Registration threshold: suppliers must register when aggregate turnover exceeds the applicable limit and on business transfers. Section 22 requires registration where a supplier's aggregate turnover in a financial year exceeds the applicable threshold for the State or Union territory of supply, with distinct treatment for special category States and for persons engaged exclusively in supply of goods; the Government may enhance thresholds by notification. Registration is also mandatory for persons registered under prior law on the appointed day, for transferees or successors on transfer of a business as a going concern, and for persons acquiring businesses pursuant to court sanctioned amalgamation or demerger. Government departments supplying used or seized goods to unregistered persons must register and pay GST, subject to Sections 22 and 24.