Can a corporation grant a security interest over its bank accounts to a lender?

Yes. A corporation's bank accounts are a form of intangible personal property under Ontario's Personal Property Security Act, and a lender can take a security interest in them, generally as part of a broader general security agreement covering the corporation's present and after-acquired property, though a lender can also take security specifically targeted at particular accounts.

Registering a financing statement under the PPSA is the standard way to perfect this kind of security interest, but registration alone doesn't give the lender direct control over the account or the bank's cooperation in a default. For that reason, lenders who want stronger, more immediate protection over specific bank accounts often also seek a control agreement involving the bank itself, giving the lender the ability to act on the account directly if the corporation defaults, rather than relying solely on the registered interest and having to pursue collection through other means. If your corporation is negotiating financing that includes security over its operating accounts, expect the lender to ask about both registration and, potentially, a separate arrangement directly with your bank.