I was on F1 Visa and I was on OPT on 2011. I got my married, change my status on Dec 2011. So, how can I fill join tax with my spouse. And do I eligibility for tax return ( medicare and social sercurity) on my OPT which my employer did withheld on my paycheck 2011?

For 5 years on F1/OPT you are nonresident and must file nonresident tax return and Form 8843. You do not pay Medicare and social security taxes. You can not file joint return as residents. Your U.S. Tax Return: Social Security and Medicare (FICA) Taxes for Non-resident Exempt Individual (http://taxipay.blogspot.com/2008/03/non-resident-exempt-individual-social.html)

Emily:

What MukatA says is accurate IF you married another non-resident alien.

However, if you married a U.S. resident or U.S. citizen, then you CAN file jointly with him and CHOOSE to be treated as a resident alien for all of 2012. This will NOT affect your exemption from FICA (Social Security and Medicare) taxes, but MAKE SURE that your employer is NOT withholding these FICA taxes before you file.

If you need professional help, double click on my title above, then scroll down to the bottom of the page where my signature block is located. My email address in in my signature block.

Thanks a lot for your answer, MukatA and Atlanta TaxExpert.
I want to explain more about my case.
I came to U.S on May 2006 as F-1 visa.
On Jan 2011 I got my OPT. I start working from May 2011 under OPT program.
On April 2011, I got married to a U.S citizen guy.
On Nov 28, 2011 my green card had been approved.
I got my W2 and it stated my social number instead of my alien number.
So my question is:
Can I still eligible to file form 1040 NR-EZ, 843 and 8316 to obtain a refund from the IRS for the Social Security and Medicare taxes which was withhold in error by my employer? If yes, is anything I have to do with my employer before filling the form?
Or it better for me to join tax with my spouse ?

You are nonresident form 2006 to 2010. In 2011, you must pay Medicare and Social Security taxes. You must file resident tax return for 2011.

MukatA is correct.

Regardless of whether you file JOINTLY with your husband or file Married Filing Separately, you WILL file as a resident, filing Forms 1040, 1040A or 1040EZ.

Most likely, you get the best tax breaks if you file jointly with your husband, but you should model it BOTH ways to be sure.

You became liable for FICA (Social Security and Medicare) taxes on 1 January 2011, so there is NOTHING to be gained by filing as a non-resident alien even if it WAS possible, which it is NOT.

If you want my professional help, double-click on my title above and scroll down to my profile/signature. You will find my email address there.