What Is a Tax Identification Number (TIN)? Definition and Guide

A tax or taxpayer identification number, also known as a TIN for short, is a number issued to individuals and organizations to track tax obligations and payments they make to the Internal Revenue Service (IRS). It is issued by the federal government. A TIN can be assigned by the Social Security Administration for individuals, or by the IRS for businesses and other organizations.

A tax or taxpayer identification number, also known as a TIN for short, is a number issued to individuals and organizations to track tax obligations and payments they make to the Internal Revenue Service (IRS). It is issued by the federal government. A TIN can be assigned by the Social Security Administration for individuals, or by the IRS for businesses and other organizations.

Types of tax ID numbers

A TIN is a generic term and refers to several different kinds of identifying numbers, which include:

• A social security number issued to an individual
• An Individual Taxpayer Identification Number (ITIN), issued to non-U.S. citizens currently residing, and often working, in the U.S.
• An Employer Identification Number (EIN) issued to businesses and non-profit organizations
• An Adoption Taxpayer Identification Number (ATIN), for children in the process of being adopted from outside the U.S.
• A Preparer Taxpayer Identification Number, to identify accountants and firms involved with tax document preparation

Small businesses require a TIN, in the form of an Employer Identification Number, in order to issue payroll and make tax payments. To apply for an EIN, the IRS requires you to complete a Form SS-4.

A TIN is required on all tax documents, such as quarterly or estimated payments and annual filings.

State tax ID numbers

Some states also issue their own business identification numbers, in addition to the IRS identifier. Currently, those states are:

• Massachusetts
• New York
• South Carolina

In those states, business need a state tax ID number and a federal tax ID number. Learn more about state TINs here.

Tax Identification Number FAQ

Is tax identification number the same as SSN?

No, a Tax Identification Number (TIN) is not the same as a Social Security Number (SSN). A TIN is a unique set of numbers assigned by the Internal Revenue Service (IRS) to individuals and businesses for tax purposes. An SSN is a 9-digit number assigned by the Social Security Administration (SSA) to U.S. citizens, permanent residents, and certain temporary residents for the purpose of tracking individual income and benefits.

How do I find my taxpayer identification number?

Your taxpayer identification number is typically your Social Security Number (SSN), but if you are self-employed you may also have an Employer Identification Number (EIN). To find your taxpayer identification number, you can check your income tax return from the previous year, your Social Security card, or contact your local IRS office.

Does everyone have a tax ID number?

No, not everyone has a tax ID number. Only individuals or businesses that are required to pay taxes are assigned a tax ID number.

Is a tax ID number the same as an EIN?

Yes, an EIN (Employer Identification Number) is the same as a Tax ID Number.