Lawful permanent residents or conditional permanent residents who wish to remain outside the United States for more than one year, but less than two years, may apply for a re-entry permit.
There are two functions of a Re-entry Permit:
1. It allows a permanent resident of the U.S. to reenter the U.S. after traveling abroad for longer than one year but less than two years. Usually, if a permanent resident travels abroad for a period longer than one year, s/he faces a risk of denial of admission into the U.S. on the ground that s/he has abandoned his or her permanent resident status. A Re-entry Permit is designed to solve this problem.
2. It serves as a passport for a permanent resident of the U.S. if s/he has no passport and cannot obtain it from the country of his/her nationality.
Please note that an absence of more than one year from the U.S. will sever the 5-year continuous residence period requirement necessary to become a citizen, even if a re-entry permit is obtained.
What is the difference between a Re-entry Permit and an Advanced Parole?
An Advance Parole is issued to an alien who is applying for but does not have permanent resident status, whereas a Re-entry Permit is issued to a permanent resident of the U.S.
On its face, an Advance Parole is a piece of paper with the holder's photo on it, whereas a Re-entry Permit looks similar to a passport. An Advance Parole functions like a visa to the U.S. while a Re-entry Permit functions, occasionally, like a passport.
In other words, an alien with an Advance Parole still needs a foreign passport to enter the U.S,. while a permanent resident with a Re-entry Permit does not need a foreign passport to get into the U.S. Another difference is the duration: An Advance Parole is valid for one year, whereas a Re-entry Permit is valid for two years