The mortgage payoff calculator helps you find out. Early Payoff Calculator.They'll figure out the amount at closing and you'll get the right amount. 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. Mail your loan payment to: P.O. Box 953. Loans are billed monthly following the expiration of your initial grace period and all payments are due on the first of each month. Learn more about Wayne State University's tuition and fees. If you're worried about how to get out of debt, here are some things to know — and how to find legitimate help.