CBIC is implementing the system of digital generation of Document Identification Number (DIN) for all communications sent by its offices to taxpayers. This would create a digital directory for maintaining an audit trail of such communication.
As per Circular No. 37/2019-Cus. and Circular No. 122/41/2019-GST, both dated 5-11-2019 issued in this purpose, no authorization, summons, arrest memos, inspection notices and letters in the course of an enquiry shall be issued on or after 8-11-2019 without a computer generated DIN.
Communications may be issued without DIN in exceptional circumstances however that would only be so after recording the reasons in writing. Any specified communication which does not bear DIN and not covered under specified exceptions, shall be invalid.