Central Goods and Services Tax amendment allows existing authorities to hear appeals until National Appellate Authority is constituted. The amendment permits the Government, on the Council's recommendation and by notification, to empower any existing authority to hear appeals under section 101B until the National Appellate Authority is constituted; in that event sub sections (2) to (13) of section 101A shall not apply and references to the National Appellate Authority in the Chapter shall be construed as references to such empowered authority, with 'existing Authority' expressly including a Tribunal.