Are you talking about billing the US Postal Service for repairs performed on their vehicles ? They probably are requesting that you accept credit card. A few years ago, the government started using GSA cards(I think that is what it called), and expecting all vendors to accept this type of payment. If you dont accept credit cards, it makes it very difficult to get your foot in the door with any government agency. If you do accept them, it should be fairly easy to get established. If you dont accept plasitc at this time, but are certain that the postal service account will represent a substantial amount of income for you, then by all means do look into being able to takce credit cards. Depending oon your location, though, and if there is no other repair vendor available to them, you might still be able to negotiate with them to pay you the old fashioned way (but usually you have to wait for payment, which could be several weeks, whereas credit card payments are usually credited to your bank account in about 3 days).