Registration requirement: liable persons must apply timely and satisfy PAN eligibility for GST registration; special treatment for non-residents. Registration requires liable persons to apply within prescribed timeframes, with single registration as default and separate registrations for distinct business verticals; voluntary registration is permitted. Eligibility requires a Permanent Account Number or prescribed alternates for non-residents and certain deductors may use a Tax Deduction and Collection Account Number. Proper officers may register non-compliant persons; certain notified international or other entities may receive a Unique Identity Number. Granting or rejection follows prescribed verification and is deemed granted if no deficiency is communicated within the prescribed period.