Income tax the discussion of taxation by the United States of foreign persons. Residents, however, are generally subject to income tax on all worldwide income. A very few countries (notably Singapore and Hong Kong) tax residents only on income earned in or remitted to the country. Residence is often defined for individuals as presence in the country for more than 183 days. Most countries base residence of entities on either place of organization or place of management and control. The United Kingdom has three levels of residence. Most systems define income subject to tax broadly for residents, but tax nonresidents only on
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