18-125-325 Me. Code R. § 04
Sales to qualified tribal entities meeting the requirements in this rule shall be exempt from tax, provided that the sale is sourced to a location on tribal land, and that the property or service purchased is not used by the purchaser, including any lessee, primarily outside of tribal land for the first year after the property or service has been placed in service by the purchaser. 36 M.R.S. §1760(114).
The qualified tribal entity must present a copy of its certificate of qualification to the retailer at the time it purchases the property or services that it expects will be used on tribal land and where the sale is sourced to a location on tribal land along with a completed affidavit (Affidavit of Exemption for Tangible Personal Property or Taxable Services Sold to Tribal Member or Tribal Entity - ST-A-133). A separate affidavit is not required for each individual sale.
The retailer must retain a copy of the qualified tribal entity's certificate and affidavit within their customer files. The burden of proving a sale is to a qualified tribal entity is on the person making the sale. The retailer is relieved of this burden of proof if the retailer satisfies the provisions in MRS Rule 18-125, Chapter 302, "Sales to Governmental Agencies and Exempt Organizations."
18-125 C.M.R. ch. 325, § 04