Rectification of advance ruling allows amendment for errors apparent, subject to hearing before measures raising tax or reducing input credit. Authority or Appellate Authority may amend an advance ruling to rectify any error apparent on the face of the record, on its own motion or when notified by officers or the applicant/appellant, within a limited period from the date of the order; however, no amendment that increases tax liability or reduces admissible input tax credit shall be made without giving the applicant or appellant an opportunity of being heard.