Can a buyer assume the seller's existing mortgage when purchasing a commercial property in Ontario?

Only with the lender's consent. Assuming a seller's existing commercial mortgage isn't automatic just because the buyer would like to keep the existing financing in place. Most commercial mortgages include a due-on-sale or no-assumption clause requiring the lender's prior approval before a new owner can step into the borrower's position, and lenders typically use that leverage to re-underwrite the buyer, potentially updating the interest rate, term, or other conditions rather than simply carrying the loan forward unchanged.

The nuance buyers often miss is timing: getting lender consent takes coordination and can affect the closing date, so this needs to be raised early in negotiations rather than assumed as a formality near the end. If the lender says no, or only agrees on materially different terms, the buyer needs a backup financing plan in place so the deal doesn't stall. Assumption also doesn't automatically release the seller from liability unless the lender specifically agrees to that as part of the assumption.

Before relying on an assumption as part of the purchase price or financing structure, a buyer should confirm in writing, early in the process, whether the lender will actually permit it and on what terms.