The three buckets
- Legal & registered — Development Permit obtained, Building Permit closed with final inspection, and the property is listed on the City of Calgary Secondary Suite Registry.
- Legal non-conforming — the suite pre-dates the current land use rules and is grandfathered, but does not meet all current code items. Rules vary; the City treats these case-by-case.
- Illegal — the suite exists but has no permit history, and the property is not on the Registry. This is what you most often see in MLS® remarks worded as "illegal suite," "non- conforming," or "suite not registered."
Insurance
Most Canadian insurers will refuse to write a homeowner policy on a property with a known illegal suite, or will exclude the suite from coverage entirely. That means a basement fire that starts in the illegal kitchen may not be covered — and your mortgage lender requires insurance.
Financing & appraisal
Big-Five lenders will typically only count 50–100% of rental income from a legal suite toward mortgage qualification. Income from an illegal suite is usually excluded, which can drop your maximum purchase price by tens of thousands of dollars.
Resale value
Comparable legal-suite homes in the same Calgary community regularly sell for a noticeable premium over identical illegal-suite homes — often in the $30,000–$60,000 range for a typical inner-city bungalow. The premium exists because the pool of qualified buyers is much larger.
Tenant safety & liability
Illegal suites often lack the specific egress, fire separation and alarm requirements that make basement units survivable in a fire. A landlord who rents out an illegal suite is exposed to significant civil liability if a tenant is injured.