An open invoice, often known as an outstanding invoice in British terms, is a document the seller provides to the purchaser for goods or services received but not yet paid for. It signifies that the payment remains due. Grasping the concept of an open invoice lays the groundwork for effective cash flow management alongside a solid understanding of legal requirements in the United Kingdom. The approach taken to manage open invoices can greatly differ based on a business's internal practices and the specified details of each business transaction.