As a permanent resident of the United States you may travel abroad for periods of less than one year and reenter the U.S. with just a valid, unexpired green card. However, you may need to apply for a Reentry Permit in certain situations. There are some things you should know prior to travel after Reentry Permit application.
If you plan to travel for a period of more than one year but less than two years, you must obtain a Reentry Permit. Although you can have the Reentry Permit mailed to an alternate international address or U.S. consulate office, most immigration attorneys recommend that you do not travel until you have received it. If you’ve filed Form I-131, Application for Travel Document, you should avoid departing the United States until the Reentry Permit is granted.
When you file your Form I-131 to obtain a Reentry Permit, USCIS will notify you when to appear for your biometrics appointment. The biometrics appointment must be conducted in the United States. If you leave the United States before you provide your biometrics, USCIS may deny your application.
If you have an extraordinary situation that requires urgent travel, USCIS may grant expedited processing in certain situations.