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.