My parents had problems getting nonimmigrant visas, so I had to apply for them green cards so that they can visit me. I've read and heard a lot of conflicting information regarding the residency requirement in the US. On the USCIS website it says a reentry permit is required for absences from the US for over a year. But on this forum most posts say do not let that exceed 6 months. My question is, if my parents don't want to apply for citizenship eventually, can they stay in the US for 3 months, leave for 5 months, come back for 3 months, and keep doing that and keep their GCs? In other words, they'd be away for more than 6 months in a consecutive 12 months period, but each trip does not exceed 6 months and they'd stay in the US for minimum of three consecutive months out of a 12 month period. I understand coming back to stay for a couple of weeks is problematic, but how long is long enough? Does it have to be 6 months at a time?