What Is a Tax Identification Number (TIN)?

A Tax Identification Number (TIN) is a nine-digit number used as a tracking number by the U.S. Internal Revenue Service (IRS) and is required information on all tax returns filed with the IRS. All U.S. tax identification numbers (TIN) or tax id numbers are issued directly by the IRS except social security numbers (SSN), which are issued by the Social Security Administration (SSA). Foreign tax identifying numbers (foreign TIN) are also not issued by the IRS; rather, they are issued by the country in which the non-U.S. taxpayer pays taxes.


Tax Identification Number (TIN)

Key Takeaways

  • Tax identification numbers are nine-digit tracking numbers used by the IRS following tax laws.
  • The IRS issues all U.S. tax id numbers except the social security number (SSN), which is issued by the Social Security Administration (SSA).
  • There are different types of tax identification numbers, such as the employer identification number (EIN), individual tax identification number (ITIN), and adoption tax identification number (ATIN).
  • Tax filers must include their tax identification number on tax-related documents and when claiming benefits.

Understanding the Tax Identification Number (TIN)?

Tax identification numbers or taxpayer-identification numbers come in several different forms. Individuals are assigned TINs in the form of Social Security Numbers (SSNs), whereas businesses (e.g., corporations and partnerships) are assigned employer identification numbers (EINs). SSNs are tax identification numbers for individuals, and the Social Security Administration (SSA) issues them in the format of XXX-XX-XXXX. Employer tax ID numbers are also nine digits long, but they are read as XX-XXXXXXX. Trusts, fiduciaries, and other non-business entities are assigned straight tax ID numbers. Other types of TINs include the Individual Taxpayer Identification Number (ITIN), the Adoption Taxpayer Identification Number (ATIN), and the Preparer Tax Identification Number (PTIN).

The IRS uses tax identification numbers to track taxpayers. Filers must include the number of tax-related documents and when claiming benefits.

Types of Tax Identification Numbers (TIN)

Social Security Numbers (SSN)

The social security number (SSN) is the most common tax identification number. SSNs are issued to U.S. citizens, permanent residents, and certain temporary residents. The SSN is required to secure legal employment in the U.S., as well as receive social security benefits and other government services. A child must have an SSN before a parent can claim them as a dependent for income tax purposes; so, most parents voluntarily apply for the number on behalf of their children. A child with an ITIN can be claimed as a dependent. The SSA processes applications for free, but there are also fee-based services that offer to complete applications for new parents.

Individual Taxpayer Identification Number (ITIN)

The IRS issues the Individual Taxpayer Identification Number (ITIN) to certain nonresident and resident aliens, their spouses, and their dependents when ineligible for SSNs. Arranged in the same format as an SSN (XXX-XX-XXXX), the ITIN begins with a 9. To get an individual tax id number, the applicant must complete Form W-7 and submit documents supporting his or her resident status. Certain agencies—including colleges, banks and accounting firms—often help applicants obtain their ITIN. 

Employer Identification Numbers (EIN)

The IRS uses the Employee Identification Number (EIN) to identify corporations, trusts, and estates that must pay taxes. These groups must apply for the number and use it to report their income for taxation purposes. Applying for an EIN is free, and businesses can obtain one immediately. 

Adoption Tax Identification Numbers

The ATIN only applies to domestic adoptions when the adoptive parents cannot obtain the child's SSN to complete their tax returns promptly. To qualify, the child must be a U.S. citizen or permanent resident and the adoption must be pending.

Preparer Tax Identification Number

As of Jan. 1, 2011, the IRS required the listing of a PTIN on each return filed. Before this date, the use of the PTIN was optional. Any preparer that charges to complete all or part of the tax return for another individual must have and use the PTIN.