GST rule amendment: procedural timelines, registration forms, payment routes and claiming of input tax credit revised. The amendment revises timelines and procedures under the Bihar GST Rules, extending prescribed periods and substituting time limits for declarations to claim input tax credit. It permits electronic submission of returns in FORM GSTR-3B under conditions where filing deadlines for GSTR-1 and GSTR-2 are extended, updates registration and UIN application forms and instructions for UN bodies and embassies, allows alternative electronic and international payment routes for certain overseas suppliers, and requires appointment of senior officers as members of the Authority for Advance Ruling.