A system and method for securing a recurrent billing transaction using a marked proxy code is disclosed. The marked proxy code includes a merchant system marker which is assigned to the merchant and a proxy code assigned to a consumer. An account issuer assigns the proxy code to the consumer and assigns the merchant system marker to one or more merchants. During system operation, a merchant provides an account issuer with a request to establish a recurrent billing account and the account issuer returns to the merchant a marked proxy code including a merchant system marker and the proxy code provided by the merchant. If a merchant requests satisfaction of a transaction, the merchant transaction request includes the marked proxy account number. The account issuer receives the marked account number and validates the merchant system marker and the proxy code prior to validating the merchant's transaction request.