What is Form W-7?
Application for IRS Individual Taxpayer Identification Number
Short answer
Form W-7 is the application for an ITIN. It is usually filed with a federal tax return and must be supported by original identity documents or certified copies.
What it is
Form W-7 asks why the applicant needs an ITIN, their identity and foreign status, and attaches proof: a passport alone, or a combination of listed documents such as a national ID card, birth certificate or visa. Unless an exception applies, the form is filed together with the tax return it supports.
Applications go by mail to the IRS ITIN Operation, in person at an IRS Taxpayer Assistance Center, or through an Acceptance Agent. A Certifying Acceptance Agent can certify the documents so the applicant keeps the originals.
Why it matters for a tax firm
A W-7 holds up the whole return: the return cannot be processed until the ITIN is assigned. Mistakes in the supporting documents are the usual cause of rejection, so collecting clear copies early matters.
Related terms
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Sources
Questions about Form W-7
Can I file Form W-7 without a tax return?
Only if you meet one of the exceptions listed in the instructions, for example certain third-party reporting or treaty situations. Most applicants attach it to a return.
How long does an ITIN take?
The IRS says about seven weeks, and nine to eleven weeks during peak season or from abroad.
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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