Registration liability for suppliers triggers mandatory GST registration based on aggregate turnover, transfers and amalgamations. Every supplier making taxable supplies in the State must register under the Act when their aggregate turnover in a financial year exceeds the prescribed thresholds, with a lower threshold for supplies from special category States. Existing registrants under prior law must register from the appointed day. Transfers of a registered taxable business, including succession, require the transferee or successor to register from the date of transfer; transfers under sanctioned amalgamation or de merger require registration from the date the Registrar of Companies issues the incorporation certificate. Aggregate turnover includes supplies on own account or on behalf of principals; job worker supplies after job work are treated as principal's supplies and excluded from the job worker's turnover.