An Individual Taxpayer Identification Number (ITIN) is a tax processing number issued by the Internal Revenue Service (IRS) 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). They 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. ITINs do not serve any purpose other than tax reporting.