Mass. Gen. Laws ch. 62C § 22
The commissioner may permit the Secretary of the Treasury of the United States or his delegate, or the proper tax officer of any territory, state or political subdivision thereof, or any agent or agency designated under the laws of any territory, state or political subdivision thereof to be the representative of such territory, state or political subdivision to inspect any return required to be filed with the commissioner, or may furnish to such officer or his authorized representative an abstract of any such return or supply him with information concerning any item contained in any such return, or disclosed by any investigation of tax liability due under any such return, whether or not filed, but such permission shall be granted or such information furnished to such officer or his representative only if the laws of the United States or of such other territory, state or political subdivision thereof, as the case may be, generally restrict the disclosure of such information except for the purpose of administering tax laws, grant substantially similar privileges to the commissioner and such information is to be used exclusively for the purpose of administering the tax laws of the United States or of such territory, state or political subdivision thereof; and provided further, the commissioner may furnish to the Secretary of the Treasury of the United States or his delegate, or to the proper tax officer of any territory, state or political subdivision or to any agent or agency designated under the laws of any territory, state or political subdivision thereof copies of tax returns filed with him and other tax information, as he may consider proper, for use in court actions or proceedings involving exclusively the administration of the tax laws of the United States, of any territory, or state or any political subdivision thereof, whether civil or criminal, if a written request therefor has been made to the commissioner by the Secretary of the Treasury of the United States or his delegate or by the proper tax officer of any territory, state or political subdivision thereof or of any agent or agency designated under the laws of any territory, state or political subdivision thereof, provided that the laws of the United States or of any territory, state or political subdivision grant substantially similar powers to the Secretary of the Treasury of the United States or his delegate or to the proper tax officer of any territory, state or political subdivision thereof or to any agent or agency designated under the laws of any territory, state or political subdivision thereof. If the commissioner has so authorized use of returns or other information in such actions or proceedings, the commissioner or any employee delegated by him may testify in such actions or proceedings in respect to such returns or other information.
Mass. Gen. Laws ch. 62C, § 22