Hi

I have been working in the us since 02/08/2008
I was on OPT from 02/08/2008 to 10/01/2008
I am on h1-b since then

My employer did not withheld FICA on my paycheck since 10/01/2008
What are my options?
Do I owe the money to IRS or my employer?
Can I find an agreement with my employer such as a loan or anything like that?

Thanks

First, you need to tell your employer, preferably in writing.

Then you need to let HIM correct the error.

Technically, you owe YOUR half of the FICA taxes, but the employer has to correct the error and pay the resulting fines from the IRS.

Do not be surprised if they just start withholding the taxes retroactive to 1 January 2011 to AVOID those fines. If that happens, there is nothing you can really do about it without risking your job.