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 Decision 9363: non-US representative of a foreign corporation who needs an ITIN to meet an e-filing requirement | Form W-7 marked "Exception 5, T.D. 9363" and the supporting documents listed in the W-7 Exceptions Tables |
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: allow 7 weeks, or 9 to 11 weeks if submitted during peak processing periods (January 15 through April 30) or from overseas.
The IRS does not provide online tracking for ITIN applications. You can call the IRS (800-829-1040 from the US, 267-941-1000 from outside the US, not toll-free) after the processing period (7 weeks, or 9 to 11 weeks during peak periods or when filing from overseas) 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 (Application type: renewal) with current identity documents and the US federal tax return on which the ITIN will be listed, unless you meet one of the Exceptions 1-5. An ITIN needs to be renewed only if it has expired and will be included on a federal tax return; an ITIN used only on third-party information returns does not need to be renewed yet.
If an expired ITIN is used on a tax return without renewal, processing of the return may be delayed. Submit the renewal Form W-7 together with the return rather than filing the return first.
The 2017 TCJA changes affected the value of dependent ITINs. Through 2017, a $4,050 personal exemption per dependent was available - so an ITIN for a non-citizen dependent saved real tax dollars. For tax years beginning after 2017, the exemption amount is zero (made permanent by P.L. 119-21). The nonrefundable Credit for Other Dependents ($500) can 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 a nonresident alien claiming a tax treaty benefit, (b) for a nonresident alien filing a US tax return, (c) for a resident alien (by days present) filing a return, (d) through (g) for dependents, spouses, and students, professors, and researchers, and (h) for other reasons, including the Exception 1-5 situations. 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. Processing of the return may be delayed. Submit the renewal Form W-7 with the return.
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: Check whether your ITIN has expired (not included on a federal return for 3 consecutive tax years, or assigned before 2013 and never renewed) and attach the renewal Form W-7 to the return on which it will be used.