The debt service coverage ratio is the commercial equivalent of the residential GDS/TDS ratios covered in Course 05, and it plays a similar role: it is the primary test of whether the income supporting a loan is enough to comfortably cover the payments on it. The formula is simple — DSCR = Net Operating Income ÷ Annual Debt Service — where net operating income (NOI) is covered in detail in module 03, and annual debt service is the property's total scheduled principal and interest payments for the year.
A DSCR of 1.0 means the property's income exactly covers its debt payments, with nothing left over. A DSCR of 1.25 means the property generates 25% more income than its debt payments require — a cushion that absorbs a vacancy, a rent-collection problem, or a maintenance surprise without the property falling behind on the mortgage. Lenders want that cushion, and the size of the cushion they require is the number this whole module is about.
As flagged in module 01, commercial underwriting is not standardized the way residential underwriting is, and DSCR minimums reflect that directly. Broadly, major bank lenders tend to sit at the higher end of the typical range, often around 1.25 to 1.30, reflecting their generally more conservative underwriting posture. Credit unions and some alternative commercial lenders often work in a somewhat lower range, commonly cited around 1.20 to 1.25. CMHC's multi-unit insurance programs — covered in module 09 — can accept DSCR as low as 1.10 at their most favourable tiers, reflecting the credit enhancement the insurance itself provides to the lender.
The honest lesson here is not to memorize a single minimum and repeat it to every client. Property type, tenant quality (module 06), and whether the loan is insured all shift where a given lender will actually land, and quoting one number as universal is exactly the kind of overconfident claim that undermines a broker's credibility with a sophisticated commercial client.
A property's actual DSCR, calculated on today's income and today's mortgage payment, is only the starting point. Many commercial lenders also calculate a stressed DSCR, applying a higher assumed interest rate — sometimes the contract rate plus one or two percentage points, sometimes a fixed floor rate — to see whether the property would still clear the minimum coverage if rates moved against the borrower at renewal. This mirrors, conceptually, the minimum qualifying rate concept in residential lending covered in Course 01, though the mechanics and the specific stress applied are set by each lender rather than by a single national standard.
A property that clears 1.25 DSCR at today's rate but would fall below 1.10 under a stressed rate is a meaningfully different file than one that clears 1.25 under both scenarios, even though the headline number looks identical. Understanding which test a given lender is actually applying — and asking, rather than assuming — is part of correctly reading a commercial approval.
A property that does not meet a lender's DSCR minimum on its current numbers is not automatically declined — it usually means the loan amount needs to come down (reducing annual debt service to restore the ratio), the borrower needs to inject more equity, additional security or a personal guarantee needs to be added (module 08), or the file needs to move to a lender whose typical range better fits the property. This is a normal, common negotiation on commercial files, not a rare edge case, and is one of the more frequent reasons a broker shops a commercial deal across several lender types before landing on the right fit.
A property generates $180,000 in annual net operating income against $150,000 in annual debt service. What is its DSCR, and what does that figure indicate?
DSCR = NOI ÷ Annual Debt Service = $180,000 ÷ $150,000 = 1.20, meaning the property produces 20% more income than its debt requires — a real, positive cushion, comfortably inside the typical range most lenders look for. The tempting wrong answer inverts the formula (debt service divided by NOI), which would understate coverage rather than measure it; DSCR is always expressed as a ratio with income on top, precisely because the question being asked is how much cushion the income provides above the debt, not the reverse.
