Is a vendor take-back note secured against the business itself or against my personal assets?

It depends entirely on what the buyer and seller actually negotiate and document, since a vendor take-back note is not automatically secured against anything just by existing. A common approach is for the seller to register a security interest under Ontario's Personal Property Security Act against the purchased business's own personal property, such as equipment, inventory, and receivables, and to take a mortgage or charge against any real property included in the deal, giving the seller a defined claim against the business assets specifically.

A seller can also negotiate additional personal security from the buyer, such as a personal guarantee or a pledge of the shares issued as part of the purchase, which would extend the seller's recourse beyond just the business's own assets. Without any registered security or personal guarantee in place, a note by itself generally leaves the seller as only an unsecured creditor, with a contractual right to be paid but no priority claim against any specific collateral if the buyer runs into financial trouble. Which of these applies in a given deal is a product of negotiation, not a default.