The Budget 2019 proposed to make PAN and Aadhaar interchangeable. According to the announcement, if you do not have PAN, you can file your IT returns using Aadhaar. Also, you can quote your Aadhaar number wherever PAN is mandatory.
The government took this initiative to improve tax compliance and make life simpler. The speech further proposed mandatory quoting of PAN/Aadhaar in order to track high-value transactions.
Based on the current income tax laws, it is necessary to quote PAN while filing ITR. With effect from 1 April 2019, it is compulsory to quote Aadhaar and link it with PAN while filing ITR.