The income gets folded into the same two ratios every application runs through: roughly 39 percent of gross income on housing costs and 44 percent on total debt. Counted rental income lowers both ratios, which is why it can turn a marginal application into an approved one.
None of that counts without paperwork. A signed lease and, where the unit is a second suite, a legal secondary suite permit from the City of Saskatoon are what let a lender count the income at all, so get that documentation in order before you count on the number.
Joel Dyck can point buyers toward a mortgage broker who runs the real numbers on a specific two-family property before an offer goes in. Get your hand-reviewed valuation from Joel Dyck.