Tax Identification Number Glossary: Forms, Terms & Definitions

Key Tax Identification Terms

Taxpayer Identification Numbers (TINs) are used by tax authorities to identify individuals and entities for tax administration, reporting and compliance purposes. Explore our glossary to understand the different types of TINs, how they are used and the terminology commonly encountered in tax documentation and reporting.

Global Intermediary Identification Number

A Global Intermediary Identification Number (“GIIN”) is the identification number assigned to an entity that has registered with the IRS for chapter 4 purposes.

Social Security Number

A nine-digit U.S. identification number issued by the Social Security Administration, primarily used for employment, tax reporting, and identifying individuals for U.S. tax purposes.

Taxpayer Identification Number (TIN)

A unique number used by the IRS to identify individuals and entities for U.S. tax purposes. Types of TIN include the Social Security Number (SSN), Employer Identification Number (EIN), Individual Taxpayer Identification Number (ITIN), Adoption Taxpayer Identification Number (ATIN) and Preparer Taxpayer Identification Number (PTIN).

Individual Taxpayer Identification Number (ITIN)

An Individual Taxpayer Identification Number (ITIN) is a nine-digit number, always beginning with 9, issued by the IRS to individuals who need a U.S. taxpayer identification number but are not eligible for a Social Security Number. It is used for tax filing and reporting, including claims for tax treaty benefits, but it does not authorize work in the United States or change immigration status.

Foreign Taxpayer Identification Number

A taxpayer identification number issued by a foreign country to an individual or entity for tax purposes. It may be collected as part of U.S. tax documentation and FATCA or CRS reporting requirements.

EIN

A nine-digit number issued by the IRS to identify businesses and other entities for U.S. federal tax purposes. It is commonly used for tax reporting, filing, and identification.

TIN Validation

The process of checking a tax identification number for validity, format or consistency with available taxpayer information.