I'm on H1B visa since March 1st 2007. My employer didn't deduct FICA till now. I am not aware of these taxes before. I asked them about it today. They said that they'll deduct from March 1st onwards. On the day of joining itself, I've given them details about my visa status and filled w4.

Will I have a problem in filing my tax returns for 2007? The amount shown in Medicare and Social Security is Nil. Can I file my tax returns in the month of March ? Do I have to pay any other amount as penalty? Or do I have to wait for my April pay check before filing returns?

Thanks for your help.

If you properly informed your employer of your visa status, then you fulfilled your legal obligation.

The IRS will hold the EMPLOYER responsible for these taxes, NOT you.