Following are the general criteria of mandatory registration: • If the total business turnover exceeds INR 40 Lakh/20 Lakh in case of business of goods/providing service respectively in the concerned financial year (Threshold for North-eastern States is INR 20 Lakh/ 10 Lakh in case of business of goods/providing service respectively) • Casual taxable person / Non-Resident taxable person • Agents of a supplier &amp; Input Service Distributor (ISD) • Electronic Commerce Aggregator • Person supplying through an E-commerce platform In addition to above, there are certain other criteria when registration is mandatory. Apart from compulsory registration, one can also apply for GST registration voluntarily.