Aadhaar-PAN linking requirement may render PAN inoperative if eligible persons fail to intimate Aadhaar to tax authorities. Every person eligible for Aadhaar must quote Aadhaar when applying for PAN or filing returns, and may quote an Aadhaar enrolment ID if Aadhaar is not yet allotted. Persons who held PAN by the relevant operative date were required to intimate their Aadhaar by the statutory deadline, failing which PAN shall be made inoperative; a later notification deferred the date on which the inoperative-PAN consequences would take effect.