Glossary/Filings & Documents/Individual Taxpayer Identification Number
Filings & Documents

Individual Taxpayer Identification Number

ITIN

Individual Taxpayer Identification Number is a nine-digit IRS tax processing number issued to individuals who must file US taxes but are not eligible for a Social Security Number, including many non-resident foreign founders.

What ITIN is

The Individual Taxpayer Identification Number (ITIN) is a tax-only identification number issued by the US Internal Revenue Service to individuals who have a US tax filing or reporting obligation but do not qualify for a Social Security Number (SSN). It is formatted identically to an SSN as XXX-XX-XXXX but always begins with the digit 9.

The ITIN does not authorize work in the US, does not provide eligibility for Social Security benefits, and does not establish immigration status; it exists solely so the IRS can process returns, withhold tax correctly, and apply tax-treaty benefits for non-resident persons.

Founders of foreign-owned US LLCs typically need an ITIN if they are individually liable for filing Form 1040-NR, claiming a tax-treaty rate on Form W-8BEN, or being listed as a beneficial owner on filings that require a US TIN.

ITINs are obtained by filing IRS Form W-7 alongside a federal tax return, with original or certified-copy passport documentation, either through a Certified Acceptance Agent (CAA) or directly to the IRS Austin processing center. Since 2016, ITINs that are unused for three consecutive tax years expire automatically and must be renewed.

When you will meet ITIN

A foreign founder typically needs an ITIN when filing personal Form 1040-NR for US-source income, claiming a reduced withholding rate under a tax treaty, applying for an EIN online (the responsible party path requires SSN or ITIN), or being named as a partner on a US partnership return.

Many founders of foreign-owned single-member LLCs do not need an ITIN because the LLC itself files Form 5472 + pro-forma 1120 using its EIN, but founders who add a US-source revenue stream or become a partner in a US LLC will hit the ITIN requirement.

Where this comes up in our guides

Individual Taxpayer Identification Number FAQ

ITIN applications filed with a complete tax return through a Certified Acceptance Agent typically take 7 to 11 weeks. Direct mail applications to the IRS Austin processing center can take longer during peak filing season (January to April). The IRS will not issue an ITIN unless a tax return or treaty-claim form is attached unless an exception applies.
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Filings & Documents
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ITIN
Confirm current figures with the official registry or a qualified adviser before relying on them.
Related terms
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Sources
  1. 1IRS - Individual Taxpayer Identification Number
  2. 2IRS Form W-7
  3. 3IRS - Certified Acceptance Agent Program
Definition reviewed March 2026.
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