Switching from J1 to H1B - tax liability
I have been on J1 visa in the U.S. from February 2009 till August 2010 when we left the U.S. Now I have H1B visa and my wife has H4 visa since October 1, 2010. We arrived in the U.S. on October 25, 2010. I have questions regarding my tax liability:
1) under J1 I did not have to pay Social Security and Medicare taxes. As I understand, under H1B visa my employer needs to pay these contributions. Is that correct?
2) As I understand, these contributions must be paid since the validation of my H1B visa which happened not when the visa was valid (October 1, 2010), but when I arrived in the U.S. on October 25, 2010. Is that correct?
3) Under J1 visa, even though I was married, I had to file as single. Can I under H1B file my 2010 taxes in 2011 together with my wife as married? That would help me to offset SS and Medicare contributions taken from my pay. I intend to stay in the U.S. for next 18 months.