Composition levy opt-out registrants below threshold must pay state tax at time of supply and file returns promptly. Registered persons whose aggregate turnover in the preceding year did not exceed the statutory threshold, or whose turnover in the year of registration is likely to be below that threshold and who did not opt for the composition levy, are notified as a class required to pay state tax on outward supplies at the time of supply (including cases attracting supply-adjustment rules), and to furnish prescribed returns and details and remit tax within the periods specified by the Act.