Registration liability arises where a supplier's aggregate turnover exceeds prescribed thresholds, with special state and transfer rules applicable. Registration liability arises where a supplier's aggregate turnover in a financial year exceeds prescribed thresholds, with lower thresholds and possible statutory enhancements applicable to special category States and separate treatment for suppliers exclusively of goods. Transitional rules require prior registrants to register from the appointed day; transfers of businesses as going concerns, successions, and corporate amalgamations/demergers trigger registration, with amalgamation registration tied to the Registrar of Companies' incorporation certificate. Explanations define aggregate turnover, allocate post job work supplies to principals, and identify special category States.