Registration liability for suppliers triggers mandatory registration when turnover exceeds prescribed threshold, with special rules for existing registrants and transfers. Suppliers of taxable goods or services must register when their aggregate turnover in a financial year exceeds the prescribed threshold, with a lower threshold for supplies from special category States. Aggregate turnover includes all supplies by the taxable person on own account or on behalf of principals; supplies by a registered job worker after job-work are treated as supplies of the principal and excluded from the job worker's turnover. Existing registrants under prior law must be registered from the appointed day. Transferees or successors of registered businesses carried on as going concerns are liable to register from the date of transfer, and transfers by sanctioned amalgamation or de-merger trigger registration from issuance of the certificate of incorporation.