26 U.S.C. § 8023

(a) Securing of data The Joint Committee or the Chief of Staff of the Joint Committee, upon approval of the Chairman or Vice Chairman, is authorized to secure directly from the Internal Revenue Service, or the office of the Chief Counsel for the Internal Revenue Service, or directly from any executive department, board, bureau, agency, independent establishment, or instrumentality of the Government, information, suggestions, rulings, data, estimates, and statistics, for the purpose of making investigations, reports, and studies relating to internal revenue taxation. In the investigation by the Joint Committee on Taxation of the administration of the internal revenue taxes by the Internal Revenue Service, the Chief of Staff of the Joint Committee on Taxation is authorized to secure directly from the Internal Revenue Service such tax returns, or copies of tax returns, and other relevant information, as the Chief of Staff deems necessary for such investigation, and the Internal Revenue Service is authorized and directed to furnish such tax returns and information to the Chief of Staff together with a brief report, with respect to each return, as to any action taken or proposed to be taken by the Service as a result of any audit of the return. (b) Furnishing of data The Internal Revenue Service, the office of the Chief Counsel for the Internal Revenue Service, executive departments, boards, bureaus, agencies, independent establishments, and instrumentalities are authorized and directed to furnish such information, suggestions, rulings, data, estimates, and statistics directly to the Joint Committee or to the Chief of Staff of the Joint Committee, upon request made pursuant to this section. (c) Application of subsections (a) and (b) Subsections (a) and (b) shall be applied in accordance with their provisions without regard to any reorganization plan becoming effective on, before, or after the date of the enactment of this subsection.