Taxpayer Identification Number (TIN)

Updated June 15, 2021

What Is a Taxpayer Identification Number?

A Taxpayer Identification Number (TIN) is a 9-digit number that is used by the Internal Revenue Service (IRS) for tax purposes. This number may be an individual's Social Security Number (SSN) assigned by the Social Security Administration (SSA), or another identification number assigned by the IRS, such as an Employer Identification Number (EIN).

How a Taxpayer Identification Number Works

A TIN is either assigned by the SSA or IRS, and is used as a unique identifier by the IRS for administering tax laws, including processing tax returns. For most individuals, their social security number will act as their taxpayer identification number. For most businesses, the EIN will be used as the taxpayer identification number.

Types of Taxpayer Identification Numbers

The IRS accepts several types of taxpayer identification numbers. Each of them serves a different purpose, and allows the IRS to identify how to administer tax laws for each. 

Social Security Number - SSN

U.S. citizens are assigned a social security number when they receive citizenship. This typically happens at birth, but also when someone not born in the U.S. is approved for citizenship. 

A social security number is a unique, nine-digit number that always follows the same number format of: xxx-xx-xxxx. Social security numbers are used by individuals, and possibly by sole proprietors when filing tax returns and other tax documents.

Employer Identification Number - EIN

Also known as a federal tax identification number, the Employer Identification Number (EIN) is assigned to businesses by the IRS for tax reporting purposes. It is a nine-digit number with the format of xx-xxxxxxx. 

A company can obtain an EIN by applying directly with the IRS online.

Individual Taxpayer Identification Number - ITIN

Certain nonresident and resident aliens, their spouses, and dependents who cannot get a Social Security Number (SSN) can apply for an Individual Taxpayer Identification Number (ITIN). 

This number is similar to a SSN in that it is a nine-digit number with the same format: xxx-xx-xxxx. This number is used for tax processing purposes by the IRS, and qualified individuals can apply by filling out Form W-7, IRS Application for Individual Taxpayer Identification Number.

Adoption Taxpayer Identification Number - ATIN

An Adoption Taxpayer Identification Number (ATIN) is a nine-digit number issued by the IRS for adoption tax purposes. This temporary number is for individuals who are legally adopting a U.S. citizen or resident child, but who cannot get a SSN for that child in time to file their tax return.

Applications for an ATIN number use the same Form W-7 as used for ITINs. 

Preparer Tax Identification Number - PTIN

The Preparer Tax Identification Number (PTIN) is issued to paid tax preparers who are preparing and submitting tax returns on behalf of clients. Using a PTIN is required for all paid preparers, and can be applied for online through the IRS website.

Do I Need a Tax ID?

In most cases, yes. Residents of the United States are required to have a tax identification number. Tax IDs are required for submitting tax returns, reporting income, and complying with U.S. tax laws. Many U.S. jobs require a valid TIN as well, as they must report earnings to the IRS. 

How to Get a TIN

There are several ways to acquire a TIN, depending on which number you are applying for.

Where Can I Find My Taxpayer Identification Number?

There are several places to find your taxpayer identification number. Social security numbers are usually printed on official social security cards and distributed to taxpayers, and are also on official tax documents, such as your tax returns. 

ITIN and ATIN numbers will be on your tax return, but if you need to find it for completing a tax return, then you can call the ITIN IRS hotline number at 800-829-1040. PTIN numbers are issued to tax preparers, and can be accessed by logging into your online PTIN account.

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All of our content is verified for accuracy by Rachel Siegel, CFA and our team of certified financial experts. We pride ourselves on quality, research, and transparency, and we value your feedback. Below you'll find answers to some of the most common reader questions about Taxpayer Identification Number (TIN).

How are TINs Different from Social Security Numbers?

A taxpayer identification number is exclusively used by the IRS for administering tax laws, while a social security number is multi-purpose. 

Your SSN is a unique identifier that can be used for tax reporting, as well as applying for bank accounts, credit cards, a mortgage, and other financial products. A social security number also is used to verify the identity of a U.S. citizen, track their reported income, as well as calculate social security benefits.

Rachel Siegel, CFA
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Rachel Siegel, CFA is one of the nation's leading experts at ensuring the accuracy of financial and economic text.  Her prestigious background includes over 10 years of experience in creating professional financial certification exams and another 20 years of college-level teaching.

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