US tax identification numbers confuse almost every international founder at some point. They look similar, but they identify different things and are issued by different agencies.
The three numbers compared
| SSN | ITIN | EIN | |
|---|---|---|---|
| Full name | Social Security Number | Individual Taxpayer Identification Number | Employer Identification Number |
| Identifies | An individual | An individual | A business or other entity |
| Issued by | Social Security Administration | IRS (Form W-7) | IRS (Form SS-4) |
| Who gets it | US citizens and people authorised to work in the US | People who must file or be named on a US tax return but cannot get an SSN | Companies, partnerships, trusts, estates and others |
| Allows work in the US | Yes | No | Not applicable |
| Format | XXX-XX-XXXX | 9XX-XX-XXXX | XX-XXXXXXX |
SSN
An SSN is issued to US citizens and to non-citizens who are authorised to work in the United States. Non-residents who are not authorised to work generally cannot get one. The SSN is the main personal tax identifier for those who qualify.
ITIN
An ITIN is issued only for federal tax purposes. It is for individuals who have a US filing requirement, or are claiming a treaty benefit or refund, but are not eligible for an SSN. An ITIN does not authorise work, does not change immigration status and does not qualify you for Social Security benefits. You apply on Form W-7 with identity and foreign-status documents, usually together with a tax return unless an exception applies. A Certifying Acceptance Agent can verify your documents so that you do not have to mail your original passport. An ITIN may expire if it is not used on a federal tax return for three consecutive years.
EIN
An EIN identifies a business. You need one to open a US business bank account, file business tax returns, hire employees and apply with payment platforms. It is free to obtain, and non-residents can get one without an SSN or ITIN using Form SS-4. See how to get an EIN without an SSN.
Which does a foreign founder need?
- To own a US LLC: an EIN. No SSN or ITIN is needed to form the LLC or obtain the EIN.
- To file the LLC's required annual forms: the EIN. Form 5472 is filed using the LLC's EIN. See our Form 5472 guide.
- To file a personal US return as a non-resident (Form 1040-NR) or claim certain treaty benefits: often an ITIN.
- To work as an employee in the US: an SSN, which requires work authorisation.
Common mistakes
- Using the owner's ITIN or SSN on business forms instead of the company's EIN
- Applying for an ITIN when it is not needed
- Letting an unused ITIN expire and then having a return delayed
- Sharing numbers with unverified third parties
Not sure which you need? Our team can advise through our Doing Business in the US guidance and formation service.
Frequently asked questions
Do I need an ITIN to get an EIN?
No. Non-residents can obtain an EIN for a US company without an ITIN or SSN by using Form SS-4.
Can an ITIN be used to work in the US?
No. An ITIN is for tax filing only and does not authorise employment.
Is an EIN the same as a tax ID number?
An EIN is a federal tax ID for businesses. ITINs and SSNs are tax IDs for individuals.
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