GST registration requirement: liability-based application, single registration norm, and separate registrations for business verticals. Registration requires liable persons to apply within the prescribed period, with casual and non-resident taxable persons applying earlier; supplies from territorial waters are registered in the State of the nearest baseline. A single registration is standard, with separate registrations for business verticals allowed. Voluntary registration is permitted. Each registration or establishment in different States is treated as a distinct person. PAN is required for eligibility, with TAN accepted for certain deductors and prescribed alternatives for non-resident taxable persons. Proper officers may register non-compliant persons, special entities may receive a Unique Identity Number, and registration or UIN are granted, rejected or deemed granted after prescribed verification and timelines.