Permanent or conditional residents should apply for a Re-entry Permit if they plan to be outside the United States for one year or longer. It allows applying for admission to the United States upon returning from abroad, without having to obtain a returning resident visa.
As a rule, a Re-entry Permit issued to a lawful permanent resident is valid for 2 years from the date of its issuance. But if an applicant has been outside the USA for more than 4 of the last 5 years since becoming a lawful permanent resident, USCIS will issue a Re-entry Permit valid for 1 year only. Except for the following categories of applicants who may still receive a permit valid for 2 years, as they have to travel a lot:
– a lawful permanent resident employed by a public international organization, and the USA is a member of this organization;
– a lawful permanent resident whose travel is on the instructions of the U.S. Government (other than deportation, removal, exclusion, or rescission order);
– a lawful permanent resident who is a professional athlete and he/she regularly competes in the USA and worldwide.
As for a conditional permanent resident, his/her Re-entry Permit is valid for 2 years from the date of its issuance, or to the date when the conditional permanent resident must apply for removal of the conditions on his/her status, whichever date comes first.
Please note that a Re-entry Permit cannot be extended or renewed. You will have to apply for a new one by filing Form I-131 again.