Income tax in the United States increase complexity, irrespective of the system's flatness or lack thereof. Income tax is also levied by most U.S. states and many localities on individuals, corporations, estates, and trusts. These taxes are in addition to federal income tax and are deductible for federal tax purposes. State and local income tax rates vary from 1% to 16% of taxable income. Some state and local income tax rates are flat (single rate) and some are graduated. State and local definitions of what income is taxable vary highly. Some states incorporate the federal definitions by reference. Taxable income is defined separately and differently for
Legal history of income tax in the United States (1916), the 1913 Act was ruled to be constitutional. A separate excise tax was also imposed on corporations. Subsequent legal actions were concerned with what should be counted as "income" under the 1913 Act. In "Eisner v. Macomber" (1920), the Supreme Court ruled that proportionate stock dividends were not taxable as income, on the grounds that the dividend income was not "severable" from the capital holding from which it was derived. Later decisions, however, have tended to limit this view of "severability," and to uphold the federal statutes as exertions of the power of Congress to tax. The first attempt