Hi,
The whole 2011, my Employer by mistake did not cut my FICA taxes after my status changed from F2 to H1B. They still were considering me on F2 by mistake. Later this year when they realized this, they issued me corrected W2 for 2011 and are asking me to pay the whole year FICA tax to them as they are claiming they paid it. So should I pay them? The other thing I am wondering is that when I filed the tax return for 2011, did IRS cut that tax or not already? What should I do?

Thanks.

You DO have the moral obligation to pay your share of this tax. Mistakes happen, and they are only asking that you pay YOUR share of the tax.

Note that when they corrected this error, they likely paid a rather HEFTY fine for making the mistake. As long as they do not expect you to pay any of the fine or interest that the IRS charged, make arrangements to pay the 2011 taxes.

Legally, they have NO leg to stand on to require you to pay the 2011 tax. However, to avoid paying the tax, you would have to quit your job. That MIGHT be a bit drastic to save a few thousand in taxes.