TIN, ITIN, and EIN in the U.S.: Key Differences, When You Need Them, and How to Apply

Understanding the difference between TIN, ITIN, and EIN is essential if you plan to operate or expand your business in the United States. While these acronyms may look similar, each one identifies a different type of taxpayer and is used for specific purposes: individuals, businesses, or particular situations. Choosing and obtaining the right number impacts your banking, tax filings, and compliance with clients and suppliers.

What Is a TIN (Taxpayer Identification Number)?

TIN is the umbrella term for “Taxpayer Identification Numbers” used by the U.S. tax authority. Within this category, the main types are:

• SSN (for individuals who qualify)
• ITIN (for individuals who cannot obtain an SSN but need tax identification)
• EIN (for businesses and certain entities)

In practice, when you’re asked for your “TIN,” make sure to clarify whether they mean SSN, ITIN, or EIN, depending on the process.

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SSN vs. ITIN vs. EIN: A Quick Guide (No Table Needed)

• SSN (Social Security Number): A personal number for those who qualify. It’s used for employment, benefits, and individual tax purposes. If you’re not eligible for an SSN, you cannot obtain one.
• ITIN (Individual Taxpayer Identification Number): A number for individuals not eligible for an SSN who need tax identification to file returns, claim treaty benefits, or appear on a tax declaration. It is requested using Form W-7/W-7(SP) and requires proof of identity and foreign status. ITINs expire if not used on tax returns for three consecutive years (but can be renewed).
• EIN (Employer Identification Number): A business tax identification number—the equivalent of your company’s “SSN.” You’ll use it for banking, hiring, permits, supplier relationships, tax filings, and more. It is requested with Form SS-4 (also available in Spanish).

When Do You Need Each One?

Typical SSN Scenarios (not handled by Openbiz)

• Working legally in the U.S.
• Accessing Social Security benefits and building personal credit history.

If you don’t qualify for an SSN, your alternative for tax purposes is the ITIN.

Typical ITIN Scenarios

• You don’t have an SSN and aren’t eligible for one, but you must file a federal tax return or identify yourself with the IRS.
• You are a foreign member of an LLC or a shareholder and need to report your share of income.
• You require a TIN to apply treaty benefits or manage proper tax withholdings.

The usual process involves completing Form W-7/W-7(SP), attaching documentation, and generally submitting it alongside a federal tax return (with exceptions allowed).
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Typical EIN Scenarios

• Forming and operating a company (LLC, C-Corp) and dealing with banks, payment gateways, marketplaces, or clients requiring tax ID.
• Hiring employees, running payroll, and managing withholdings.
• Other entities like trusts or estates may also require an EIN.

Common Mistakes

• Confusing “Tax ID” as a single number. Always check if you need SSN, ITIN, or EIN.
• Using an SSN for business matters when an EIN is required. This exposes personal data and may cause banking rejections.
• Applying for an ITIN without proper documentation. Form W-7 requires evidence and usually a federal return.
• Forgetting to renew your ITIN. After three years of non-use, it expires, delaying refunds or filings.
• Not updating EIN information. Address changes or changes to the “responsible party” must be reported.

Best Practices for International Founders

• Separate identities: Use EIN for the company and ITIN/SSN for your personal situation.
• Plan from day one: Define your entity’s tax classification (e.g., disregarded LLC, corporation) and how it will affect your tax filings.
• Document everything: Articles, operating agreement, responsible parties, addresses, and business activity. Clear records help with banks and suppliers.
• Track deadlines: Annual tax returns, renewals, and required updates.
• Avoid inconsistencies: Keep your company’s name, address, and activity consistent across all forms and accounts.

At Openbiz, we focus on what we truly do: creating your company in the U.S. and managing its administrative and tax matters. We guide you to secure the correct EIN for your entity and clearly explain when you may need an ITIN personally to comply with tax obligations. Plus, we provide support in Spanish and adapt the process to your case—without unnecessary jargon.

Frequently Asked Questions

Can I run my business with my personal SSN?
If you are a sole proprietor without a formal entity, some people do. But once you form an LLC or C-Corp, the standard is to use an EIN to separate identities, protect personal data, and meet banking and supplier requirements.

I’m a nonresident and plan to open an LLC. Do I need ITIN, EIN, or both?
The company will need an EIN. You, as an individual, may need an ITIN to file your personal taxes related to the LLC’s pass-through income (depending on its classification) or to apply treaty benefits. It depends on your situation.

How do I apply for an ITIN?
By submitting Form W-7/W-7(SP) with proof of identity and foreign status. It’s normally sent with a federal tax return or justified with an exception. It can also be processed in person or through authorized acceptance agents.

How do I apply for an EIN?
By filing Form SS-4/SS-4(SP). Foreign owners can obtain it as well. The application identifies the responsible party and requires a brief description of the activity.

Does the ITIN expire?
Yes. If not used on a federal return for three consecutive years, it expires and must be renewed before filing again.

Can I obtain an SSN if I am a foreigner without work authorization?
No. If you don’t qualify, your option for tax matters is the ITIN.

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