For provisions concerning the period covered by returns or other documents, see the regulations relating to the particular tax.
The preliminary Code is a preliminary release of the Internal Revenue Code of 1986 (the "Code") by the Office of the Law Revision Counsel and is subject to further revision before it is released again as a final version. The source of the preliminary Code used in TouchTax is available here: https://uscode.house.gov/download/download.shtml. The Code is a consolidation and codification by subject matter of the general and permanent laws of the U.S. prepared by the Office of the Law Revision Counsel of the U.S. House of Representatives. The Treasury Regulations are a codification of the general and permanent rules published in the Federal Register by the departments and agencies of the federal government. The version of the Treasury Regulations available within TouchTax is part of the Electronic Code of Federal Regulations which is not an official legal edition of the Code of Federal Regulations but is an editorial compilation of CFR material and Federal Register amendments produced by the National Archives and Records Administration's Office of the Federal Register (OFR) and the Government Publishing Office. The source of the CFR used in TouchTax is available here: https://www.govinfo.gov/bulkdata/ECFR/title-26. Those using TouchTax for legal research should verify their results against the printed versions of the Code and Treasury Regulations. TouchTax is copyright 2022 by Com-Lab (Mobile). Learn more at http://touchtax.edrich.de.