A 10day payoff refers to the time it takes for your new lender to pay off your old loans during a refinance. I have a car loan from ally that I am trying to refinance, the new lender has asked for a ten day pay off balance quote, I'm unsure what I'm supposed to send.Per diem interest determines your mortgage's interest payments between closing day and the day you start making standard monthly payments. Your 10day payoff letter is crucial to ensuring that your new lender sends the correct amount of money so there is no outstanding loan balance left over. By including a per diem amount in the letter, the parties will not have to execute another payoff letter if the termination date. What is a Payoff Agreement? A payoff agreement is an informal contract in which a creditor agrees to accept the balance of a debt owed as full payment. A 10-day payoff statement is a document from your lender that gives us the payoff amount to purchase your vehicle, including 10 days worth of interest. That will give you the per diem interest (daily interest). Discover more about per diem interest—the daily interest on a loan that occurs outside of the standard repayment period.