Cancellation of GST registration: applications must be accepted unless incomplete or transfer unregistered, with specified final return obligations. Applications for cancellation under FORM GST REG-16 must include contact, reason and effective date, stock and tax particulars, transfer particulars where applicable, and last return details. Proper officers should accept and issue FORM GST REG-19 within thirty days except when applications are incomplete or transferee entities lack registration; in such cases officers must notify discrepancies, allow seven working days to respond, and may approve or reject after hearing. The effective cancellation date is the date sought and cannot precede the application date.