When the Aadhaar mandate rolled out in 2009, it was not very popular with the masses except for those who needed a quick LPG connection. 10 years later, more than 120 crore Indians now have an Aadhaar number and for the ease and convenience of taxpayers, the government has proposed to make the age-old PAN and Aadhaar interchangeable. This would allow those who do not have a PAN number to file income tax returns via Aadhaar. They may also use it wherever else the PAN number is required to be quoted.
Income Tax Budget 2019 - Consequences of failing to link Aadhaar and PAN
At present, if the PAN is not linked with Aadhaar, provisions state that the PAN will be made invalid. In order to protect past transactions carried out through the usage of such a PAN, the government proposes that if the user fails to intimate the Aadhaar number, the PAN allotted will be made inoperative.