Rectification of advance ruling: Authority may amend orders to correct errors apparent on face of record within six months. The Authority or the Appellate Authority may amend an advance ruling order to rectify any error apparent on the face of the record, on its own motion or on notice from specified officers or parties, within a prescribed post order period; provided that any rectification that increases tax liability or reduces admissible input tax credit requires that the applicant or appellant be given an opportunity of being heard.