Individual Taxpayer Identification Numbers (ITIN) are assigned by the Internal Revenue Service (IRS), not the Social Security Administration. They are assigned to certain nonresident and resident aliens, their spouses, and dependents. The ITIN is only available to individuals who cannot get a Social Security Number (SSN). It is a 9-digit number, beginning with the number "9," formatted like an SSN (NNN-NN-NNNN). It may be used for Federal tax purposes only. It cannot be used to work.

If you are a non-citizen and have applied for a SSN, but are not eligible, you will receive a letter from Social Security that explains why you are not eligible for a number. If you have a need for a Tax Identification Number, you will need to file form W-7 with the IRS to obtain an ITIN.