(a) Services performed in the employ of any State, or of any political subdivision thereof, are excepted from employment. Services performed in the employ of an instrumentality of one or more States or political subdivisions thereof are excepted if the instrumentality is wholly owned by one or more of the foregoing. Services performed in the employ of an instrumentality of one or more of the several States or political subdivisions thereof which is not wholly owned by one or more of the foregoing are excepted only to the extent that the instrumentality is with respect to such services immune under the Constitution of the United States from the tax imposed by section 3301.

(b) For provisions relating to the term “State” see § 31.3306(j)-1.