Rectification of advance ruling allows amendment for apparent errors within a fixed period, subject to hearing if tax liability increases. The Authority or the Appellate Authority may amend any advance ruling order to rectify errors apparent on the face of the record within six months of the order if noticed by them or brought to their notice by the concerned officer, jurisdictional officer, applicant, or appellant; however, no rectification that increases tax liability or reduces admissible input tax credit shall be made unless the applicant or appellant is given an opportunity of being heard.