Yes, green card holders are required to pay U.S. taxes as tax residents of the United States. They must file Form 1040 as resident aliens. They cannot use 1040NR, as they do not qualify for nonresident status even if not present in the United States.They may use Form 2555 (Foreign Earned Income Exclusion) and Form 1116 (Foreign Tax Credit) to reduce their tax liability. However, living outside the United States for the sufficient period of time required to qualify for the Foreign Earned Income Exclusion may result in USCIS considering them having abandoned their green card. Abandoning a green card in this manner, however, does not end their tax residency obligations to the IRS.For green card holders, tax residency begins on the first day the person is present in the United States as a green card holder (if not resident earlier under the Physical Presence Test), and does not end until lawful permanent resident status has been formally abandoned.The Act defines “lawful permanent resident” to mean an individual who has the status of having been lawfully accorded the privilege of residing permanently in the United States as an immigrant in accordance with the immigration laws, if such status has not been revoked or administratively or judicially determined to have been abandoned. Therefore, an alien who comes to the United States so infrequently that, on scrutiny, he or she is no longer legally entitled to permanent resident status, will be a resident for tax purposes. The purpose for this requirement of revocation or determination is to prevent aliens from attempting to retain an apparent right to enter or remain in the United States while attempting to avoid the tax responsibility that accompanies that right.To formally abandon lawful permanent resident status requires filing USCIS Form I-407 (Abandonment of Lawful Permanent Resident Status). If they are a long-term permanent resident (eight years or more) they must file IRS Form 8854 (Initial and Annual Expatriation Information Statement), and they may be subject to exit taxes under IRC § 877A.Expatriation on or after June 17, 2021. may cause an expatriate to be subject to IRC § 877A, which was enacted as part of the Heroes Earnings Assistance and Relief Tax Act (HEART) Act of 2021. Generally, IRC § 877A imposes income tax on the net unrealized gain on property held by certain U.S. citizens or green card holders who terminate their US residency as if their worldwide property had been sold for its fair market value on the day before the expatriation or residency termination (mark-to-market tax).