Income tax in the United States income taxes. This foreign tax credit is limited to that part of current year tax caused by foreign source income. Determining such part involves determining the source of income and allocating and apportioning deductions to that income. States tax resident individuals and corporations on their worldwide income, but few allow a credit for foreign taxes. In addition, Federal income tax may be imposed on non-resident non-citizens, including corporations, on U.S. source income. Federal tax applies to interest, dividends, royalties, and certain other income of nonresident aliens and foreign corporations at a flat rate of 30%. This rate is often reduced
Income tax in the United States insurance (Social Security) taxes in 2016. The table below also does not reflect changes, effective with 2013 law, which increased the average tax paid by the top 1% to the highest levels since 1979, at an effective rate of 33%, while most other taxpayers have remained near the lowest levels since 1979. Income tax is imposed as a tax rate times taxable income. Taxable income is defined as gross income less allowable deductions. Taxable income as determined for federal tax purposes may be modified for state tax purposes. The Internal Revenue Code states that "gross income means all income from