What Is an ITIN? (And How It Differs From an SSN and EIN)
An ITIN — Individual Taxpayer Identification Number — is a nine-digit tax processing number the IRS issues to individuals who must file or be reported on a U.S. tax return but are not eligible for a Social Security number. For non-U.S. founders with a U.S. LLC, it is the number that most often comes up, and it is also the one most often confused with an EIN.
ITIN vs. SSN vs. EIN
An SSN identifies an individual who is a U.S. citizen or work-authorized resident. An EIN identifies a business entity — it is what your LLC uses to open a bank account, hire employees, and file entity returns, and any non-U.S. person can obtain one for their U.S. LLC without needing an SSN or ITIN.
An ITIN identifies an individual who needs a U.S. tax number but cannot get an SSN. All three are nine digits, which is exactly why people mix them up. The distinction that matters: EIN is for the company, ITIN is for the person.
An ITIN is strictly a tax processing number. It does not authorize you to work in the United States, does not confer immigration status, and does not make you eligible for Social Security benefits.
When a non-U.S. LLC owner actually needs one
You generally need an ITIN when you have a personal U.S. tax filing obligation — most often when you must file Form 1040-NR because your LLC generated income effectively connected with a U.S. trade or business, or when you are a partner in a multi-member LLC receiving a Schedule K-1.
Other triggers include claiming a treaty benefit that requires a taxpayer identification number, being claimed as a dependent or spouse on a U.S. return, and certain withholding or reporting situations.
You often do not need one. Many non-U.S. founders operating a foreign-owned single-member LLC with no U.S.-source effectively connected income have no personal filing obligation, and therefore no ITIN requirement — the LLC files Form 5472 with its own EIN. Whether your income is effectively connected is a genuinely technical question worth asking a cross-border tax professional.
How to apply
You apply on Form W-7, and in most cases it must be submitted together with the tax return that creates the need for it — the IRS generally will not issue an ITIN on request without an attached filing obligation.
You must also prove identity and foreign status. The gold standard is an original passport or a copy certified by the issuing agency, and the IRS is strict here. Rather than mailing your original passport overseas, most applicants use a Certifying Acceptance Agent (CAA), who can verify the document and return it to you, or apply in person at an IRS Taxpayer Assistance Center.
Processing commonly takes around seven weeks and can stretch longer during peak filing season and for applications from abroad. Plan well ahead of any deadline that depends on it.
Keeping it alive
ITINs expire if they are not used on a federal tax return for three consecutive years. The IRS has also periodically expired ITINs by issuance range, so an unused number can lapse without any notice reaching you overseas.
Renewing means submitting Form W-7 again with the supporting documentation, so if you expect an ongoing U.S. filing obligation, it is easier to keep the ITIN in use than to renew it later under deadline pressure.
Key takeaways
- An ITIN is a tax processing number for individuals who must deal with U.S. taxes but cannot get an SSN.
- EIN is for your business; ITIN is for you personally — they are not interchangeable.
- An ITIN grants no work authorization, immigration status, or Social Security eligibility.
- Apply on Form W-7, usually attached to the tax return that creates the need, with certified proof of identity.
- ITINs expire after three consecutive years of non-use and must be renewed.
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