Aadhaar linking requirement: eligible persons must quote or intimate Aadhaar or Enrolment ID, non-compliance affects PAN operability. Every person eligible for Aadhaar must quote their Aadhaar number (or Enrolment ID if Aadhaar is not yet possessed) in PAN applications and income-tax returns; persons already holding PAN must intimate their Aadhaar to the prescribed authority by a notified date, failing which the PAN shall be made inoperative. The Central Government may notify exemptions by person, class or territory, and statutory definitions adopt the Aadhaar Act meanings while delegating procedures, forms and timing to prescribed rules and notifications.