Pattu Rani,
When you file your 2007 taxes, you must file as married since you were married at the end of 2007. You have the choice of 2 filing statuses, "Married filing jointly" or "married filing separately". Which choice you make there depends on your particular situation. If your hubby made lots of money in Nepal, then you wouldn't want that taxed in the US, so you would go Married filing separately (he would not be required to file since he is not a US Resident for tax purposes).
If your husband made little to no money, then you will probably benefit by filing jointly as it will give you a bigger return. Now, to file jointly, since your hubby doesn''t have an SSN, what you do is fill out your appropriate tax return form (1040) and a W-7 (Application for IRS Individual Taxpayer Identification Number). Attach the W-7 to the 1040 and sent it to the IRS Austin Service Center (oh no, another service center) to ITIN Operations. They will issue an ITIN for your hubby and process the return. The attached return is now required to insure that people just aren't randomly requesting unneeded ITINs.
As for the W-4 at work, that only has to do with withholdings. It doesn't really matter, you can leave it as it is, and you will get a bigger return or owe less money if you owe money. Change it to include your hubby and you will have less withheld so you will get a smaller return. Some people claim extra exemptions because they don't want the gov't holding their money interest free until return time, then they owe money on April 15th. In this case, they are getting the interest free loan until April 15. This strategy comes with the risk of being too short for 2 consecutive years, which can result in penalties. Others who cannot save money on their own and want to see a big return because it makes it easier to put some aside will claim fewer exemptions then they are allowed to bolster their return. Bottom line is that this is not all that important as in nothing is really required to be done. You might make some choices here based on other factors, desires, and circumstances.
QUOTE(Pattu Rani @ Dec 21 2007, 07:33 AM)

I am wondering if I need to go to my HR office and change my W-4 forms now that I am married, or if I only change filing status from "Single' to 'Married, filing separately' when I fill out my tax return. What did other people do?