Return information disclosed under this paragraph includes the taxpayer identity information (as defined in section 6103(b)(6)) of the plan or trust, the name and address of the sponsor and administrator of the plan or trustee of the trust, and the name and address of the person authorized to represent the plan or trust before the Service. Disclosure of returns or return information as provided by this paragraph will be made only following receipt by the Commissioner of Internal Revenue or his delegate of an annual written request for such disclosure by the Secretary of Labor or his delegate or the Executive Director of the Pension Benefit Guaranty Corporation or his delegate describing the categories of returns or return information to be disclosed by the Service and the particular purpose for which the returns or return information is needed in the administration of title I or IV of the Act, and designating by title the officers and employees of the Department of Labor or such corporation to whom such disclosure is authorized.
Disclosure of a return or return information to a person other than the taxpayer to whom such return or return information relates (or the legal representative of such taxpayer) to properly accomplish any purpose or activity described in this subparagraph should be made, however, only if such purpose or activity cannot otherwise properly be accomplished without making such disclosure.
Disclosure of returns or return information to other persons by officers and employees of the Department of Labor or the Pension Benefit Guaranty Corporation as provided by subparagraph (2)(ii) of this paragraph for purposes of conducting research, surveys, studies, and publications referred to in section 513(a), or authorized by title IV, of the Act shall be restricted, however, to disclosure to other officers and employees of such department or corporation to whom such disclosure is necessary in connection with such conduct or to the taxpayer by whom such return was made or to whom such return information relates if the return or return information can be associated with, or otherwise identify, directly or indirectly, a particular taxpayer.
26 C.F.R. §301.6103(l)(2)-3
Secs. 6103 and 7805 of the Internal Revenue Code of 1954 (90 Stat. 1667, 1685, 68A Stat. 917; 26 U.S.C. 6103 and 7805 )