Hello

I arrived in the US on a J-1 visa in March of 2011, then in Sept 2011 that changed from a J-1 to a H-1B Visa.
Therefore I have been in the US for more than 183 days in 2011 in total, but have not been here for more than 183 days while on a H-1 visa.
I'm not sure what my status is and what form I should use to file my tax return?

(I'm married and my wife has been in the US since Sept 2011 on a H4 visa, she has had no income).

Thank you.

P.S. I was working at the same company while on both the J-1 and H-1 and receiving income, while on the J-1 it would be considered a "stipend", while on the H-1 it is regular income.

On H-1B you did not complete SPT so you are nonresident. You have three choices:
1. File nonresident tax return,
2. File dual status tax return after you complete SPT in 2012, or
3. File joint return as residents after you complete SPT in 2012. Your U.S. Tax Return: Substantial Presence Test (http://taxipay.blogspot.com/2008/04/substantial-presence-test.html)

Thanks, so to clarify - SPT is not based upon the total number of days I have been physically present in the US, but the number of days present since I changed to the H-1?

As I got the H-1B in September (September 30th), by the time the filing deadline is here then 183 days will have passed. Is there any advantage/disadvantage in choosing option 1) or option 2)?

(I've read that I cannot do a joint filing as my wife doesn't have an SSN nor a ITIN, and as she isn't eligible to work she can't apply for one either, so option 3 can't be applicable)

Thanks, so to clarify - SPT is not not based upon the total number of days I have been physically present in the US, but the number of days present since I changed to the H-1?

SPT *is* generally based on the total number of days you have been physically present in the US. However (if you look further in the instructions), a teacher or trainee under J visa is exempt from the SPT for the first two years. You need to file Form 8843 to justify excluding the days while you were on the J visa.

Days on J1 are exempt from residency so only days on H1-B are counted for SPT. Choice 1 and 2 result is same tax so it is better use choice 1.
Choice 3 is applicable, you can use it. A U.S. citizen or resident can file joint return as residents even when the spouse has never been to U.S. Both must report worldwide income for the year. Attach W-7 (ITIN application) with your tax return.

Thanks to both for the answers.

As my wife had no income (either in the US or worldwide) in 2011, can or should I still file a joint return?

Yes.