QUOTE(alohafromkona @ May 13 2008, 12:10 AM)

I have wondered about this too. I was married in November, and I filed taxes as single. I am still listed as single.
I was told by someone in HR at work that I wouldn't add her to insurance etc. until she had her visa, and SS#. Until then, I should remain single.
I dont know if this is true or not, but I havent looked further into it.
You will need to amend your return. If you were married in November you must file as married (as married filing jointly or married filing separately). If she has no SS# you would need to follow the procedure to request an ITIN. Filing your taxes has nothing to do with how you are set up at work or whether or not you can add her to your insurance. You cannot file as single if you are not single.
As far as the stimulus check, you will need to contact the IRS. You might just have to declare it on next year's return, or it may depend on whether your wife will have her SS# by then, but they should hopefully be able to guide you on how to rectify that or you might check the FAQs on the irs.gov site. If it hasn't been submitted to you yet they might be able to cancel it if you contact them right away.
Also, once your wife obtains an ITIN it may be acceptable to your employer so you can add her to your insurance, etc. The number is formatted just like a SS# but you might explain it's an ITIN so they can confirm if it can be accepted. Each employer is different on how they handle that.
PJ