It is now mandatory to link the two personal identification numbers for carrying out income tax-related tasks such as filing of returns.

According to Section 139 AA (2) of the Income Tax Act, every person having a PAN on July 1, 2017 and eligible to obtain Aadhaar must intimate the Aadhaar number to tax authorities.

The government had extended the last date for the mandatory linking of the two identification numbers six times in the past.

The Supreme Court had in September 2018 declared the government's flagship Aadhaar scheme as constitutionally valid and held that quoting of the Unique Identity Number (UID) would remain mandatory for filing of income tax returns and allotment of PAN. Top Court Asks If Centre Plans Aadhaar Verification For Social Media

In the first Budget of Prime Minister Narendra Modi's second term, the government allowed interchangeability of Aadhaar with PAN under income tax rules. (Also read: Aadhaar Compulsory For New Dealers From January 2020, Says GST Network)

Assessees can now file their income tax returns by furnishing Aadhaar instead of PAN.

However, in such cases, the PAN is generated automatically, according to the Central Board of Direct Taxes, the top policymaking body for the Income Tax Department.

Issued by the Income Tax Department, PAN is a 10-character alphanumeric personal identification number that enables the taxman to link financial transactions with individuals. Aadhaar is a 12-digit identification issued by the Unique Identification Authority of India (UIDAI).