Tax ID Number vs EIN vs ITIN: Which One You Need

“Tax ID number” is a general term, not the name of one specific credential. In the federal tax system, a taxpayer identification number (TIN) is a number the IRS uses to administer tax laws. TINs include Social Security numbers (SSNs), employer identification numbers (EINs), individual taxpayer identification numbers (ITINs), adoption taxpayer identification numbers (ATINs), and preparer taxpayer identification numbers (PTINs).

For most individuals, the appropriate TIN is an SSN. An EIN generally identifies a business, tax-exempt organization, estate, trust, or other entity. An ITIN is for an individual who has a federal tax purpose but is not eligible for an SSN. Consequently, asking whether you need a “Tax ID, EIN, or ITIN” mixes a broad category with two specific types of numbers.

How Tax ID Numbers, EINs, and ITINs Differ

The correct number depends first on who or what must be identified. An individual filing or appearing on a federal tax document usually needs an individual TIN. A business or another entity may need an EIN. The terms are related, but they are not interchangeable.

The most important distinction is between a number identifying an individual and one identifying an entity. An owner may have an SSN or ITIN for individual tax purposes while a business has an EIN for its own federal tax activities. The business EIN does not become the owner’s personal TIN.

For a narrower comparison, see Tax ID Number vs EIN: When Each One Is Required.

Which Number Fits Your Situation?

You are an individual eligible for an SSN

For most individuals, the correct TIN is an SSN rather than an ITIN. A person who is eligible for an SSN does not need an ITIN. Applying for an SSN uses Form SS-5 and requires evidence of identity, age, and U.S. citizenship or lawful alien status.

You need an individual number but cannot obtain an SSN

An ITIN may be appropriate when an individual has a federal tax purpose but is not eligible for an SSN. It is an individual number, not a business substitute for an EIN.

An ITIN’s role is limited. It does not authorize U.S. employment, provide immigration status, qualify its holder for Social Security benefits, or serve as identification outside the federal tax system. Those limitations matter when deciding whether an ITIN will satisfy the purpose for which a number has been requested.

You are identifying a business or other entity

An EIN may be required for an entity with employees, specified employment or excise tax obligations, alcohol, tobacco and firearms tax obligations, or non-wage withholding paid to a nonresident alien. The IRS also lists partnerships, LLCs, corporations, tax-exempt organizations, estates, and most trusts among entities needing an EIN, although entity-specific exceptions can apply.

Business structure matters. Partnership owners can review EIN for Partnership: What General Partners Need to Know. Individuals operating without a separate entity may instead find the discussion in EIN for a Sole Proprietor: When You Need One and When You Don’t useful.

You have both individual and business tax responsibilities

Do not assume one number covers every role. Determine separately which number identifies you as an individual and which number identifies the business or entity. For example, the fact that a person has an ITIN does not turn that ITIN into the entity’s EIN. Likewise, an entity’s EIN does not replace that person’s SSN or ITIN.

How to Apply for the Correct Number

Before applying for an EIN

If you are creating an LLC, partnership, corporation, or tax-exempt organization, register or legally form it before applying for the EIN. This sequence helps ensure that the EIN application reflects the legal entity that will use the number.

The IRS issues EINs free of charge. Online EIN applications are limited to applicants whose legal residence, principal business, or principal office or agency is in the United States or a U.S. territory. Fax and mail applications use Form SS-4. EIN issuance is limited to one EIN per responsible party per day across online, telephone, fax, and mail requests.

When applying for an ITIN

Use Form W-7. Applicants generally attach a federal income tax return and documentation establishing identity and foreign status. A person who qualifies for a listed exception may provide the supporting exception documentation instead of a return.

Before beginning, confirm both parts of the eligibility test: there is a federal tax purpose, and the applicant is not eligible for an SSN. If the individual is eligible for an SSN, the proper path is not an ITIN application.

When applying for an SSN

An individual SSN application uses Form SS-5. The required evidence addresses identity, age, and U.S. citizenship or lawful alien status. Because the Social Security Administration issues SSNs, an SSN and an IRS-issued ITIN follow different application paths.

Common Classification Problems to Avoid

• Treating “Tax ID” as a separate federal number: The phrase may refer to an SSN, EIN, ITIN, or another TIN. Identify the taxpayer and purpose before selecting an application.
• Requesting an ITIN even though the person is eligible for an SSN: ITIN eligibility is restricted to individuals who are not eligible for an SSN and have a federal tax purpose.
• Using an EIN as personal identification: An EIN identifies a business or another entity for federal tax purposes; it must not replace an individual’s SSN or ITIN.
• Using an ITIN as evidence of work authorization or immigration status: An ITIN provides neither and is not identification outside the federal tax system.
• Applying for an entity’s EIN before forming the entity: An LLC, partnership, corporation, or tax-exempt organization should first be registered or legally formed.
• Assuming every TIN follows the same application procedure: EIN, ITIN, and SSN applications use different forms and supporting information.

Decision Checklist

Use these questions to narrow the choice before completing an application:

1. Who needs to be identified? Decide whether the number is for an individual or for a business, organization, estate, trust, or other entity.
2. If it is for an individual, is that person eligible for an SSN? If yes, an SSN is generally the appropriate TIN. If no, determine whether the person has a federal tax purpose that supports ITIN eligibility.
3. If it is for an entity, does an EIN requirement apply? Consider employees, the entity’s structure, and the relevant federal tax obligations.
4. Has a newly created legal entity been formed? Complete the registration or legal formation of an LLC, partnership, corporation, or tax-exempt organization before requesting its EIN.
5. Are you using the correct application? EIN fax and mail applications use Form SS-4, ITIN applications use Form W-7, and SSN applications use Form SS-5.
6. Are you expecting the number to perform a function it does not have? An EIN does not replace a personal TIN, and an ITIN does not provide work authorization, immigration status, Social Security benefits, or general identification.

In short, choose an SSN or ITIN based on the individual’s eligibility and federal tax purpose, and choose an EIN when a business or other entity needs its own federal tax identifier. “Tax ID number” describes the overall category rather than providing a fourth alternative.