Dear sir/madam,

My wife still living in VietNam and I want ask tax ID number for her but I don't know how to do and what documents I have... Please help me. Thanks a lot.

It is probably most advantageous for you to file jointly with your wife, filing Form 1040 with Form 1116 to claim the Foreign Tax Credit.  Form 1116 is required because you must claim ALL world-wide income earned in 2012 (in this case, your wife's Vietnamese salary), and request a credit for the taxes paid to Vietnam.

You will need to apply for Individual Tax Identification Number (ITIN) for your wife by submitting Form W-7, and that process has undergone some radical procedural changes this past year.  Instead of the simple notarization process, the IRS now requires that your wife's home country certify the photocopy of your passport as a true copy.  This is due to rampant fraud in the ITIN submission process.  The notaries simply cannot tell the difference between a fake passport and the genuine passport.

Your wife needs to contact the Vietnam government agency which issues the passport, make an appointment and request both the certification and an apostille (a certificate of authenticity that states the passport itself is authentic, not a counterfeit). Once she has completed this task, you then prepare the tax return and Form W-7, send them to her for signature, then have her return the certified passport photocopy, the apostille, the signed tax return and the signed W-7 to you for signature and final submission to the IRS.

From start to final mailing to the IRS, the entire process will take about 4 weeks, and the IRS will take about six weeks to issue the ITIN and process the return. Time-consuming, yes, but is CAN be done.

If you believe that you will need professional help filing this year, this IS what I do. Please double-click on my name (Atlanta Tax Expert) above to access my profile. You will find my email address in the signature portion of the profile (scroll down to the BOTTOM of the page).