# How the Mortgage Stress Test Calculator Works

> OSFI Guideline B-20, the Minimum Qualifying Rate, GDS/TDS, and the November 2024 straight-switch exemption.

Category: Calculator Guide
Last verified: 2026-08-02
Source: https://ratellow.com/mortgages/stress-test-calculator/guide

## TL;DR
- The 5.25% floor and contract+2% structure of the MQR are unchanged through 2026.
- Stay with the incumbent is not a newly underwritten mortgage. A qualifying straight switch is prescribed-MQR exempt. A refinance is always inside the test.
- Provincially regulated credit unions and most private lenders are outside OSFI B-20 and may use their own qualifying rules.