What is a Payoff Agreement? A payoff agreement is an informal contract in which a creditor agrees to accept the balance of a debt owed as full payment.A mortgage payoff letter can come in two forms. One form tells borrowers the remaining principal amount and interest they have to pay to close out the loan. Do you have questions? Creating a payoff letter is essential to any loan or mortgage repayment process. Our free templates and this guide can help you get started. Send sample payoff letter for private mortgage via email, link, or fax. You can also download it, export it or print it out. Creating a payoff letter is essential to any loan or mortgage repayment process.