# What Is a Tax Identification Number (TIN)?

> **Definition**
>
> A Tax Identification Number (TIN) is a unique number assigned to taxpayers and used by the Internal Revenue Service (IRS) in its administration of the nation's tax system.

## What Is a Tax Identification Number (TIN)?

A Tax Identification Number (TIN) is a nine-digit number that the [Internal Revenue Service (IRS)](https://www.investopedia.com/terms/i/irs.asp) uses to identify taxpayers. Also known as a Taxpayer Identification Number, one type of TIN is a [Social Security number (SSN)](https://www.investopedia.com/terms/s/ssn.asp).

### Key Takeaways

*   TINs are nine-digit numbers assigned to taxpayers.
*   The IRS issues all U.S. TINs except for Social Security numbers, which are issued by the Social Security Administration.
*   Tax filers must include their TIN on tax-related documents and when claiming benefits.

![Tax Identification Number ](https://www.investopedia.com/thmb/ODQykASltOkoZ4uVTYIX1cOcVhQ=/1500x0/filters:no_upscale():max_bytes(150000):strip_icc()/tax-indentification-number-tin.asp-30a92e7158164a03921914a81532f9ab.jpg)

*For most individuals, their TIN is their Social Security number (SSN). A foreign person who doesn't have an SSN must use an individual taxpayer identification number (ITIN). — Investopedia / Ellen Lindner*

## Types of TINs

*   **Social Security number (SSN):** This is the most common TIN issued to U.S. citizens, permanent residents, and certain temporary residents by the [Social Security Administration](https://www.investopedia.com/terms/s/ssa.asp). It's formatted as XXX-XX-XXXX. The SSN is required to secure legal employment in the U.S. and to receive Social Security benefits and other government services.
*   **Individual Taxpayer Identification Number (ITIN):** This is issued by the IRS to certain nonresident and resident aliens, their spouses, and their dependents when they're ineligible for SSNs. It's arranged in the same format as an SSN (XXX-XX-XXXX). The [ITIN](https://www.investopedia.com/getting-personal-loans-itin-7643887) always begins with a 9. The applicant must complete Form W-7 and submit documents supporting their resident status to get an ITIN.
*   **Employer Identification Number (EIN):** This is used by the IRS to identify corporations, trusts, and estates that must pay taxes. Just like SSNs, EINs are nine digits but they're read as XX-XXXXXXX. Those who qualify for an [EIN](https://www.investopedia.com/terms/e/employer-identification-number.asp) must apply for and use it to report their capital gains and income for taxation purposes.
*   **Adoption Tax Identification Number:** The ATIN applies to domestic adoptions when the adoptive parents cannot obtain the child's SSN to complete their tax returns. The child must be a U.S. citizen or permanent resident to qualify and the adoption must be pending.
*   **Preparer Tax Identification Number:** The IRS requires a PTIN on each tax return that's filed. Any tax preparer who charges to complete all or part of a tax return for another individual must have and use a PTIN.  
    

> **Important**
>
> A child must have an SSN before a parent can claim them as a dependent for income tax purposes.

## When Is a TIN Required?

A TIN identifies individuals, [corporations](https://www.investopedia.com/terms/c/corporation.asp), and entities such as [nonprofit organizations (NPOs)](https://www.investopedia.com/terms/n/non-profitorganization.asp). The TIN is mandatory for anyone filing annual [tax returns](https://www.investopedia.com/terms/t/taxreturn.asp) with the IRS and the agency uses it to track taxpayers. In addition:

*   **For credit:** Banks and other lenders require SSNs on credit applications. This information is then relayed to the credit bureaus to ensure that the right person fills out the application. The [credit reporting agencies](https://www.investopedia.com/terms/c/credit-reporting-agency.asp) also use TINs, notably SSNs, to report and track an individual's credit history.
*   **For employment:** Employers require an SSN from anyone applying for employment. This ensures that the individual is authorized to work in the U.S. Employers verify the numbers with the issuing agency.
*   **For state agencies:** Businesses also need state identification numbers for tax purposes to file with their state tax agencies. State taxing authorities issue the I.D. number directly to the filer.

## Global TINs

Almost every country uses TINs for various reasons. For example, Canada uses [Social Insurance Numbers (SINs)](https://www.investopedia.com/ask/answers/102915/does-canada-have-social-security-numbers.asp) for employment, taxation, the provision of benefits, and credit purposes.

The SIN is a nine-digit unique identifier that's formatted as XXX-XXX-XXX. Countries in the European Union also use TINs that help government agencies identify taxpayers and allow entities to invest money across the EU.

## Who Needs a Tax Identification Number?

To work in the U.S. or file taxes with the IRS, individuals need a TIN. A TIN allows individuals to receive benefits or services offered by the government and to report their taxes. Corporations, trusts, and nonprofits also use TINs.

## Are TINs Available Online?

The agency that issues a TIN will provide an official document with an identifier. TINs are not available online because they are sensitive information.

## Is a Taxpayer Identification Number the Same As a Social Security Number?

A Social Security number is a type of TIN. It allows individuals to seek employment in the U.S., to obtain loans and credit from banks and other lenders, and to file income tax returns.

## The Bottom Line

A TIN is necessary to have to work in the U.S. and file a tax return. A Social Security number is a type of TIN used by individuals. Corporations, trusts, and nonprofit organizations also use TINs.

> **Article Sources**
>
> 1.  Social Security Administration. "[Social Security Number & Card](https://www.ssa.gov/ssnumber/)."
>     
> 2.  Internal Revenue Service. "[Individual Taxpayer Identification Number](https://www.irs.gov/individuals/individual-taxpayer-identification-number)."
>     
> 3.  Internal Revenue Service. "[Employer Identification Number](https://www.irs.gov/businesses/small-businesses-self-employed/employer-id-numbers)."
>     
> 4.  Internal Revenue Service. "[Adoption Taxpayer Identification Number](https://www.irs.gov/individuals/adoption-taxpayer-identification-number#)."
>     
> 5.  Internal Revenue Service. "[PTIN Requirements for Tax Return Preparers](https://www.irs.gov/tax-professionals/ptin-requirements-for-tax-return-preparers)."
>     
> 6.  Internal Revenue Service. "[Qualifying Child Rules](https://www.irs.gov/credits-deductions/individuals/earned-income-tax-credit/qualifying-child-rules)."
>     
> 7.  Internal Revenue Service. "[U.S. Taxpayer Identification Number Requirement](https://www.irs.gov/individuals/international-taxpayers/us-taxpayer-identification-number-requirement)."
>     
> 8.  Government of Canada. "[Social Insurance Number Overview](https://www.canada.ca/en/employment-social-development/services/sin.html?utm_campaign=not-applicable&utm_medium=vanity-url&utm_source=canada-ca_social-insurance-number)."
>     
> 9.  European Commission. "[Taxpayer Identification Number (TIN)](https://ec.europa.eu/taxation_customs/business/tax-cooperation-control/administrative-cooperation/tax-identification-numbers-tin_en)."