​​​A Permanent Account Number has been made compulsory for every transaction with the Income-tax Department. It is also mandatory for numerous other financial transactions such as opening of bank accounts, in bank account, deposit of cash in bank account, opening of Demat account, transaction of immovable properties, dealing in securities, etc.

A PAN card is a valuable means of photo identification accepted by all Government and non-Government institutions in the country.

Source: Income Tax India’s Official Website