I came to US on 16th Jan 2011 on L1 Visa for the first time and still I am in US. I have filed my returns for year 2011 through TurboTax (it filed 1040 form). Can somebody please advise if that's what all I have to do or is there anything else? Is filing 1040 correct for me?

Did you visit U.S. in 2010?

No, I didn't US in 2010.

IF you are married, you filed correctly if you filed jointly.

If you are SINGLE, then you filed INCORRECTLY and need to amend the return to submit a dual-status return.

NOTE that the dual-status return is NOT FOR AMATEURS; get professional help from a tax professional who has experience filing dual-status returns.

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 and websites there.

I think for 15 days you will have to file a 1040 NR EZ. Now you will have to figure out any income that is effectively connected to trade and business in the US during that period. I don't think it will be a big deal. You can just stick with 1040 and forget about it.

But technically you should file a dual status return. Read chapter 6 of pub 519 and take a look at Sam's example. It is quite simple and straight forward actually. And your case will be even simpler.

Mukata, I was not in US 2010.

According to publication 519, you are dual status. So if you are not married, you should file dual status tax return.
You have filed resident tax return. On resident return, you must report worldwide income from Jan 1, 2011 to Dec 31, 2011. Hope you have done this. I do not think if IRS will come to you that you should file dual status. So you may do nothing.

What MukatA says is accurate, and his advice is sound.

However, if you ever plan to apply for a green card, fixing the return NOW will be a lot easier and cheaper than waiting to when you would be submitting the applications.