Canada's banking regulator is testing a new mortgage rule that could take effect by spring 2026, capping mortgages at 4.5 times your gross household income. This replaces the current "stress test" system where you prove affordability at higher rates. Under the new system, someone earning $150,000 would max out at a $675,000 mortgage, regardless of interest rates or other factors. High earners in affordable cities may qualify for more, while lower income borrowers and those in Vancouver/Toronto face tighter limits. Currently, only 12% of mortgages exceed this threshold, so most people won't be affected at today's rates. However, if rates drop significantly, this cap will become the main constraint. The regulator will make a final decision between April and June 2026, with possible outcomes including replacing the current system, keeping both, or modifying existing rules.