26 CFR § 1.1-2 - Limitation on tax.
(a) Taxable years ending before January 1, 1971. For taxable years ending before January 1, 1971, the tax imposed by section 1 (whether by subsection (a) or subsection (b) thereof) shall not exceed 87 percent of the taxable income for the taxable year. For purposes of determining this limitation the tax under section 1 (a) or (b) and the tax at the 87-percent rate shall each be computed before the allowance of any credits against the tax. Where the alternative tax on capital gains is imposed under section 1201(b), the 87-percent limitation shall apply only to the partial tax computed on the taxable income reduced by 50 percent of the excess of net long-term capital gains over net short-term capital losses. Where, for purposes of computations under the income averaging provisions, section 1201(b) is treated as imposing the alternative tax on capital gains computed under section 1304(e)(2), the 87-percent limitation shall apply only to the tax equal to the tax imposed by section 1, reduced by the amount of the tax imposed by section 1 which is attributable to capital gain net income for the computation year.
(b) Taxable years beginning after December 31, 1970. If, for any taxable year beginning after December 31, 1970, an individual has earned taxable income which exceeds his taxable income as defined by section 1348, the tax imposed by section 1, as amended by the Tax Reform Act of 1969, shall not exceed the sum computed under the provisions of section 1348. For imposition of minimum tax for tax preferences see sections 56 through 58.