Abstract: A payment website coordinates payment transactions related to purchases by account holders from merchants. Merchants may open transactions and request authorization from the account holders' account issuers. Upon receipt of a favorable authorization response in a particular transaction, the website may permit the merchant to append an invoice to the transaction on the website for validation by the account issuer. The account issuer may confirm that the invoice meets requirements for an applicable financing program. After validation of the invoice, the payment website may contact the account holder to obtain authentication by the account holder of the invoice and the transaction.