A system and method for securing a financial transaction using a proxy code, which is assigned a transaction account number. An account issuer permanently assigns the proxy code to a transaction account correlated to the transaction device. The proxy code is uploaded onto the transaction device for later use in completing a transaction request. During transaction completion, the proxy code is provided to a merchant system in lieu of any sensitive account information. Since the proxy code is permanently assigned, the number need not be changed or updated on the merchant system once uploaded into a payment device or merchant database. The account issuer may manipulate the sensitive account information without need to alter the information stored on the merchant database. Since the proxy code contains no sensitive information, the sensitive information related to the transaction account is secured from theft.