Aadhaar linking requirement: PAN applicants and filers must quote Aadhaar or enrolment ID; failure may invalidate PAN. A new section mandates that persons eligible for Aadhaar must quote the Aadhaar number when applying for PAN and in income tax returns from 1 July 2017; an enrolment ID may be used if Aadhaar is not yet assigned. Existing PAN holders eligible for Aadhaar as of that date must intimate their Aadhaar in the prescribed form and manner by a notified date, failing which the PAN shall be deemed invalid. The Central Government may notify exemptions and the section adopts Aadhaar Act definitions, including the 28 digit enrolment ID.