Private Loan Payoff Letter Template offers a clear and professional format for requesting an official statement of your loan payoff balance. Make a payment on your Wintrust Mortgage online, learn how to request your payoff quote, and send your mortgage payoff.An IOU (I Owe You) is a legal document that sets out the details of a loan made between two people, a borrower, and a lender. If interest is charged, the rate should be included with a repayment schedule. It should detail the amount due, itemizing any penalties or interest, along with any acceptable payment plans. Payoff Letter: A document used to pay off an existing loan or mortgage. Payoff statements alert borrowers to how much they must pay to fully satisfy a loan. The document helps ensure the deal is legal. It typically details the principal balance, interest due as of that date, per diem, any late fees, etc. Payoff of first mortgage loan. 103.