A vehicle payment plan agreement is a contract between a buyer and seller of a vehicle that agrees to installment payments. A car sale payment agreement is used when the purchase price of the car is paid in instalments.1. Insert the Vehicle Service Contract number in the upper, right-hand corner. 2. Complete the Purchaser and Dealer information. If an Ohio resident assumes an out of state lease, Ohio use tax may be due and payable up front on the remainder of the lease payments. CocoDoc collected lots of free vehicle purchase agreement with monthly payments for our users. Only way would be to write up a contract saying payments are non refundable and the vehicle will be handed over once final payment is made. Sufficient income, credit and a history of paying debts on time are among the top criteria lenders seek in an applicant.