Merchants may require minimum purchase amounts on credit card transactions. Documents requiring notarized signature will NOT be accepted if the signature is more than three-months old at time of submittal.Interchange is generated when your customers make purchases with debit and credit cards. Find out how it works and discover how much you could be earning. Some guidelines include: • Purchasing cards may be used to pay for all business expenses including travel, meals, entertainment, supplies and vendor invoices. If you require a unique timeframe, you will need to complete the registration form and contact the parking office manager for rates and payment arrangements. Applicants can order a GIS. Identify the parties involved in the transaction. 2. When a purchase is made using a P-Card, ask the vendor to exclude the sales tax from the cost of the transaction.