Whatever the contract says. But if you have a long term deal, I would recommend quarterly, or preferably annual billing. Dealing with checks is a pain. In my ex

Whatever the contract says. But if you have a long term deal, I would recommend quarterly, or preferably annual billing. Dealing with checks is a pain. In my experience, big co's are no more or less likely to pay on time than anyone else. But they don't tend to pay early. If it's small recurring billing, just have them use a credit card. Even then, annual billing is preferred - it cuts down on the requests for invoices from their accounting departments in addition to the obvious cash flow advantages of collecting a year up front.