A Third Overdue Payment Reminder is a type of reminder sent to a customer when payment for a purchase or service has not been received after a certain period of time. This type of reminder is usually sent after two other reminders have already been sent. It is the final reminder before any further action is taken. There are two types of Third Overdue Payment Reminders: a polite reminder and a more assertive reminder. A polite reminder is usually sent as a courtesy to the customer and includes a polite request that the payment be made soon. A more assertive reminder may include a warning that the customer’s account will be sent to collections if payment is not received within a certain period of time.