Registration under GST requires timely application, distinct registrations for establishments, and PAN or Aadhaar-based identity verification. Every person liable to GST registration must apply in each State or Union territory where liable within prescribed time, with casual and non-resident persons subject to special timelines and SEZ units requiring separate registration. Applicants must hold a Permanent Account Number or prescribed alternative and registered persons must undergo Aadhaar authentication or furnish alternate identification as specified. Multiple registrations are treated as distinct persons; proper officers may register defaulters; certain international agencies and notified persons may receive a Unique Identity Number; registrations are granted, rejected or deemed granted after prescribed verification and periods.