A. Except as otherwise provided in this section, exempted from the gross receipts tax are receipts of:

(1)     the United States or any agency, department or instrumentality thereof; (2)     the state of New Mexico or any political subdivision thereof;

(3)     any Indian nation, tribe or pueblo from activities or transactions occurring on its sovereign territory; or

(4)     any foreign nation or agency, instrumentality or political subdivision thereof, but only when required by a treaty in force to which the United States is a party.

B. Receipts from the sale of gas or electricity by a utility owned or operated by a county, municipality or other political subdivision of a state are not exempted from the gross receipts tax.

C. Receipts from the operation of a cable television system owned or operated by a municipality are not exempted from the gross receipts tax.