Conflicting advance rulings trigger appeal to the National Appellate Authority within prescribed limitation and filing requirements. Appeal to the National Appellate Authority lies where conflicting Advance Rulings are issued by Appellate Authorities of two or more States or Union territories on questions covered by section 97(2). An appeal may be filed by an authorised officer or by an aggrieved distinct applicant, subject to the specified State-based condition. The appeal period is thirty days, or ninety days for an authorised officer, with a further thirty-day extension for sufficient cause. Limitation runs from communication of the last conflicting ruling, and the appeal must be in the prescribed form, fee and verification.