CostThe home you're buying has a basement apartment or laneway suite that's either already rented or could be — and whether it actually helps your mortgage application depends entirely on whether it's a legal, permitted suite.
What usually happens
Lenders will generally only count secondary suite rental income toward your qualifying income (see our rental income and mortgage approval guide for how that offset typically works) if the suite is a legal, permitted unit under the local municipality's zoning and building code — not simply a finished basement someone happens to be renting informally. An illegal or unpermitted suite, even if currently generating real rent, often can't be counted at all in your qualifying calculation.
What to verify before you count on it
- Zoning compliance — confirm the municipality actually permits a secondary suite on this specific property, since not every zone allows one.
- Building permits — a legal suite should have permits on file for its construction or conversion; ask the seller or municipality directly rather than assuming.
- Separate egress, fire separation, and other code requirements — legal suites typically need to meet specific safety standards beyond simply being livable space.
- Whether the current rental arrangement (if any) is documented — a lease and payment history strengthens your case with a lender, if the suite is otherwise legal.
Who to ask
Ask the listing agent or seller directly for permit documentation, and independently verify with the municipality if the suite's legality materially affects your decision to buy or your financing plan — don't rely solely on a verbal assurance that "it's legal." A mortgage broker can also confirm in advance whether your specific lender will count the income, and under what documentation requirements.
Model your numbers with and without the suite's income counted on the rental cash flow calculator and affordability calculator.