Authorised representative rules permit specified agents to appear in GST proceedings, with statutory disqualifications applying. The Bihar GST Act allows appearance by an authorised representative except where personal examination on oath is required. 'Authorised representative' includes relatives or regular employees; advocates not debarred from practice; chartered accountants, cost accountants or company secretaries holding a certificate of practice and not debarred; certain retired commercial tax officers subject to a one-year post-retirement bar; and authorised GST practitioners. Disqualifications include persons dismissed from government service, convicted of GST-related offences, found guilty of misconduct, or adjudged insolvent, with disqualifications under central or other GST laws deemed effective under this Act.