IRS PUBLICATION 519 - U.S. TAX GUIDE FOR ALIENS

A document that outlines the tax procedures for aliens, individuals that are not American citizens. Not all aliens are subject to US taxes. Aliens are categorized as resident aliens and nonresident aliens. Resident aliens, who have been in the US for a specified time period, are taxed on their worldwide income just as citizens are. Nonresident aliens are only taxed on income earned within the US and on certain income related to the conduct of a trade or business in America.