回複：請問綠卡回國能不能超過半年？ 謝謝

If you have green card and leave the US, when you come back, the immigration officer need to make a determination whether you still have the intention to permanently reside in the US. According to the law, if you leave US less than 6 months, then there is a presumption that you still have such an intention. That means, INS won't make any trouble for you. But if it's more than half a year, the presumption does not apply and they have to redetermine your intention. So there is no legal requirement that you have to come back within half a year, but there are certain risk in not doing so.