Lawful permanent residents (LPRs) that depart the US for long periods of time and return once every six months are in danger of losing their resident status. Returning to the US every several months for a few day does not mean that Custom's and Border protection (CBP) will allow a foreign national to keep their resident status. The CBP may find that lawful resident status has been abandoned even if the trip outside the US is a brief trip. Determining if a 'green card' holder has abandoned permanent residency status is not dependent upon only the amount of time spent outside of the U.S.
CBP officers are more interested where a person actually makes residence than the length of time spent outside. The length of time and amount of travel are only some of the factors used by CBP in their determination. Factors include such things as the number of years the person has lived in the U.S.; where the green card holder is employed in the US or abroad; where family members live; and if U.S. income taxes are paid. Certainly, long periods of time more than six months are a strong indicator of residence. If travel is over one year it si presumed residence has been abandoned.
As residence is the principal concern for CBP determinations the traveling resident should be prepared to show evidence of residence. Items such as tax reruns, rent receipt, valid driver's license, and credit card receipts are all examples of evidence.
Some other items that may lead CBP officers to believe the green card holder has given up US resident status include other employment outside the US, immediate family members who live abroad, return on a charter flight particularly when most passengers are non-residents with return ticket abroad, no fixed address in the U.S., or frequent prolonged absences from the U.S.
If undertaking significant travel abroad, whether frequent travel or long periods of travel, it is advisable to obtain a re-entry permit before travel commences. A reentry permit while not conclusive evidence of maintaining lawful resident status, it is another indicator of that the foreign national is maintaining residence in the US.