A TIN is defined as the identifying number assigned to a person or entity under Internal Revenue Code, Section 6109. A TIN may be a SSN, EIN, ITIN or ATIN. A TIN can have only nine (9) numbers. It cannot have more or less than nine numbers nor can it have letters.
- An SSN is a Social Security Number issued by the Social Security Administration.
- An EIN is an Employer Identification Number (EIN) issued by the IRS.
- An ITIN is an Individual Taxpayer Identification Number issued by the IRS. Resident aliens and nonresident aliens, who are not eligible for SSNs, use ITINS. An ITIN is an individual Taxpayer Identification Number (ITIN) issued by the IRS and may be used as a TIN to meet federal tax obligations only. An ITIN has nine numbers in the same format as an SSN and always begins with the number 9. The fourth and fifth digits are always within the range of 70 through 88.
- An ATIN is an Adoptive Taxpayer Identification Number issued by the IRS. An ATIN is only a temporary taxpayer identification number issued for a child born, and adopted, in the United States. An ATIN should be requested when an SSN cannot be obtained in time to file your tax return. Once the adoptive parent obtains an SSN for the adoptive child, the ATIN becomes obsolete. An ATIN contains nine numbers in the same format as an SSN.
For additional information see Publication 1281, Online TIN Matching Program.