Currently, I am working as f-1 opt, and I have been in America for over 5 years since 2006, so I filed tax return by 1040. My question is: my employer should can charge me SS/Med Tax, regadless I am in f-1 opt, because I have been seen as resident alien. Thank you.

If you arrived in the U.S. in 2001 or earlier on your F-1 visa, your exemption from Social Security and Medicare taxes expired on 31 December 2005.

So, yes, in 2006, you SHOULD have paid these taxes regardless of your F-1 visa status.

However, it is the EMPLOYER's responsibility to make that determination, NOT YOURS!

Unless you actively attempted to hide the fact that you had been in the U.S. for longer than five years, the IRS will not hold you responsible for these taxes.

Recommend you tell your employer that you should be paying these taxes, and make arrangements to back back taxes from 1 January 2007 onward.

It is too late for the employer to legally collect the back taxes for 2006, nor do I think they will want to pursue the issue, as the IRS will levy a huge fine on the employer once they determine that they failed to withhold and pay the tax in a timely manner.

Thank you.

Glad to help!