SSN vs ITIN vs EIN

An SSN, ITIN, and EIN are all nine-digit tax identification numbers used in the United States, but they serve entirely different purposes. An SSN and ITIN identify individual people for tax purposes, while an EIN identifies a business entity.

The differences and specific business formations that use them include:

1. Social Security Number (SSN)

• What it is: Issued by the Social Security Administration to U.S. citizens, permanent residents, and temporary working residents. It is a lifelong personal identifier used to track employment, personal income, credit, and government benefits.

• Business Formations Used For:

  • Sole Proprietorships: Owners who have an SSN operate their business under their own personal tax ID, using it for all personal and business tax filings.

  • Single-Member LLCs: If you are the sole owner, you can often use your SSN for tax reporting unless you choose to have the LLC taxed as a corporation.

2. Individual Taxpayer Identification Number (ITIN)

• What it is: Issued by the IRS to non-U.S. citizens or residents who need to comply with U.S. tax laws but are ineligible for an SSN. It does not grant permission to work in the U.S. or qualify the holder for Social Security benefits.

• Business Formations Used For:  An ITIN functions differently depending on the structure:

  • Sole Proprietorship: You can operate as a sole proprietor using your ITIN on your personal tax return to report business income. However, to open a business bank account or hire employees, you will also need to apply for an Employer Identification Number (EIN) from the IRS.

• Limited Liability Company (LLC): You can form and own an LLC in any U.S. state using your ITIN. While you can register the LLC with your ITIN, most banks will require you to get an EIN before they let you open a U.S. business bank account.

• Corporation: You can form a C-Corporation using an ITIN. However, ITIN holders are not eligible to form an S-Corporation. As with an LLC, you will need to get an EIN to register the corporation for corporate taxes and open a business bank account.

3. Employer Identification Number (EIN)

• What it is: Issued by the IRS, this is essentially a "Social Security Number for a business". It is used strictly to identify a business entity for tax, hiring, and banking purposes.

• Business Formations Used For:

  • Corporations (C-Corp or S-Corp): Required for all corporate business formations to file corporate tax returns.

  • Partnerships: Required to file partnership tax returns and issue K-1s to partners.

  • Multi-Member LLCs: Required to file partnership-level tax returns.

  • LLCs with Employees: Required if the business plans to hire W-2 employees, run payroll, or establish business credit.

  • Sole Proprietorship: While you aren't legally required to have one unless you have employees, it is entirely optional, free to get, and highly recommended to protect your personal Social Security number.