The Document Identification Number (DIN) is a unique number required for all taxpayers to communicate with India's Income Tax department. Section 282B of the Finance Act of 2010 established DIN and mandates its use on all incoming and outgoing tax communications to verify authenticity and prevent denial of communications. DIN can be used for notices, orders, letters, refund claims, and accurate tax filings and will be issued by the Income Tax department and Aayakar Sampark Kendras to help bring more transparency to tax administration.