The United States is known as an inclusive country. People from all over the world study, work and live in this country. As an international student or foreign worker, you may ask the question, what is my US tax status when I have income. Below I will give you a starting point when you ask this question or struggle with this issue.
The first step in resolving this tax problem is to understand if you are a resident alien or a non-resident alien. As for tax purposes, an alien refers to an individual who is not a U.S. citizen. Alien has two subcategories, resident alien and non-resident alien. In most cases, resident aliens are taxed on all their income, regardless where the income comes from. Nonresident aliens are taxed only on income sources from within the United States, and on most income which is from a trade or business in the United States. Often, foreign people may also subject to certain tax treaties as well that can override the regular tax rules.
Normally, you are nonresident alien unless you pass either green card test or substantial presence test for the calendar year. The green card test means you meet the test as a lawful permanent resident of the United States. You are regarded as a lawful resident if you are given privilege to reside in the United States permanently as an immigrant. Often, governmental agency (i.e. USCIS) will issue you a registration card when you have this status. This status continues unless the resident status is taken away from you (administratively or judicially). A green card holder pays taxes, and is subject to the same tax rules, as a US citizen