BMO Harris Bank Auto Loan Payoff Address: Standard Mailing PO Box 6201 Carol Stream IL 60197. Contact BMO Harris Bank for complete details.It's the payoff amount 10 days in the future. Create a Loan Payoff Letter online and download it as a PDF or Word document. Customize and print a blank Loan Payoff Letter for free. Hitting a loan payoff goal is one of the best financial feelings in the world. Your bank, however, has a completely different take on it. Get access to direct deposit forms, automatic bill payment forms, and loan management from BMO. An auto loan payoff letter is just a way to prove that you have paid in full for a car. If you are selling your vehicle, often the buyer will ask to.