Acknowledgment of E-Filing of the return **************************************** : In the case of a Central Excise or service Tax return filed on-line, ACES application software acknowledges it by displaying an Acknowledgement message. A unique document reference number is generated which consist of 15-digit registration number of the assessee, name of the return filed, the period for which return is filed etc. This is also automatically communicated to the email id of the assessee by the application. In the case of an uploaded Central Excise return, using offline utility, similar acknowledgement is generated and sent after the acceptance of the return by the system as a valid return i.e. when the status changes to ‘FILED’