Hi,

I came to US on H1B visa during November,2009. My wife and kid were in India during that time, I filed my Federal tax return as single for 2009. My family joined me in US during May,2010, my question is am I eligible to claim tax credit being married with a kid ?

Nsk

QUOTE,"I came to US on H1B visa during November,2009."----Actually, you entered the US after July 2nd of 2009.So, you couldn't meet the Substantial Presence Test and must have filed as a non-resident alien,( as a single, 1040nr/1040nr-ez for 2009) but also still MAY have been able to file a dual-status tax return under the First Year Choice rule( if you had met the requirements under the rule). However, as you were married( though she and your kid were in India in2009), you were able to choose to be treated as resident aliens, regardless of whether you entered the United States before or after July 3rd as long as you met the First Year Choice rule and filed the First year choice statement in 2009. If you had satisifed all the requirements for passing the First Year Choice option in 2009, then in 2010, you can file amended return to claim your residencyas resident aliens in 2009.
"My family joined me in US during May,2010, my question is am I eligible to claim tax credit being married with a kid ?"---- As you have already met SPT in 2010, then you can file joint return as regular residents. On your resident tax return, you can also claim exemption for dependents just like the U.S. citizens and residents, however, you must report your worldwide income( if you have) for the year.
On your joint return with your wife, it is not required that your spouse must be a resident of the U.S. If your spouse can not get SSN, then you will attach W7, ITIN application,with your tax return. Also for a dependent, who can not get SSN, you will attach W7 Form.