How to Keep the Card

Travel Outside the U.S.

Permanent Residents are free to travel outside the U.S. However your Green Card can be in danger when you are absent for more than a year.
Abandonment of your Resident Status is assumed when you give the impression that you did not intend to make the U.S. your country of permanent residence.
A CBP Officer may consider criteria such as whether your visit abroad was intended only temporarily, whether you maintained U.S. family and community ties, U.S employment, filed U.S. income taxes as a resident, etc.
Other factors that can be taken into consideration: a U.S. mailing address, U.S. bank accounts, a valid U.S. driver’s license, U.S. property, a U.S. business, etc.

Re-Entry Permit

You need to be absent for one year or longer you must apply with USCIS for a Re-Entry Permit. This permit is called a Travel Authorization or Advance Parole. To obtain it you must file Form I-131. The filing fee form I-131 is currently $575.

New Biometrics (fingerprints/photograph) are then required. When USCIS has accepted your I-131 Application it will set an appointment for you at a USCIS Application Support Center. You will receive a Notification with the location and the date/time of the appointment. The fee for Biometrics is $85.
Biometrics is not needed for applicants younger than 14 and for applicants older than 80 years of age.

Returning Resident

If you remain abroad for more than two years any Re-Entry Permit granted before departure will have expired. In that case you must apply for a Returning Resident Visa SB-1 at a U.S. Embassy or Consulate. An SB-1 Applicant is required to re-establish eligibility for an Immigrant Visa and needs to undergo the Medical Examination again.