How does CRA tell the difference between maintaining a rental property and improving it?

CRA uses a handful of practical factors rather than one bright-line rule. It asks whether the expense provides a lasting benefit to the property, whether it's a repair to part of the property or a replacement or improvement of the whole thing, whether the work is in keeping with the property's original condition when you acquired it, and whether it's a single, isolated repair or part of a larger renovation project. Maintaining generally means restoring or preserving what was already there; improving means making the property better, more valuable, or different than it was.

None of these factors is decisive on its own, which is why this area causes so much confusion - the same type of work can land differently depending on scope and context. Replacing something with a modern equivalent that just restores function, without materially upgrading it, usually still counts as maintenance. A full-scale renovation, or several repairs bundled together into one larger project, tends to tip toward improvement even if each piece looks small in isolation. Because the line is genuinely a judgment call in many real situations, keeping detailed records of what was done, why, and whether it was standalone or part of something bigger is the best protection if CRA ever questions the treatment.