An Individual Taxpayer Identification Number (ITIN) is the IRS's substitute for a Social Security Number for foreign individuals who have a US tax filing or reporting obligation but aren't eligible for an SSN. Foreign sellers of US real estate need one. Foreign partners in US partnerships need one. Foreign students claiming treaty benefits need one. Spouses and dependents of US persons being claimed on a return need one. The application process - Form W-7 - is more complicated than people expect because the IRS will not accept photocopied passports, and lost original passports are a real problem. There are three viable application channels and choosing the right one for the situation matters.
Foreign individuals who need a US taxpayer identifying number but can't get an SSN apply for an ITIN by filing Form W-7 - typically attached to a tax return that creates the filing obligation, but in five specific exception cases, with documentation supporting the exception instead. The cleanest route for most non-resident applicants is through a Certifying Acceptance Agent (CAA) like tk.cpa, who can verify original identity documents in person and submit certified copies, eliminating the need to mail your original passport to the IRS.
If you're a foreign individual and any of these apply, you need an ITIN:
Who does NOT need an ITIN:
The standard ITIN application path is to file Form W-7 together with the tax return that creates the filing obligation. The W-7, the tax return, and the supporting identity documents are mailed (or hand-delivered) as a package to the IRS Austin Service Center.
The IRS processes the W-7 first, assigns the ITIN, writes it on the tax return, then processes the tax return. So a Form 1040-NR from a foreign person without an ITIN doesn't get rejected for missing TIN - it gets held until the W-7 issues a number.
For five specific situations, you can apply for an ITIN without attaching a tax return - just Form W-7 plus exception-specific supporting documents.
| Exception | When It Applies | What to Attach |
|---|---|---|
| Exception 1 | Passive income from a US partnership or third-party withholding situation requiring the W-8BEN to have a TIN | Letter from withholding agent / partnership stating the income flow requiring TIN |
| Exception 2 | Wages, scholarship, or treaty-based exemption requiring TIN on Form 8233 or W-8BEN | Letter from employer/institution; treaty article reference |
| Exception 3 | Third-party reporting of mortgage interest (Form 1098) | Mortgage documents from US lender |
| Exception 4 | Disposition by foreign person of US real property interest (FIRPTA) | Form 8288, 8288-A, or 8288-B; sale documents |
| Exception 5 | Treasury regulations require TIN reporting (e.g., obligations to file Form 8939 or similar) | Specific regulatory citation and supporting documents |
Exception 4 (FIRPTA) is the most commonly used exception in cross-border practice. A foreign seller of US real estate needs an ITIN to file Form 8288-B for a withholding certificate before closing - well before the eventual tax return is due. Exception 4 lets them apply for the ITIN concurrently with the 8288-B filing rather than waiting until the 1040-NR is due the following year.
| Channel | How It Works | Key Trade-Off |
|---|---|---|
| Direct mail | Mail Form W-7 plus original passport (or certified copies from issuing agency) to IRS Austin | You ship your real passport. Lost mail = lost passport. Processing 7-11 weeks. No travel possible during this time. |
| Certifying Acceptance Agent (CAA) | CAA verifies your original passport in person, certifies the copy, then submits W-7 with the certified copy. Original passport stays with you. | Best route for most applicants. Some CAAs charge $200-$500. tk.cpa is a CAA. |
| IRS Taxpayer Assistance Center (TAC) | Walk in to a designated TAC with original documents. They verify in person and submit on your behalf. | Free, but requires US travel and an appointment. Limited TAC locations offer this service. |
The mailed-passport route is risky in practice. The IRS holds passports for 7-11 weeks during processing, sometimes longer if there's a question. A foreign individual who needs to travel during that period can't. Lost passport reports during the application window are not uncommon.
A Certifying Acceptance Agent can verify original documents and submit certified copies without the applicant ever surrendering the passport. This is what the IRS authorized CAAs to do specifically to address the lost-passport problem. The CAA verifies the original document in person (in office or via video call with appropriate verification protocols), produces a Certificate of Accuracy (Form W-7 COA), and submits the certified copy with the W-7.
The IRS accepts 13 categories of identity documents, but a passport is the only single document that proves both identity and foreign status. With a passport, you need only one document. Without a passport, you need two documents - one to prove identity, another to prove foreign status (with at least one having a photo).
If you don't have a passport, the most common combinations:
Documents must be either originals or certified copies issued by the original issuing agency (not by a notary or third party). Photocopies, even notarized photocopies, are rejected.
Standard processing: 7-11 weeks for mailed applications, slightly faster for in-person submissions. Peak filing season (January-April) is slower. Renewal applications are faster than initial applications.
The IRS does not provide online tracking for ITIN applications. You can call the ITIN telephone help line (1-800-908-9982 from the US, +1-267-941-1000 internationally) about 7 weeks after submission to check status.
If approved, you receive a CP 565 notice with your assigned ITIN. If rejected, you receive a CP 567 explaining what to fix. Common rejection reasons:
ITINs expire if not used on a federal tax return for 3 consecutive tax years. The IRS publishes annual lists of ITINs scheduled to expire, organized by middle-digits.
To renew, file Form W-7 marked "Renewal" with current identity documents. Tax return is not required for renewal applications. The renewal can be filed with the next tax return that uses the ITIN, or in advance.
If an ITIN has expired and is used on a tax return, the IRS holds the return and notifies the filer. The eventual return processing is delayed by the renewal cycle - which can affect refunds. Best practice: renew an expired ITIN before filing the return.
The 2017 TCJA changes affected the value of dependent ITINs. Through 2017, a $4,000 personal exemption per dependent was available - so an ITIN for a non-citizen dependent saved real tax dollars. From 2018-2025, exemptions are zero. Some refundable credits (Other Dependent Credit, $500) still require an ITIN for the dependent.
For a non-resident alien spouse of a US person electing under §6013(g) or §6013(h) to be treated as a US resident, the spouse needs an ITIN to be on the joint return. The §6013 election statement and the W-7 are filed together with the joint 1040.
The executor or trustee needs to obtain an ITIN if they don't have one and they're filing US tax returns on behalf of the estate or trust. The ITIN goes on the fiduciary return (Form 1041 or 1040-NR for the estate).
A foreign individual receiving a Schedule K-1 from a US partnership needs an ITIN to file the consequent 1040-NR. The partnership reports the K-1 with TIN unspecified initially; the foreign partner applies for an ITIN concurrently with their first 1040-NR filing. Subsequent year K-1s show the ITIN.
Foreign sellers of US real estate often need the ITIN urgently for the Form 8288-B withholding certificate filing - which has to happen before closing. Standard processing of 7-11 weeks may not fit the closing schedule. Working with a CAA who can submit Exception 4 applications, expedited where possible, is critical for time-sensitive deals.
Notarized photocopies of passports. A notary's certification is not what the IRS wants. The certification must come from the issuing agency (the passport-issuing government) or from a CAA verifying the original.
Wrong reason code on Form W-7. The W-7 has a series of "Reason for application" boxes. Box (a) for nonresident filing a US tax return, (b) for a US resident, (c) through (h) for various dependent and exception scenarios. Wrong box selection can trigger rejection.
Missing the supporting tax return or exception documentation. A standalone W-7 with no return and no exception documentation is rejected.
Treating the ITIN as a work authorization or government ID. An ITIN is for tax purposes only. It does not authorize work in the US, does not entitle the holder to Social Security, and is not a substitute for any immigration document.
Using an expired ITIN on a return. The IRS will hold the return until renewal is processed. Better to renew first.
If you're a foreign individual planning a US transaction (real estate sale, US partnership investment, US business setup): Get the ITIN moving early. The 7-11 week timeline can blow up closings or filing deadlines.
If you have a passport: Use it. Single-document submission is much cleaner than the multi-document combinations.
If your application is time-sensitive: Use a CAA who can process Exception 4 (FIRPTA), Exception 2 (treaty), or other applicable exception in parallel with your transaction. tk.cpa handles these regularly.
If you're a US person with a foreign spouse: Apply for the spousal ITIN concurrently with your first joint return after the §6013 election. The W-7 plus tax return package goes to Austin together.
For renewals: Watch the IRS annual expiration notices. Renew before filing season if possible. The renewal application is faster than initial.