Compulsory GST registration required for inter state, reverse charge, e commerce, casual, tax deductor and Input Service Distributor suppliers. Compulsory registration is required for specified categories under the Kerala GST ordinance, including persons making inter state taxable supplies, casual taxable persons, persons liable to pay tax under reverse charge, non resident taxable persons, persons required to deduct tax, Input Service Distributors, agents making supplies on behalf of others, electronic commerce operators and suppliers through such operators, and persons supplying online information and database access services from outside India to unregistered recipients; additional classes may be notified by the Government.