Answer:
Form W-7 is Application for IRS Individual Taxpayer Identification Number. An individual taxpayer identification number (ITIN) is issued by the IRS. It's for federal tax purposes only.
The IRS assigns ITINs to individuals who are required to have a U.S. taxpayer identification number but who aren't eligible for a social security number.
For more information, go to www.irs.gov/taxtopics for Topic 857: Individual Taxpayer Identification Number (ITIN) Form W-7. Also go to www.irs.gov/formspubs for Publication 1915: Understanding Your IRS Individual Taxpayer Identification Number.