先直接向employer要refund，如果要不回来再填表，具体方法见下面的IRS网页link：

http://www.irs.gov/businesses/small/international/article/0,,id=104936,00.html

下面是IRS关于F1（CPT，OPT）可免Social Security and Medicare Taxes的说明，可打印出来给employer看。

http://www.irs.gov/businesses/small/international/article/0,,id=129427,00.html