26 CFR § 1.531-1 - Imposition of tax.
Section 531 imposes (in addition to the other taxes imposed upon corporations by chapter 1 of the Code) a graduated tax on the accumulated taxable income of every corporation described in section 532 and § 1.532-1. In the case of an affiliated group which makes or is required to make a consolidated return see § 1.1502-43. All of the taxes on corporations under chapter 1 of the Code are treated as one tax for purposes of assessment, collection, payment, period of limitations, etc. See section 535 and §§ 1.535-1, 1.535-2, and 1.535-3 for the definition and determination of accumulated taxable income.