An Individual Taxpayer Identification Number or ITIN is a nine-digit number assigned by the US Internal Revenue Service (IRS) to individuals who are required for US tax purposes to have a US taxpayer identification number but who do not have or are not eligible to get a Social Security Number (SSN). An ITIN is used primarily by nonresident aliens for tax purposes .

The ITIN is for federal tax purposes only. An ITIN does not entitle the individual to Social Security Benefits and does not change the immigration status or the right to work in the US of the individual.

An ITIN is for US IRS tax identification purposes only and is not valid for identification purposes outside of the US tax system.

An ITIN expires 5 years after the date of issuance. IRS Form W-7 is used to apply for an An ITIN. Proof of foreign status must be submitted with IRS Form W-7. An original passport or a certified copy from the issuing agency are the most common means of proving valid foreign status.