GST procedural timelines and forms updated; input tax credit declaration, payment methods, UIN application and AAR appointments revised. The amendment extends certain procedural timelines, permits UIN grant after Ministry of External Affairs recommendation, requires eligible persons to declare input tax credit entitlement electronically in FORM GST ITC-01 within thirty days (subject to Commissioner extensions), validates FORM GST PMT-06 challans for fifteen days, authorises specified international payment routes for non-resident online suppliers, requires Authority for Advance Ruling members to be officers not below Joint Commissioner, and revises REG-01, REG-13 and TRAN-1 form fields and headings as specified.