Tex. Tax Code § 151.008

Sec. 151.008. "SELLER" OR "RETAILER". (a) "Seller" or "retailer" means a person engaged in the business of making sales of taxable items of a kind the receipts from the sale of which are included in the measure of the sales or use tax imposed by this chapter.

(b) "Seller" and "retailer" include:

(1) a person in the business of making sales at auction of tangible personal property owned by the person or by another;

(2) a person who makes more than two sales of taxable items during a 12-month period, including sales made in the capacity of an assignee for the benefit of creditors or receiver or trustee in bankruptcy;

(3) a person regarded by the comptroller as a seller or retailer under Section 151.024;

(4) a hotel, motel, or owner or lessor of an office or residential building or development that contracts and pays for telecommunications services for resale to guests or tenants;

(5) a person who engages in regular or systematic solicitation of sales of taxable items in this state by the distribution of catalogs, periodicals, advertising flyers, or other advertising, by means of print, radio, or television media, or by mail, telegraphy, telephone, computer data base, cable, optic, microwave, or other communication system for the purpose of effecting sales of taxable items;

(6) a person who, under an agreement with another person, is:

(A) entrusted with possession of tangible personal property with respect to which the other person has title or another ownership interest; and

(B) authorized to sell, lease, or rent the property without additional action by the person having title to or another ownership interest in the property; and

(7) a person who is a marketplace provider under Section 151.0242.