Delegate

(A) In general The term “or his delegate”— (i) when used with reference to the Secretary of the Treasury, means any officer, employee, or agency of the Treasury Department duly authorized by the Secretary of the Treasury directly, or indirectly by one or more redelegations of authority, to perform the function mentioned or described in the context; and (ii) when used with reference to any other official of the United States, shall be similarly construed.

(B) Performance of certain functions in Guam or American Samoa The term “delegate,” in relation to the performance of functions in Guam or American Samoa with respect to the taxes imposed by chapters 1, 2, and 21, also includes any officer or employee of any other department or agency of the United States, or of any possession thereof, duly authorized by the Secretary (directly, or indirectly by one or more redelegations of authority) to perform such functions.