By including a per diem amount in the letter, the parties will not have to execute another payoff letter if the termination date. A 10 day payoff is crucial to getting your old loans paid off during a refinance.Learn how it works from start to finish. Please accept this as my authorization to issue a payoff statement to. Through an effective date of . Please provide payoff information for the above referenced mortgage. Also, please provide loan number and per diem interest. A payoff agreement is an informal contract in which a creditor agrees to accept the balance of a debt owed as full payment.