Your Permanent Account Number (PAN card) will turn useless from April 1, if you don't link it to your Aadhaar card. Linking PAN with Aadhaar had been extended several times by the central government.
The last date to link the documents is March 31, 2021, unless the government extends the deadline again. After the deadline ends, all the PAN cards which are not linked to Aadhaar would be useless and declared "inoperative". You will not be able to do any financial transaction if your PAN is not linked to your Aadhaar.
A penalty of Rs 10,000 may apply as per Section 272B of the Income Tax Act if you fail to link the two documents by the deadline and your PAN becomes inoperative and it will be assumed that your PAN has not been furnished as required by the law.
Opening a bank account, buying mutual funds or shares, and even making cash transactions of over Rs 50,000 are the several purposes for which a PAN card is mandatory.