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 payoff letter provides instructions on how to pay off a loan with a lump sum before the loan term ends. Learn how payoff letters work. 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. The key part - "You tell them what day you want to pay it off. " They absolutely need this information to give you the correct payoff amount. 1) Call the mortgage department and request an official principal payoff letter. First you need to know what the payoff figure is.