Creating a payoff letter is essential to any loan or mortgage repayment process. Our free templates and this guide can help you get started.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. The loan payoff statement includes your principal balance, any outstanding interest due, and potentially any prepayment penalty (if applicable). A Paid in Full letter will be sent to you approximately 30-45 days after the payoff payment is applied to your loan. A 10 day payoff is crucial to getting your old loans paid off during a refinance. Learn how it works from start to finish. In the formula, B stands for the payoff balance due in dollars. L is the total loan amount in dollars.