The Internal Revenue Service (IRS) and Social Security Administration (SSA) issue five primary types of tax identification numbers, each serving distinct purposes for different categories of taxpayers.
Social Security Numbers (SSNs) The SSN stands as the most widely used tax identifier in the United States. Created in 1936, SSNs track earnings histories of U.S. workers for Social Security benefit calculations. These nine-digit identifiers follow the format XXX-XX-XXXX and enable government agencies to monitor individual records while allowing businesses to track financial information.
Employer Identification Numbers (EINs) Also known as federal tax identification numbers, EINs follow a XX-XXXXXXX format. Businesses need an EIN specifically for:
- Operating partnerships or corporations
- Managing employment taxes
- Opening business bank accounts
- Filing excise tax returns
Individual Taxpayer Identification Numbers (ITINs) ITINs serve foreign individuals who cannot obtain SSNs but must file U.S. taxes. These numbers always begin with “9” and follow the same nine-digit format as SSNs. The IRS issues ITINs to:
- Nonresident aliens claiming tax treaty benefits
- Resident aliens filing U.S. tax returns
- Dependents of U.S. citizens living abroad
Adoption Taxpayer Identification Numbers (ATINs) ATINs provide temporary nine-digit identifiers for children being adopted when prospective parents cannot obtain the child’s SSN during the adoption process.
Preparer Tax Identification Numbers (PTINs) Starting January 1, 2011, all paid tax preparers must use PTINs when filing returns. Unlike optional usage in previous years, PTINs have become mandatory for professional tax preparation services.
Each TIN type requires specific documentation for application. Furthermore, the IRS maintains strict verification processes, particularly for ITINs, where applicants must submit original documents or agency-certified copies to prove identity and foreign status. Most notably, the Social Security Administration has issued more than 450 million original SSNs as of December 2008.