What an ITIN is and who needs one
ITIN basics: what it is and how to apply. Lesson 1, 12 min.
An Individual Taxpayer Identification Number (ITIN) is a 9-digit number. The IRS issues it to people who need a US taxpayer identification number for federal tax purposes and who are not eligible for a Social Security number (SSN).
Who needs an ITIN
The IRS says you need an ITIN if you have a federal tax purpose and you are not eligible for an SSN. Resident aliens, nonresident aliens, and their spouses and dependents can apply regardless of immigration status. Form W-7 lists these reasons to apply:
- A nonresident alien who must get an ITIN to claim a tax treaty benefit.
- A nonresident alien who files a US federal tax return.
- A US resident alien, based on days present in the US, who files a US federal tax return.
- A dependent of a US citizen or resident alien.
- A spouse of a US citizen or resident alien.
- A nonresident alien student, professor or researcher who files a US federal tax return or claims an exception.
- A dependent or spouse of a nonresident alien who holds a US visa.
- Other reasons, which the instructions describe.
Who does not need one
US citizens, green card holders and anyone who is eligible for an SSN do not need an ITIN. The Form W-7 instructions say: do not complete Form W-7 if you have an SSN or if you are eligible to get one. If you have an SSN application pending, do not file Form W-7.
What an ITIN does not do
The IRS issues an ITIN for federal tax purposes only. The IRS says an ITIN does not:
- Qualify you for Social Security benefits or the Earned Income Tax Credit.
- Provide or change immigration status.
- Authorize you to work legally in the US.
- Serve as identification outside the federal tax system.
If you later get an SSN
You cannot have both an ITIN and an SSN. When you get an SSN, stop using the ITIN and use the SSN for tax purposes. Tell the IRS by letter or at a local IRS office, so that it combines your tax records under the SSN. If you do not, you may not get credit for all wages paid and taxes withheld.
Sources
IRS pages checked on 2026-11-04.
- IRS, Individual taxpayer identification number (ITIN): https://www.irs.gov/individuals/individual-taxpayer-identification-number
- IRS, Instructions for Form W-7 (December 2024 revision): https://www.irs.gov/instructions/iw7
