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What is the difference between an EIN, TIN, and ITIN?

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In a Nutshell

The acronyms EIN, TIN, and ITIN are used by the IRS to identify the different types of tax ID numbers. The main difference between an EIN and an ITIN or TIN is that an EIN is used for business entities while an ITIN is used for individuals. TIN is an umbrella term for the various kinds of taxpayer identification numbers.

Written by Kristin Turner, Harvard Law Grad
Updated March 22, 2023

What Is a TIN?

A Taxpayer Identification Number (TIN) is used by the Internal Revenue Service (IRS) in U.S. tax law administration. Your TIN is issued either by the Social Security Administration (SSA) or by the IRS. A TIN is used on tax returns, tax statements, and other tax-related documents.

There are a few types of TIN numbers that all serve different purposes. Below, we’ll talk about Employer Identification Numbers and Individual Taxpayer Identification Numbers in more detail.  

What Is an Employer Identification Number (EIN)?

An EIN is a nine-digit number the IRS uses to identify business entities like corporations and LLCs for tax purposes. EIN’s are also known as federal tax identification numbers which are used on Form 1041: U.S. Income Tax Return for Estates and Trusts to report income from estates and trusts. 

The main thing that separates an EIN from a TIN is that an EIN is for a business while a TIN is for an individual.

How Do I Get an EIN?

There are four different ways you can receive an employer identification number/federal tax ID.

1. Apply for an EIN online:

The quickest way to get an EIN is by applying online through the IRS website. This also allows you to pay with a credit card. If your business, office, or agency is located in the United States can use the EIN online application. When you apply for an EIN online, you will receive your ID number immediately. 

2. Apply for an EIN by mail:

You can also download and complete Form SS-4 to send it by mail. If your business needs a new employer ID number, one will be assigned and mailed to you. When you apply for an EIN by mail, you will receive your ID number in four weeks. [1]

3. Apply for an EIN by phone:

Applying by phone is a great option for non-resident alien applicants. If you are an international EIN applicant, you can call 1-267-941-1099 to obtain your EIN number. If you’re the one making the phone call, you need to be authorized to receive the EIN for your business entity. 

The person applying by phone also needs to be able to answer any questions concerning the SS-4 form. Typically, it is the business owner who would make this phone call. 

4. Apply for an EIN by fax: Finally, you can fax your completed Form SS-4 application to the IRS. 

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What Is an Individual Taxpayer Identification Number (ITIN)?

An ITIN is a nine-digit tax ID number that the IRS uses to identify individuals for personal tax purposes. ITINs are only assigned to individuals who are required to have taxpayer identification but are ineligible to get a Social Security Number (SSN).

How Do I Get an ITIN?

If you need an ITIN, you will need to complete IRS Form W-7: IRS Application for Individual Taxpayer Identification Number. This form requires documentation of foreign/immigrant status and identification documentation and can be brought to an IRS walk-in office or to an authorized Acceptance Agent.

Important: You cannot claim earned income credit using an ITIN.

Other Tax Identification Numbers

Social Security number (SSN)

A Social Security number (SSN) is an individual identification number. Social security cards are issued by the Social Security Administration (SSA). Social Security numbers are nine-digit ID numbers in the format: xxx-xx-xxxx. 

To apply for a Social Security number you must fill out and file Form SS-5: Application for a Social Security Card. 

Adoption Taxpayer Identification Number (ATIN)

An Adoption Taxpayer Identification Number (ATIN) is issued by the IRS to individuals who are in the process of legally adopting a child who is a U.S. citizen or U.S. resident. An ATIN is a temporary nine-digit number that adopters use for adding dependents when filing taxes.  

You can apply for an ATIN by filing Form W-7A: Application for Taxpayer Identification Number for Pending U.S. Adoptions. 

Preparer Tax Identification Number (PTIN)

A PTIN is used by individuals who are paid tax preparers. If you are someone who prepares tax forms, you will need to add your PTIN to all of the tax returns you prepare. If you need a new PTIN, you can apply for one through the IRS sign-up system


Written By:

Kristin Turner, Harvard Law Grad


Kristin is a recipient of Harvard Law School’s Public Welfare Foundation A2J Tech Fellowship. At Harvard Law, she served as a member of the Harvard Defenders, the Women’s Law Association, and the Harvard Law Negotiation Review. She was the 2016 – 2017 president of the Harvard Bla... read more about Kristin Turner, Harvard Law Grad

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