回复：多谢高人阿！所以绿卡是离开美国一年内返回都没有问题吗？

果他现在放弃绿卡的话可以明年不用交美国税了吗？

-Not need to pay the tax to US IRS if he plan to give up the green card.

在那里可以找到更多关于放弃美国绿卡？

-Provide the completed I-407 and the green card to the US Embassy/Consulate in China. That is all. He can apply for the non-immigration visa to visit US such as B2 with multiple entry and valid for 5 or 10 years.

有什么坏处？

-Can not have the green card benefit anymore.