A: An Individual Taxpayer Identification Number (ITIN) is a tax processing number issued by the Internal Revenue Service. The 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).
A Social Security number (SSN) is a unique identifier issued by the Social Security Administration. Nonresidents that are authorized to work are generally eligible to obtain a Social Security Card.