That is a good question. I had read that the first 3 #s of a foreign student SS# differ from domestic SS#s. I tried to look it up, and this is the best I cd find:P
What is an ITIN?
An Individual Taxpayer Identification Number (ITIN) is a tax processing number issued by the Internal Revenue Service. It is a nine-digit number that always begins with the number 9 and has a range of 70-88 in the fourth and fifth digit. Effective April 12, 2011, the range was extended to include 900-70-0000 through 999-88-9999, 900-90-0000 through 999-92-9999 and 900-94-0000 through 999-99-9999. IRS issues ITINs to individuals who are required to have a U.S. taxpayer identification number but who do not have, and are not eligible to obtain a Social Security Number (SSN) from the Social Security Administration (SSA).
ITINs are issued regardless of immigration status because both resident and nonresident aliens may have a U.S. filing or reporting requirement under the Internal Revenue Code.
Individuals must have a filing requirement and file a valid federal income tax return to receive an ITIN, unless they meet an exception.
What is an ITIN used for?
ITINs are for federal tax reporting only, and are not intended to serve any other purpose. IRS issues ITINs to help individuals comply with the U.S. tax laws, and to provide a means to efficiently process and account for tax returns and payments for those not eligible for Social Security Numbers (SSNs).
An ITIN does not authorize work in the U.S. or provide eligibility for Social Security benefits or the Earned Income Tax Credit.
Who needs an ITIN?
IRS issues ITINs to foreign nationals and others who have federal tax reporting or filing requirements and do not qualify for SSNs. A non-resident alien individual not eligible for a SSN who is required to file a U.S. tax return only to claim a refund of tax under the provisions of a U.S. tax treaty needs an ITIN.
Other examples of individuals who need ITINs include:
• A nonresident alien required to file a U.S. tax return
• A U.S. resident alien (based on days present in the United States) filing a U.S. tax return
• A dependent or spouse of a U.S. citizen/resident alien
• A dependent or spouse of a nonresident alien visa holder
http://www.irs.gov/Individuals/General-ITIN-Information
What is interesting is that some foreign students are exempt from paying SS and Medicare taxes on their earnings. It would be interesting to look at Obama's tax returns when he received his advance.