4 U.S.C.
§114. Limitation on State income taxation of certain pension income
(a) No State may impose an income tax on any retirement income of an individual who is not a resident or domiciliary of such State (as determined under the laws of such State).

(b) For purposes of this section—

(1) The term "retirement income" means any income from—
. . .
(E) an individual retirement plan described in section 7701(a)(37) of such Code;