A payoff letter shows the remaining balance on your mortgage, including fees, interest, etc. Learn more about what a payoff quote is and how to request one.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. A mortgage lender might ask you to write a letter of explanation to better understand your finances when deciding whether to approve you for a loan. What Is a Letter of Explanation? A letter of explanation is a document that the lender may request to learn more about your specific financial situation. With our mortgage payoff calculator, discover how much you could save on your mortgage. This form is a statement of final loan terms and closing costs. This part explains what you can deduct as home mortgage interest.