This Payment Past-Due Reminder Letter Template sets forth an initial, friendly reminder to a party that a payment is past due and owing on an invoice. The letter could be sent by any individual or business who has previously sent an invoice to a person or business, and such invoice has not yet been paid. This document contains the essential information that should be included in such a reminder letter, including the account number, the original due date, the amount due, and payment instructions. It may be customized to fit the specific needs of the user. This should be used by companies when its customers' payments are past due.