저도 오래되서 가물가물 한데 처음 신고할때 아내의 택스아이디랑 같이 신청했어요. (W-7폼 작성)
1040, W-7, 그리고 여권 사본 공증 한 서류를 첨부하여 ITIN 신청하시는 곳으로 보내시면 됩니다. 싸인 꼭 하시구요. 여권은 사본인지 원본인지 확인해 보셔야할 듯…

아랫글 참조하세요~

http://www.stepbystepselfpublishing.net/how-to-get-an-itin.html

1. You must download a blank Form W-7 from the IRS website. The form is available in English and Spanish. Print a few copies, so you can practice.

2. Fill it out– do not miss any of the lines or it will be returned.

3. You must sign the W-7 form with an original signature (wet signature, NO photocopies), and send a valid identification. Here’s a link to a blank Form W-7 for you to download and use. The sample one is below, and you can’t use that, because it is already filled in (by me) so you can use it as a guide.

4. Make sure you have valid identification. Unless you are a minor child, you must supply an ID with a clear photograph. A passport is best. But you can also use something like a Driver’s license and a birth certificate (together), as long as the driver’s license has a photo. You basically need to give them your passport, or a notarized (very clear, preferably in color) copy of your passport.

5. If you send in an Form W-7 application, using just a photocopied document is not sufficient. Your identifying documents must be certified/notarized if you send a photocopy.

You must send EITHER:
An original ID (which will be returned). (I got my in-law’s ITINs using a voter registration card and a birth certificate for both of them, but I sent in original documents (which were returned to me).
OR
If you don’t send original documents (such as an original passport or driver’s license), then you must send a notarized copy. (*Note: Notarized passport copies must have an ‘Apostille’ attached). Copies will NOT be returned, regardless of the situation. So you might want to make more than one. Originals, on the other hand, will be returned.