How to Apply for an ITIN: Form W-7, Timing and Common Mistakes
In this guide
- What is an ITIN, and what is it not?
- Who needs an ITIN?
- Who should not apply?
- How do you apply, step by step?
- When should you apply?
- What if the deadline arrives before your ITIN does?
- How long does an ITIN take?
- What if your ITIN expired?
- What if you later get an SSN?
- Common mistakes to avoid
- Frequently asked questions
- Key takeaways
- Related guides
- Sources
Quick answer: How to apply for an ITIN comes down to one form and one rule. You complete Form W-7, attach your federal tax return, and send both to the IRS together, on or before the return’s due date. An ITIN is only for people who have a federal tax purpose and are not eligible for a Social Security number. The IRS says to allow 7 weeks for a status notice.
Most newcomers hit the ITIN question the same way: a bank, an employer or a tax form asks for a nine-digit number, and you do not have an SSN. This guide walks through who qualifies, how the application package works and what to do if the tax deadline arrives before the number does. Everything below comes from the IRS ITIN page, last updated by the IRS on 28 October 2025. If you are still deciding between the two numbers, read SSN vs ITIN first.
What is an ITIN, and what is it not?
An Individual Taxpayer Identification Number is a nine-digit number the IRS issues for federal tax purposes only. It is useful for filing, but it does a lot less than people hope.
| An ITIN does | An ITIN does not |
|---|---|
| Identify you on a federal tax return | Qualify you for Social Security benefits |
| Let you claim certain tax benefits you are otherwise entitled to | Qualify you for the Earned Income Tax Credit |
| Work for resident aliens, nonresident aliens and their spouses or dependents, whatever their immigration status | Change your immigration status or authorise you to work in the US |
Who needs an ITIN?
You need one if you have a federal tax purpose and are not eligible for an SSN. The IRS lists these tax purposes:
- You are legally required to file a federal income tax return.
- You are filing a return to claim a refund, claim a tax benefit or report income.
- You are being claimed as a spouse or dependent for a tax benefit.
- You need a taxpayer ID for another federal tax purpose.
Spouses and dependents qualify only if they can be claimed for a tax benefit or file their own return. A return with all zero entries generally shows no federal tax purpose, so no ITIN or return is needed in that case.
Who should not apply?
US citizens, green card holders and anyone eligible for an SSN do not need an ITIN. That includes nonresident aliens who hold a US work visa, because they qualify for an SSN. If you later receive an SSN you cannot keep both; see the section on that below.
How do you apply, step by step?
- Confirm you have a federal tax purpose and are not eligible for an SSN.
- Complete Form W-7, the Application for IRS Individual Taxpayer Identification Number. The IRS page links to the form and its instructions (12/2024 revision).
- Prepare your federal tax return. The IRS says to include the return in the application package and not to file it separately.
- Gather the supporting documents. The IRS ITIN page points to a separate supporting-documents page and does not list them, so read that page before you send anything. Mailing original documents is one reason to allow extra time: the IRS says to contact it if originals are not returned within 60 days.
- Apply by mail or in person using the IRS “How to apply for an ITIN” page.
This site does not list the accepted documents or the agents who can certify copies, because we could not confirm them against the IRS pages. Use the IRS supporting-documents page as the source.
When should you apply?
Apply on or before your tax return’s due date. You can apply at any time if you are filing a prior-year return or you meet an exception to the filing requirement. If you want to claim certain credits, the ITIN must be assigned to you, to your spouse if you file jointly, and to your dependent by the return due date, including extensions. The assignment date is generally the date the IRS receives your complete package.
What if the deadline arrives before your ITIN does?
The IRS gives two routes that do not involve a W-7:
- Extension: file Form 4868 by the April due date, which gives you until October 15. Write “ITIN TO BE REQUESTED” in the SSN/ITIN field. Any tax you owe is still due by the April date.
- Estimated payments: use Form 1040-ES or 1040-ES (NR), write “ITIN TO BE REQUESTED” in the voucher field, and do not include a W-7.
How long does an ITIN take?
| Situation | What the IRS says |
|---|---|
| Normal | Allow 7 weeks for notice of your application status |
| Peak season (15 January to 30 April) or applying from overseas | 9 to 11 weeks |
| No notice after that time | Contact the IRS |
What if your ITIN expired?
The IRS says to renew an ITIN if it has expired and you need to file a US income tax return. The ITIN page does not give expiry dates or other renewal rules, so follow the IRS “How to renew an ITIN” page for those.
What if you later get an SSN?
You cannot have both. Stop using the ITIN and write to the IRS with your name, address, ITIN, a copy of your CP565 notice if you have it, and a copy of your Social Security card. The IRS then voids the ITIN and links your earlier records to the SSN. Send it to the address on the IRS page.
Common mistakes to avoid
- Filing the tax return separately instead of inside the W-7 package.
- Applying when you are eligible for an SSN, for example on a work visa.
- Missing the April payment date because you were waiting for the ITIN. An extension moves the filing date, not the payment date.
- Assuming an ITIN gives you work authorisation or Social Security benefits. It does neither.
- Using the ITIN and an SSN at the same time.
Frequently asked questions
Can I apply for an ITIN if I am not in the US?
The IRS says applications from overseas can take 9 to 11 weeks, which shows they are accepted. It does not set out other rules for people abroad on the ITIN page, so check the W-7 instructions.
Do I need a tax return to get an ITIN?
Generally yes: the IRS says to include your federal tax return in the package. The ITIN page does not describe the exceptions, so see the W-7 instructions if you think one applies.
Who do I call if my application is stuck?
The IRS lists 800-829-1040 in the US and 267-941-1000 from abroad (not toll-free).
Key takeaways
- Apply with Form W-7 plus your federal tax return, in one package, by the return due date.
- An ITIN is for federal tax purposes only and is not for anyone eligible for an SSN.
- If the due date arrives first, use an extension and write “ITIN TO BE REQUESTED”. Tax is still due in April.
- Allow 7 weeks, or 9 to 11 in peak season or from overseas.
Related guides
- SSN vs ITIN: which one do you need as a new immigrant?
- Tax benefits you can claim with an ITIN
- The substantial presence test
- Nonresident alien tax guide
- Your first 90 days in a new country
This page is general information, not legal or tax advice. Last updated: October 2026.
Sources
Internal Revenue Service: Individual Taxpayer Identification Number (ITIN) page.