Registration liability based on aggregate turnover triggers compulsory GST registration, with special lower threshold for certain states. Suppliers of taxable goods or services must register when their aggregate turnover in a financial year exceeds the relevant threshold, with a lower threshold for supplies from special category States. Supplies made on behalf of principals count toward aggregate turnover, while goods supplied after completion of job work are treated as principal supplies and excluded from the job worker's turnover. Persons registered under prior laws must register from the appointed day. Transfers of a registered business as a going concern require the transferee or successor to register from the transfer date, and transfers under sanctioned amalgamation or demerger schemes require registration from the date the Registrar of Companies issues the incorporation certificate.