Refinance•By Ratellow Research Team•Verified 2026-02-18

2026 Canadian Mortgage Refinance Guide: Break-Even Calculator, OSFI B-20 Rules & CMHC Limits

Q: How do GDS and TDS ratios affect my refinancing options?

GDS (Gross Debt Service) and TDS (Total Debt Service) ratios are critical affordability indicators that financial institutions use to determine your eligibility for refinancing. They represent the percentage of your gross income required to cover housing costs and other debts. ### GDS/TDS Formula > **GDS** = (Principal + Interest + Taxes + Heat + 50% Condo Fees) / Gross Income > **TDS** = (PITH + Other Debts) / Gross Income ### Calculation Breakdown: $500k Refinance Scenario Consider a household with **$100,000 gross annual income** ($8,333/mo) refinancing into a $500,000 mortgage at 4.5% interest: | Component | Monthly Amount | Notes | |---|---|---| | Principal & Interest | $2,763 | Based on 4.5% over 25 years | | Property Taxes | $333 | Estimated $4,000 annually | | Heating Costs | $100 | Standard estimate | | **Housing Total (PITH)** | **$3,196** | Total core housing costs | | Other Debts (Car, Credit) | $500 | Assumed external obligations | | **Total Debt Load** | **$3,696** | Total monthly obligations | **Resulting Ratios:** - **GDS: 38.4%** ($3,196 / $8,333) — *Pass (Threshold ≤ 39%)* - **TDS: 44.4%** ($3,696 / $8,333) — *Fail (Threshold ≤ 44.0%)* In this scenario, while the housing costs (GDS) are within limits, the total debt (TDS) slightly exceeds the allowance, requiring either a lower loan amount or debt reduction to qualify.

Q: What is the Loan-to-Value (LTV) ratio, and how does it impact my ability to refinance?

The Loan-to-Value (LTV) ratio plays a critical role in the refinancing process. It's calculated by dividing the mortgage amount by the property's appraised value, and it essentially represents the amount of equity you have in your home. Generally, a lower LTV (indicating more equity) translates to more favorable refinancing terms. OSFI mandates that FRFIs maintain dynamic LTV ratio frameworks. The LTV is recalculated whenever you refinance and at any other time it's deemed prudent, considering shifts in a borrower's risk profile or delinquency status, using a suitable valuation or appraisal method.

Q: How does OSFI's Guideline B-20 affect refinancing?

OSFI's Guideline B-20 establishes the benchmark for residential mortgage underwriting practices that federally regulated financial institutions (FRFIs) must adhere to. This guideline directly influences how lenders evaluate borrower risk and property valuation during the refinancing process. B-20 outlines five core principles for underwriting: 1. **Governance:** Establishes FRFI governance and the development of overarching business objectives, strategy, and oversight mechanisms. 2. **The borrower's identity:** Emphasizes FRFI assessment of the borrower's identity, background, and demonstrated willingness to service their debt obligations on a timely basis. 3. **Borrower's Capacity:** Stresses FRFI assessment of the borrower's capacity to service their debt obligations on a timely basis 4. **Collateral:** Focuses on FRFI assessment of the underlying property value/collateral and management process. 5. **Effective credit and counterparty risk management practices:** Requires FRFIs to have effective credit and counterparty risk management practices and procedures that support residential mortgage underwriting and loan asset portfolio management, including mortgage insurance where appropriate.

Q: What is a 'straight switch,' and how does it impact refinancing at renewal?

A "straight switch" refers to the process of transferring an existing uninsured mortgage to a new institution when it's up for renewal, without increasing the remaining amortization period or the loan amount. OSFI provides certain flexibilities for straight switches.

At a Glance (TLDR)

Expert Research FAQ

Strategic research and verified institutional analysis synthesized for Strategy & FAQ.

How do GDS and TDS ratios affect my refinancing options?

Key Points

What is the Loan-to-Value (LTV) ratio, and how does it impact my ability to refinance?

Key Points

How does OSFI's Guideline B-20 affect refinancing?

Key Points

What is a 'straight switch,' and how does it impact refinancing at renewal?

Key Points

Technical Research Verification

Our systems synchronized 3 data points and regulatory frameworks to verify this technical brief.

Frequently Asked

How do GDS and TDS ratios affect my refinancing options?

What is the Loan-to-Value (LTV) ratio, and how does it impact my ability to refinance?

How does OSFI's Guideline B-20 affect refinancing?

What is a 'straight switch,' and how does it impact refinancing at renewal?

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Refinance•By Ratellow Research Team•Verified 2026-02-18

2026 Canadian Mortgage Refinance Guide: Break-Even Calculator, OSFI B-20 Rules & CMHC Limits

At a Glance (TLDR)

Expert Research FAQ

Strategic research and verified institutional analysis synthesized for Strategy & FAQ.

How do GDS and TDS ratios affect my refinancing options?

Key Points

What is the Loan-to-Value (LTV) ratio, and how does it impact my ability to refinance?

Key Points

How does OSFI's Guideline B-20 affect refinancing?

Key Points

What is a 'straight switch,' and how does it impact refinancing at renewal?

Key Points

Technical Research Verification

Our systems synchronized 3 data points and regulatory frameworks to verify this technical brief.

Frequently Asked

How do GDS and TDS ratios affect my refinancing options?

What is the Loan-to-Value (LTV) ratio, and how does it impact my ability to refinance?

How does OSFI's Guideline B-20 affect refinancing?

What is a 'straight switch,' and how does it impact refinancing at renewal?

Recommended Research

Refinance

HELOC vs. Second Mortgage Canada: 2026 Complete Comparison Guide

Refinance

2026 Canadian Mortgage Refinancing for Renovations: LTV Limits, Stress Test Rules & CMHC Options

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