ITIN Requirements 2026: Eligibility and Documents Needed

Who Is Eligible for an ITIN?

The IRS issues ITINs to individuals who have a US tax filing obligation or a tax-related need but are not eligible for a Social Security Number. You must meet two basic criteria: you need a valid tax reason, and you must be ineligible for an SSN.

The following groups typically qualify for an ITIN:

• Non-resident aliens required to file a US federal tax return
• Resident aliens (based on the substantial presence test) who are not eligible for an SSN
• Spouses of US citizens or residents being claimed on a joint tax return or as an exemption
• Dependents of US citizens or residents listed on a federal tax return
• Non-resident aliens claiming a tax treaty benefit
• Non-resident alien students, professors, or researchers filing a US tax return or claiming an exemption
• Foreign nationals with US-source income subject to third-party reporting or withholding

If you are eligible for a Social Security Number, the IRS will reject your ITIN application. Apply for an SSN first. If the Social Security Administration denies your SSN application, include their denial letter with your Form W-7 submission.

Valid Reasons for Needing an ITIN

The IRS requires you to select a reason for applying on Form W-7. Your reason must fall into one of these categories:

ITIN Document Requirements

Every ITIN application must include documents that prove two things: your identity (who you are) and your foreign status (that you are not a US citizen). A valid passport is the only single document that proves both. If you do not have a passport, you need at least two documents from the IRS-approved list below.

For the complete document checklist with detailed guidance on each option, see our complete document checklist.

All 13 Documents the IRS Accepts

The IRS accepts the following 13 document types for ITIN applications. Each document must be an original or a certified copy from the issuing agency. Regular photocopies are not accepted.

Form W-7: The ITIN Application Form

IRS Form W-7, titled “Application for IRS Individual Taxpayer Identification Number,” is the official form you must complete to apply for an ITIN. The form collects your personal information, your reason for applying, and details about the tax return you are attaching.

Key sections of Form W-7 include:

• Reason for applying (Line 1a through 1h). You must check exactly one box that matches your situation. Common selections include filing a tax return (1a), claiming a tax treaty benefit (1b), and spouse or dependent of a US citizen (1e or 1d).
• Name and birth information (Lines 1 through 4). Your name must match exactly what appears on your identity documents. Include any prior names or aliases.
• Foreign and US address (Lines 5 and 6). Provide both your foreign address and a US mailing address where you want the IRS to send your CP565 notice.
• Country of citizenship and entry information (Lines 7 and 8). If you have entered the US, provide your entry date and immigration status.
• Signature. The form must be signed and dated. For dependents under 18, a parent or guardian signs.

Errors on Form W-7 are the most common reason the IRS rejects ITIN applications. For step-by-step instructions, see our guide to completing Form W-7.

What Happens If Your Documents Are Incomplete

If the IRS finds your application incomplete or your documents insufficient, they will not simply reject and discard your submission. Instead, they send a written notice to the address on your Form W-7 explaining exactly what is missing or incorrect.

Common issues that trigger a notice include:

• Missing signature on Form W-7
• Documents that do not match the name on the application
• Expired identity documents
• No tax return attached when one is required
• Checking the wrong reason-for-applying box
• Submitting regular photocopies instead of certified copies or originals

Each correction cycle adds 4 to 8 weeks to your total processing time. The best way to avoid this is to have your application reviewed by a professional before submitting. Our team at itin.so reviews every application for completeness and accuracy before it reaches the IRS.

Using a CAA to Simplify the Process

A Certifying Acceptance Agent (CAA) is an individual or organization authorized by the IRS to assist with ITIN applications. Working with a CAA offers three major advantages:

1. Keep your original documents. A CAA verifies your identity and foreign-status documents in person or via a secure process. The CAA sends a Certificate of Accuracy to the IRS instead of your original documents. You never risk losing your passport in the mail.
2. Fewer errors and rejections. CAAs are trained on IRS requirements and review your Form W-7 for accuracy before submission. This dramatically reduces the chance of a rejection or correction notice.
3. Expert guidance on document selection. If you are unsure which documents to use or how to obtain certified copies, a CAA walks you through the process and tells you exactly what you need.

At itin.so, our CAA team handles everything from document verification to Form W-7 preparation and submission. Learn more about the full process in our guide on how to get an ITIN number.