Lawful Permanent Residents, although free to travel abroad, are subject to certain restrictions upon reentering the United States. As a Permanent Resident, a trip abroad that is too long or multiple trips that are too frequent, may lead to a finding that you have “abandoned” your permanent residency. Abandonment can have several negative effects on your ability to remain in the U.S. Not only can you be denied reentry upon return from a trip abroad, but you may also disrupt the continuity and duration of residency required for naturalization.
If you plan to be outside the U.S. for more than a year, you may need to apply for a Reentry Permit. The Reentry Permit does not necessarily guarantee that you will be admitted to the U.S. upon reentry (as you may be inadmissible for other reasons), but it does tell the immigration authorities that you did not intend to abandon your permanent residency when you left the U.S. This is important if you wish to maintain your permanent resident status.