What Is a Tax Identification Number (TIN)?

By Frank Bass – Updated Feb 25, 2025 at 11:08 PM

Key Points

A Tax Identification Number (TIN) is required for all entities to file tax returns.
Individuals use their Social Security Number (SSN) as their TIN for personal taxes.
Businesses need unique TINs, obtained via IRS, to handle their tax obligations.

For most Americans, their identity for tax purposes is simply their individual nine-digit Social Security number. In some cases, however, another number is required. That number, known as a taxpayer identification number, is issued by the Internal Revenue Service. Read on for more information about the types of taxpayer identification numbers and the circumstances under which each type is used.

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IRS form 1040 with a calculator and pen resting on top. — Image source: Getty Images.

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About the Author

Frank Bass is a contributing Motley Fool stock market analyst and editor covering energy, healthcare, consumer, and financial sectors. Frank has decades of experience in financial journalism, holding reporting and editing roles at The Wall Street Journal, The Associated Press, and Bloomberg. He also currently edits research on the global energy transition. He holds a bachelor’s degree in journalism from Texas Tech University and is a graduate student at the University of Alaska Fairbanks. Fun Facts: Frank has hiked The Long Trail in Vermont from end to end, and currently lives in a semi-dry cabin in Interior Alaska.

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