A Second Request for Payment is a document that is sent after an invoice has been issued to a customer but has not been paid. It is a reminder to the customer that payment is still outstanding and is an important step in collecting overdue payments. There are two main types of Second Request for Payment, depending on the payment terms of the original invoice. The first is an Overdue Notice, which is sent if the payment terms stated on the invoice have been exceeded. The second type is a Past Due Reminder, which is sent if the payment terms of the invoice have not been met. Both types of Second Request for Payment will usually include a polite reminder of the outstanding balance, the original invoice number, and the payment terms of the invoice. They may also contain a warning of potential legal action if payment is not received.