If you’re a non-US resident who needs to file a U.S. tax return, open a business, or claim tax treaty benefits, you’ll likely need an Individual Taxpayer Identification Number. Understanding the ITIN application process upfront can save you weeks of delays and prevent the most common rejection reasons.
This guide walks through exactly what an ITIN is, who needs one, what documents you’ll need, and how the application process actually works from start to finish.
What Is an ITIN?
An Individual Taxpayer Identification Number (ITIN) is a nine-digit number issued by the IRS to individuals who need to file a U.S. tax return but aren’t eligible for a Social Security Number. It’s used strictly for federal tax reporting purposes and does not authorize you to work in the United States or change your immigration status.
Who Needs an ITIN?
You may need an ITIN if you’re:
- A non-US resident required to file a U.S. tax return
- A foreign investor with U.S.-source income
- The spouse or dependent of a U.S. citizen or resident, being claimed on a tax return
- A non-US resident who owns or is starting a U.S. business
- Someone claiming a tax treaty benefit between the U.S. and your home country
ITIN vs. SSN: What’s the Difference?
| ITIN | SSN | |
|---|---|---|
| Issued by | IRS | Social Security Administration |
| Purpose | Federal tax filing only | Tax filing, employment eligibility, benefits |
| Who it’s for | Non-US residents, foreign investors, dependents ineligible for an SSN | U.S. citizens and authorized workers |
| Authorizes work in the U.S.? | No | Yes |
Documents Required for the ITIN Application
The IRS requires documentation proving both your identity and your foreign status. Commonly accepted documents include:
- A valid, unexpired passport (accepted as standalone proof of both identity and foreign status)
- National identification card (if it includes a photo, name, current address, and expiration date)
- U.S. or foreign driver’s license
- Foreign voter’s registration card
- Birth certificate (required for dependents under 18 in most cases)
If you don’t use a passport, you’ll typically need to combine two other documents to satisfy both the identity and foreign status requirements.
Step-by-Step: How the ITIN Application Process Works
Step 1: Complete Form W-7
This is the official ITIN application form, requiring your personal information and the reason you need an ITIN.
Step 2: Attach Your Federal Tax Return
In most cases, your ITIN application must be submitted along with the tax return that requires it, unless you qualify for one of the limited exceptions to this rule.
Step 3: Submit Your Identity Documents
You have three options for this step:
- Mail original documents (or certified copies from the issuing agency) directly to the IRS
- Visit an IRS Taxpayer Assistance Center in person
- Work with a Certified Acceptance Agent (CAA), who can verify your documents without requiring you to mail your original passport
Step 4: Wait for Processing
ITIN processing timelines vary, but many applicants receive their number within about seven weeks — sometimes longer during peak tax season.
Step 5: Receive Your ITIN
Once approved, the IRS mails you an official notice with your new ITIN, which you’ll use for all future federal tax filings.
Why Working With a Certified Acceptance Agent Matters
Mailing your original passport to the IRS means being without it for weeks — a real problem if you need it for travel, banking, or identification in the meantime. A Certified Acceptance Agent (CAA) is authorized by the IRS to review and verify your original identity documents in person, so you keep your passport while your application moves forward.
Our team includes IRS-authorized Certified Acceptance Agents who handle ITIN application processing without requiring you to part with your original documents.
Common Reasons ITIN Applications Get Rejected
- Incomplete or incorrectly filled out Form W-7
- Missing or expired identity documents
- Applying without attaching the required tax return (when no exception applies)
- Submitting photocopies that aren’t properly certified when mailing directly to the IRS
Does an ITIN Expire?
Yes. ITINs that haven’t been used on a federal tax return for three consecutive years automatically expire and need to be renewed before they can be used again. Additionally, certain ITINs are subject to scheduled expiration based on IRS rules, regardless of usage.
Frequently Asked Questions
How long does it take to get an ITIN?
Processing times vary, but many applicants receive their ITIN within about seven weeks of submission, longer during tax season.
Do I need to mail my passport to the IRS?
Not if you work with a Certified Acceptance Agent, who can verify your original documents in person and avoid the need to mail them.
Can I apply for an ITIN for my spouse or children?
Yes. Spouses and dependents who aren’t eligible for a Social Security Number but need to be claimed on a U.S. tax return typically need their own ITIN.
What’s the difference between an ITIN and an EIN?
An ITIN identifies an individual for tax filing purposes. An EIN identifies a business. Non-US residents starting a U.S. business often need both — see our guide on how to get an EIN number.
Can I use an ITIN to work legally in the United States?
No. An ITIN is strictly for federal tax reporting and does not authorize employment or change your immigration status.
Do ITINs expire?
Yes, if unused on a tax return for three consecutive years, or if scheduled for expiration under separate IRS rules. Expired ITINs must be renewed before they can be used again.
Ready to Start Your ITIN Application?
Whether you’re applying for the first time or renewing an expired ITIN, working with a Certified Acceptance Agent can make the process faster and keep your original documents in your hands. Schedule a consultation to get started.