, or 5.25%, whichever is higher), not your actual mortgage rate. This means your qualifying GDS and TDS will be higher than your actual ratios at the contract rate.
How to improve your debt-to-income ratio
**There are two paths to improving your DTI ratios: reduce your debts or increase your income.** The fastest improvements usually come from eliminating high-payment consumer debts.
Pay down credit card balances first. Credit card minimum payments are pure overhead in the TDS calculation. If you carry a $5,000 balance with a $150 minimum payment, paying it off removes $150 from your TDS numerator instantly. This can improve your TDS ratio by 2 to 3 percentage points on a $6,000 monthly income.
Pay off or refinance your car loan. Car payments are often the largest non-housing debt. If you are 12 months from paying off a $400/month car loan, waiting to apply for a mortgage until it is paid off can drop your TDS by over 5 percentage points.
Increase your qualifying income by adding a co-borrower. Dual-income applications dramatically reduce both GDS and TDS ratios. If your partner earns $4,000 per month and you earn $6,000, adding them to the application increases your denominator from $6,000 to $10,000.
Reduce your target home price. A smaller mortgage means lower housing costs, which directly reduces both GDS and TDS. If you are 2% over the GDS limit, reducing your purchase price by $30,000 to $40,000 may be enough to qualify.
Consolidate high-interest debts. Replacing multiple credit card payments with a single consolidation loan at a lower rate can reduce your total monthly debt payments while keeping the same balance. This improves TDS without changing how much you owe.
- ✓Pay off credit card balances to eliminate minimum payment obligations
- ✓Wait until a car loan is paid off before applying for a mortgage
- ✓Add a co-borrower to increase qualifying household income
- ✓Reduce your target home price to lower the required mortgage amount
- ✓Consolidate debts to reduce total monthly payment obligations
- ✓Avoid taking on new debt in the 6 months before a mortgage application
What lenders look at beyond GDS and TDS
**GDS and TDS are necessary but not sufficient for mortgage approval.** Lenders evaluate several additional factors as part of a complete underwriting assessment.
Your credit score (beacon score) is the first filter. Most A-lenders require a minimum of 620 to 680. A higher score gives you access to better rates and may allow some lender flexibility on DTI ratios. Scores below 600 typically push borrowers to B-lenders or private lenders.
Employment stability and income type matter significantly. Salaried employees with 2+ years at the same employer are easiest to qualify. Self-employed borrowers must typically provide 2 years of Notice of Assessment from the CRA, and lenders may average the two years or use the lower figure.
Down payment source and size affect risk assessment. Lenders want to see that your down payment comes from savings, investments, or a gifted amount from an immediate family member. Borrowed down payments increase your debt ratios and are a red flag.
The property itself must appraise at or above the purchase price. The lender orders an independent appraisal to confirm the property's market value. If the appraisal comes in low, the lender reduces the mortgage amount, requiring a larger down payment.
Finally, lenders look at your overall debt profile, including debts not captured in the TDS calculation like cell phone plans, insurance premiums, and childcare costs. While these are not part of the formal ratio, an underwriter may flag them if they create excessive financial strain.
How to use the debt-to-income ratio calculator
**Enter your gross monthly income first.** This is your total household income before any deductions. If you are paid biweekly, multiply your gross pay by 26 and divide by 12 to get the monthly equivalent.
**Add your housing costs.** Enter your monthly mortgage or rent payment, property taxes (divide your annual tax bill by 12), estimated heating costs, and condo fees if applicable. The calculator automatically applies the 50% rule for condo fees, matching how lenders calculate GDS.
**Enter your other debt payments.** Add each category: car loan payment, student loan payment, credit card minimum payments (add up all cards), and any other recurring debt like personal loans or lines of credit. Only include mandatory monthly payments, not discretionary spending.
**Review the results.** The GDS and TDS gauge bars show your ratios colour-coded: green (pass all lender thresholds), yellow (pass insured limits but tight for some lenders), or red (exceeds standard limits). The donut chart shows how your debt is distributed across categories.
**Model different scenarios.** Adjust any input to see how paying off a debt or increasing your income changes your ratios. If you are 3% over the TDS limit, try setting your credit card minimum to zero to see if eliminating that debt would get you below the threshold.
Frequently asked questions
What is a good debt-to-income ratio in Canada?
For mortgage qualification in Canada, your GDS ratio should be 39% or less and your TDS ratio should be 44% or less. Some lenders prefer even lower ratios: GDS of 35% and TDS of 42%. A GDS below 30% and TDS below 36% are considered excellent and give you the most flexibility when shopping for mortgage rates.
What is the difference between GDS and TDS?
GDS (Gross Debt Service) includes only housing costs: mortgage payment, property taxes, heating, and 50% of condo fees. TDS (Total Debt Service) includes all of those housing costs plus all other debt payments: car loans, student loans, credit card minimums, and other obligations. Both ratios use your gross monthly income as the denominator.
Can I get a mortgage if my TDS is over 44%?
It is difficult but not impossible. Insured mortgages through CMHC, Sagen, or Canada Guaranty require TDS of 44% or less with very limited exceptions. Some credit unions and alternative lenders accept higher ratios if you have strong compensating factors like excellent credit, significant savings, or a large down payment. Private lenders may not use TDS at all but charge significantly higher rates.
Does rent count in the GDS ratio?
If you are a renter and applying for a mortgage, the GDS calculation uses the proposed mortgage payment, not your current rent. If you are calculating your DTI to assess your current financial health, you can enter your rent in the mortgage/rent field to see what percentage of your income goes to housing.
Are condo fees fully included in GDS?
No. Canadian lenders include only 50% of monthly condo fees in the GDS calculation. The rationale is that a portion of condo fees covers building maintenance and reserves rather than being a true housing expense. This calculator automatically applies the 50% rule.
Do lenders use the stress test rate for GDS and TDS?
Yes. Under OSFI B-20 guidelines, federally regulated lenders must calculate GDS and TDS using the qualifying rate, which is the higher of your contract rate plus 2% or 5.25%. This means your qualifying ratios will be higher than your actual ratios at the contract rate. This calculator shows your ratios based on the payments you enter, so use your stressed mortgage payment if you want to see what lenders see.
What debts are included in the TDS calculation?
TDS includes all minimum mandatory monthly debt payments: mortgage (or rent), property taxes, heating costs, 50% of condo fees, car loans, student loans, credit card minimum payments, personal loans, lines of credit, child support, alimony, and any other court-ordered or contractual debt obligations.
How quickly can I improve my debt-to-income ratio?
The fastest way to improve your DTI is to pay off a consumer debt entirely. Eliminating a $300/month car payment instantly reduces your TDS by 4 to 5 percentage points on a $7,000 monthly income. Increasing income also helps but takes longer. Adding a co-borrower to a mortgage application can improve ratios immediately by increasing the income denominator.
Does a line of credit count toward TDS?
Yes. Most lenders calculate the line of credit payment as 3% of the outstanding balance per month, regardless of your actual minimum payment. For example, a $20,000 line of credit balance would add $600/month to your TDS numerator, even if your actual minimum payment is much lower.
Is DTI the same in Canada and the US?
No. The US uses a single back-end DTI ratio (all debts divided by gross income) with a typical maximum of 43% to 50% depending on the loan type. Canada uses two separate ratios: GDS for housing costs and TDS for total debts. The Canadian system also requires the stress test qualifying rate, which the US does not have. The two-ratio approach gives Canadian lenders a more detailed view of where your debt burden lies.