Individual Taxpayer Identification Number (ITIN) business definition

A tax-processing number issued by the Internal Revenue Service to individuals who are required to have a U.S. taxpayer identification number but are not eligible to obtain a Social Security number. ITINs are issued regardless of immigration status because both resident and nonresident aliens may have U.S. tax return responsibilities. Each ITIN is a nine-digit number that begins with 9 and includes either a 7 or 8 as the fourth digit.