I agree completely with Rod. If the customer is not a big part of your overall receivable, then the only other possible consideration is do they have the potential to become a big part? Will they overcome their current cash flow difficulties? If your gut instincts tell you the answer to both of those questions is no, then prepayment is the way to go. Even if they don't have cash flow issues but their accounts payables department is managed poorly, that's still an issue you may want to stay away from.