Form W-7 applies for an ITIN — an Individual Taxpayer Identification Number for people who must file U.S. taxes but can't get a Social Security number. Two things decide whether it's approved: the reason code (boxes a–h) that explains why you need an ITIN, and the identity documents, which must be originals or certified copies. A passport is the one document that stands alone.
What Form W-7 Is
Form W-7, "Application for IRS Individual Taxpayer Identification Number," gives a taxpayer ID to people the SSN system doesn't cover: nonresident and resident aliens with a U.S. filing requirement, and the spouses or dependents of U.S. citizens and residents. An ITIN is for tax purposes only — it doesn't grant work authorization or immigration status, it just lets the IRS process your return.
The Reason Code Is the First Decision
Boxes a through h at the top ask why you're applying. This drives which documents and attachments you need:
- (a) Nonresident alien required to get an ITIN to claim a tax treaty benefit
- (b) Nonresident alien filing a U.S. tax return
- (c) U.S. resident alien filing a U.S. tax return
- (d) Dependent of a U.S. citizen or resident alien
- (e) Spouse of a U.S. citizen or resident alien
- (f)–(h) Nonresident students, professors, or other specific categories
Choosing a code that doesn't match your situation — or checking more than one — is the most common W-7 rejection.
How to Fill Form W-7
- Reason for applying. Check the single box that fits, and add the treaty country and article number if you selected (a).
- Name and mailing address. Your legal name and the address where the IRS should send your ITIN.
- Birth information and foreign status. Date and country of birth, and your country of citizenship.
- Identity documents. A valid passport proves both identity and foreign status on its own; without one, you supply a combination (e.g. national ID plus visa). Documents must be originals or certified by the issuing agency.
- Sign, and attach your tax return. Most W-7s are filed with the federal tax return that creates the ITIN need, mailed together to the ITIN unit.
What's the difference between an ITIN and an SSN?
An SSN (applied for on Form SS-5) is for people authorized to work in the U.S. and is issued by the Social Security Administration. An ITIN is issued by the IRS purely so people who aren't eligible for an SSN can still meet a tax obligation. You never hold both at once for the same purpose — if you become eligible for an SSN, you stop using the ITIN.
Do I also need Form W-8BEN?
Sometimes. If you're a foreign individual receiving certain U.S.-source income, the payer may ask for Form W-8BEN to certify your foreign status and treaty eligibility, separate from the W-7 that gets your ITIN. The two often travel together for nonresidents, and both reuse the same identity and foreign-status details.