Prepayments for Purchase Orders Sometimes you have to provide a prepayment when you remit a purchase order for inventory items, at least until you've developed a financial history with your supplier. Some suppliers insist on a percentage of the total cost, while other suppliers may ask for the entire amount of the purchase. We've created instructions for managing prepayments. This is a PDF file, so you must have Acrobat Reader to open it (if you don't have the software, you can download it from www.adobe.com - it's free. Click here to open the PDF file.