RatellowBeta
  • Ask AI
  • Guides
  • Scenarios
  • Blog

Ratellow © 2026

The intelligent hub for Canadian mortgage research.

Resources

  • Ask AI
  • Guides
  • Scenarios
  • FAQs
  • Blog
  • Glossary
  • Bookmarks

Analysis

  • All Calculators
  • Payment Calculator
  • Payment Comparison
  • Renewal Calculator
  • Renewal Comparison
  • Affordability Calculator
  • Land Transfer Tax

Rates

  • Mortgages Overview
  • All Mortgage Rates
  • 5-Year Fixed Rates
  • 3-Year Fixed Rates
  • 5-Year Variable Rates

Company

  • About Us
  • Support
TermsPrivacy

For informational purposes only. Not financial, legal, or professional advice. Consult a licensed mortgage professional before making decisions. See full disclaimer

FAQ Library
Purchasing•Verified 2026-02-18

How are debt service ratios calculated, and why are they important?

Key Points

  • Lenders use debt ratios to make sure you can comfortably afford your mortgage payments.

  • To check affordability, lenders use either your mortgage interest rate plus 2%, or 5.25%, whichever is higher.

  • Your property taxes and condo fees are included when the lender calculates how much you can afford.

  • Heating costs are factored into your affordability assessment, and these costs can vary depending on where you live.

Need a Deeper Breakdown?

Read the full research guide this FAQ was derived from for more context and strategy.

Technical Research Verification

Our systems synchronized 4 data points and regulatory frameworks to verify this technical brief.

Read the deeper guide · Purchasing

2026 Canada Closing Costs Guide: What Homebuyers Actually Pay at the Table

Related Questions

How does mortgage insurance enable lower down payments?

Mortgage insurance lowers the risk for lenders, allowing them to offer mortgages to borrowers with down payments between 5% and 20%.

How will lenders evaluate my debt service ratios, and what key factors are considered?

Lenders assess your ability to repay the mortgage by calculating your Gross Debt Service (GDS) and Total Debt Service (TDS) ratios.

What property considerations impact my mortgage application?

Lenders carefully assess the property's value and characteristics, directly influencing the loan amount you can secure.

How does the 'straight switch' exemption benefit you at renewal?

The 'straight switch' exemption lets uninsured mortgage borrowers move their mortgage to a new federally regulated lender (FRFI) at renewal without needing to pass the Minimum Qualifying Rate (MQR) .

Analyze Your Scenario

Calculator

Mortgage Payment Calculator

$2,147/mo
PrincipalInterest
Open Calculator

Today’s Lowest Mortgage Rates

5-Year Fixed
Lender 1
4.14%
3-Year Fixed
Lender 1
3.94%
5-Year Variable
Lender 1
3.49%
Prime Rate
Bank of Canada
4.45%

Debt service ratios, namely the Gross Debt Service Ratio (GDSR) and Total Debt Service Ratio (TDSR), are vital in gauging a borrower's ability to manage mortgage debt.

The GDS ratio measures the percentage of gross monthly income needed for housing costs, while the TDS ratio accounts for all debt obligations. Lenders stress-test mortgage affordability to ensure borrowers can manage rate fluctuations. Here's an example stress test: