What is an ITIN?
Individual Taxpayer Identification Number
Short answer
An ITIN is a nine-digit tax processing number the IRS issues to people who must file or be listed on a US return but are not eligible for a Social Security number.
What it is
An ITIN (Individual Taxpayer Identification Number) always begins with a 9 and is used only for federal tax purposes. It does not authorize work, change immigration status or qualify the holder for Social Security benefits. Applicants file Form W-7, usually with a tax return, and prove identity and foreign status with original documents or certified copies.
An ITIN that has not been used on a federal return for three consecutive years expires and must be renewed before the next return is filed, or credits and processing are delayed.
Why it matters for a tax firm
Firms serving immigrant communities handle ITIN applications and renewals every season. The paperwork is document-heavy and in many cases bilingual, which is why Certifying Acceptance Agents exist.
How XyloDocs handles it
XyloDocs was built inside a bilingual practice that is also a Certifying Acceptance Agent. Clients send identity documents and tax forms over WhatsApp or text, in Spanish or English, and the firm sees what is still missing.
Related terms
Read more on XyloDocs
Sources
Questions about ITIN
Does an ITIN expire?
Yes, if it is not used on a federal tax return for three consecutive years. Renew with Form W-7 before filing.
Can someone with an ITIN claim the child tax credit?
The child must have a Social Security number valid for employment. An ITIN parent may still claim the credit for an SSN child; an ITIN child may qualify for the credit for other dependents.
Last reviewed: October 16, 2026. This glossary explains terms; it is not legal or tax advice. Check the cited source for the current rule.
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