Section 45IAC2.2-5-53. Interstate commerce; sales

   (a) The state gross retail tax shall not apply to such part of the gross income from transactions constituting selling at retail as is exempt from the gross income tax under the provisions of IC 6-2.1-3-3.

  (b) Gross receipts derived from transactions which constitute "retail transactions" which the state of Indiana is prohibited from taxing by the Constitution of the United States of America are exempt from gross retail tax. Under this regulation [45 IAC 2.2], this exemption is limited to gross receipts from transactions conducted in commerce between Indiana and other states of the United States, or between Indiana and foreign countries. Such sales commonly are referred to as "sales in interstate commerce" and Indiana is prohibited from taxing such sales by the United States Constitution. (Department of State Revenue; Ch. 5, Reg. 6-2.5-5-24(b)(010); filed Dec 1, 1982, 10:35 am: 6 IR 51)