A re-entry permit is a travel document. It enables a Green Card holder to confirm his status as Permanent Resident or Conditional Resident
- for long periods of absence outside the United States (more than one year), or
- when taking up a new residence outside the United States (also in case of absence of less than one year)
to maintain.
A re-entry permit must be applied for using Form I-131 (Application for Travel Document) well in advance of the planned departure.
The re-entry permit is issued by the U.S. Citizenship and Immigration Services (USCIS) and has a blue-green booklet similar to a U.S. passport.