Authorisation of state tax officers as proper officers allows joint orders and prevents duplicate proceedings across central and state GST. State or Union territory GST officers may be authorised as proper officers for central GST subject to notification-specified conditions. An officer issuing an order under central GST must, under those conditions, also issue the corresponding State/UT GST order and notify the jurisdictional State/UT officer. Where a State/UT officer has initiated proceedings on a subject matter, central GST proceedings on that subject are barred. Rectification, appeal and revision of orders by central GST officers are not maintainable before State/UT GST officers.