An invoice is the document issued by the supplier to the Postal Service that provides a detailed list of goods delivered or services rendered and accounts for all amounts to be paid. Once received, invoices are processed by the designated individual specified in the contract or order. Invoices must be submitted in accordance with Clause 4-1: General Terms and Conditions, Invoices (paragraph g) or Clause B-20: Invoices. Depending on the particular purchase, these terms and conditions may be modified.