Notwithstanding the provisions of subsection C of this section, the department may permit the commissioner of internal revenue of the United States, or the proper officer of any state imposing an income tax upon the incomes of individuals, or the authorized representative of either such officer, to inspect the income tax returns of any individuals, or may furnish to such officer, or his authorized representative, an abstract of the return of income of any individual, or supply him with information concerning any item of income contained in any return, or disclosed by the report of any investigation of the income or return of income of any individual; but such permission shall be granted, or such information furnished, to such officer or his representative only if the statutes of the United States, or of such other state as the case may be, grant substantially similar privileges to the proper officer of this State charged with the administration of the personal income tax law thereof.
72 P.S. § 3402-506