The United States Tax System is based on worldwide income not just domestic income, thus the same rules for filing a tax return apply to U.S. Expatriates as well.
Whether an expatriate has to file a U.S. tax return depends on the amount of the expatriate’s taxable income. If an expatriate’s taxable income exceeds his/her standard deduction and exemption then the expatriate is required to file a tax return. If an expatriate works in a country that has a Totalization agreement with the Social Security Administration then the expatriate must file a tax return to report information even if his/her taxable income is below his/her standard deduction and exemption.
An expatriate must file a tax return to claim the foreign income exclusion or a tax credit for foreign taxes paid, it is not automatic.
Please do not hesitate to contact us if you have any questions about filing a tax return.