4.2.5. Transactions with a significant book-tax difference. A taxpayer has participated in a transaction with a significant book-tax difference if the taxpayer's tax treatment of an item from the transaction differs from the book treatment of that item as described in Treasury Regulations Section 1.6011-4(b)(6) and this rule. In determining whether a transaction results in a significant book-tax difference for a taxpayer, differences that arise solely because a subsidiary of the taxpayer is consolidated with the taxpayer, in whole or in part, for book purposes, but not for tax purposes, are not taken into account: Provided, That transactions with a significant book-tax difference entered into or on January 6, 2006 that do not describe any other reportable transaction in Treasury Regulation Section 1.6011-4, will no longer be classified as reportable transactions: Provided, however, That the removal of such significant book-tax difference transactions from the categories of reportable transactions does not relieve taxpayers, tax shelter organizers, advisors, or any other person from any disclosure, registration or list maintenance obligations for transactions that should have been disclosed or registered, or for transactions for which lists should have been prepared and maintained, prior to January 6, 2006. For purposes of this subsection, the amount of an item for book purposes is determined by applying U.S. generally accepted accounting principles (U.S. GAAP) for worldwide income. However, if a taxpayer, in the ordinary course of its business, keeps books for reporting financial results to shareholders, creditors, or regulators on a basis other than U.S. GAAP, and does not maintain U.S. GAAP books for any purpose, then the taxpayer may determine the amount of a book item for purposes of this subsection by using the books maintained by the taxpayer, provided the books are kept on the same basis consistently from year to year. Adjustments to any reserve for taxes are disregarded for purposes of determining the book-tax difference.
4.2.5.1. In general, this category of reportable transactions applies only to: 4.2.5.1.a. Taxpayers that are reporting companies under the Security Exchange Act of 1934 and are related businesses; or4.2.5.1.b. Business entities that have $250,000,000 or more in gross assets for book purposes at the end of any financial accounting period that ends with or within the entity's taxable year in which the transaction occurs (for purposes of this determination, the assets of all related business entities) must be aggregated.