A Letter of Authorization for GST is an important document to share power. Enter on line 7 any state and local general sales taxes paid on the following specified items.For Collin County Motor Vehicle Transactions. What's the Right Way to Structure a GST Authority Letter? Telephony Designator Assignment. 1-4-1. For Collin County Motor Vehicle Transactions. This application for authorisation may also be expressed to be made in relation to other contracts, arrangements or understandings or proposed contracts,. A6.6 Letter of authorisation. It is a commitment I made myself during the election campaign, in a letter, and one I intend to keep.