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 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.