"Federal corporate tax returns are confidential and protected from public disclosure under Section 6103 of the Internal Revenue Code (IRC), as enacted by the Tax Reform Act of 1976 (P.L. 94-455). Before 1976, corporate tax returns where classified as part of the 'public record' to varying degrees. Since 1976, there have been occasional calls for the privacy veil to be lifted in response to aggressive tax planning and evasion. This Insight examines several issues surrounding public disclosure of corporate tax returns; however, the discussion below does not address important legal and constitutional issues related to tax return disclosure. When considering the issues discussed below, it is important to note that tax disclosure is not all or nothing. Policymakers may seek a balance between corporate confidentiality and the public's desire to review certain corporate tax information it believes would be informative."
CRS Insight, IN10929
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html