Hi,
I have been in the US for the past couple of years as a student on F1 visa. Last year my spouse joined me on F2 visa. I have graduated recently, and have been working on my OPT (while still on F1 & F2 respectively).

My H-1B visa has been approved recently (approval date May 2006, valid from October, 2006). Similarly, my spouse's H4 visa has also been approved with the same approval and validity dates. Also, my spouse does not have a job.

It seems that so far I have been exempt from Social Security & Medicare taxes. However now I am non-exempt from the "date of approval" of my H-1B visa. Also, on my W4 I have been filing taxes as "Single" since my wife was a non-resident alien and not working

My questions are:
- Should I update my W4 so that we can file as "married"? If yes, when should I update it? Should I update it right now (from the date of approval), or should I update it in October.

- Also, I heard that since my spouse is on H4 visa now, I need to apply for a Tax (ITIN) number for my spouse? I am not really sure what that means. Do I need to do that even when we are filing taxes jointly? How do I apply for ITIN number? Do I need an ITIN number too? (I have a social security number).

Thank you for your time & assistance.

1) You CAN update the W-4, but that's not really important, as the W-4 only specifies how much is withheld, NOT the final filing status.

2) Your wife will need an ITIN, but you apply for that using Form W-7 when you file your 2006 tax return. You do not need an ITIN; your SSN is all you need.