The United States has tax treaties in place with several foreign nations. Under these international tax treaties, American taxpayers residing in certain foreign countries are taxed at a reduced rate, or are exempt from U.S. taxes on certain items of income they receive from sources within the U.S. These reduced rates and exemptions vary among countries and specific items of income. Under these same treaties, residents or citizens of the United States are taxed at a reduced rate, or are exempt from foreign taxes, on certain items of income they receive from sources within foreign countries. Most income tax treaties contain what is known as a "saving clause" which prevents a citizen or resident of the United States from using the provisions of a tax treaty in order to avoid taxation of U.S. source income.
If the treaty does not cover a particular kind of income, or if there is no treaty between your country and the United States, you must pay tax on the income in the same way and at the same rates shown in the instructions for the applicable U.S. tax return.