By including a per diem amount in the letter, the parties will not have to execute another payoff letter if the termination date. A 10day payoff refers to the time it takes for your new lender to pay off your old loans during a refinance.Reduce title release and vehicle payoff from weeks to days through ACH payoff and expedited payment to lenders. Cut costs, save time, move inventory faster. Calculate your per diem allowance for your trip. Simply enter your travel dates and details to find out your per diem allowance. Nevada per diem calculator. To calculate your per diem allowance, enter the dates of your business travel along with the location, county, and city. ‍. 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.