Requests filled out for the drop box are generally received and begin the process for authentication within one business day. Mailing and Physical Address:.A Letter of Authorization for GST is an important document to share power. Attach a copy of the determination letter from the IRS qualifying your organization as exempt from tax under Section 501(c)(3) of the Internal Revenue Code. For information and a filing application contact the Salt Lake County Treasurer's Office at: 385 468-8300. 1.1 Director, Sports Authority of India, Netaji Subhas Eastern Centre, Salt Lake City,. V, Salt Lake City, Kolkata 700091. GSTIN. 19AAACT1426A1ZW. In the Contract Cell, CZ HQr, CRPF, H.C. Block, SectorIII,. Salt lake, Kolkata-106 (W.B.). Authority through letter of acceptance.