Income tax in the United States under tax treaties. Foreign persons are taxed on income from a U.S. business and gains on U.S. realty similarly to U.S. persons. Nonresident aliens who are present in the United States for a period of 183 days in a given year are subject to U.S. capital gains tax on certain net capital gains realized during that year from sources within the United States. The states tax non-resident individuals only on income earned within the state (wages, etc.), and tax individuals and corporations on business income apportioned to the state. The United States has income tax treaties with over 65 countries.
Income tax in the United States on saved income is itself taxed. To the extent that this is considered unjust, it may be remedied in a variety of ways, e.g. excluding investment income from taxable income, making investments deductible and therefore only taxing them when gains are realized, or replacing the income tax by other forms of tax, such as a sales tax. Some economists believe income taxation offers the federal government a technique to diminish the power of the states, because the federal government is then able to distribute funding to states with conditions attached, often giving the states no choice but to submit to