4C. Authentication by digital signature - (1) Any invoice, bill or challan issued under rule 4A or consignment note issued under rule 4B may be authenticated by means of a digital signature.

Provided that a person located in non-taxable territory providing online information and database access or retrieval services to a non-assesse online recipient located in taxable territory may issue online invoices not authenticated by means of a digital signature for a period upto 31st January, 2017’

Inserted vide Notification 53/2016-Service Tax

(2) The Board may, by notification, specify the conditions, safeguards and procedure to be followed by any person issuing digitally signed invoices.]