Compulsory GST registration required for specified categories including inter State, casual, non resident suppliers and electronic commerce operators. Compulsory registration is required for specified classes regardless of general thresholds: inter State suppliers; casual and non resident taxable persons; persons liable under reverse charge and under sub section (5) of section 9; persons required to deduct tax; agents or persons supplying on behalf of others; Input Service Distributors; electronic commerce operators and suppliers of online information and database access from outside India to unregistered persons; supplies through e commerce operators collecting tax at source; and any other classes notified by the Government on Council recommendation.