Rectification of advance ruling allows amendment for apparent errors, with hearing if tax liability increases or input credit is reduced. Rectification permits the Authority or Appellate Authority to amend an advance ruling to correct an error apparent on the face of the record, on its own motion or when notified by concerned officers, the applicant or appellant, within six months of the order; provided that any rectification that would enhance tax liability or reduce admissible input tax credit requires giving the applicant or appellant an opportunity of being heard.