Main / Glossary / Taxpayer Identification Number (TIN)

Taxpayer Identification Number (TIN)

A taxpayer identification number (TIN) is a unique identifier assigned to individuals and businesses by the Internal Revenue Service (IRS) in order to track and administer tax liabilities. This number is used to identify taxpayers on various tax forms, returns, and correspondence with the IRS. The TIN serves as a critical component of the tax system, enabling the IRS to accurately process and record tax-related transactions.


For individuals, the TIN is typically the Social Security Number (SSN). The SSN is a nine-digit number assigned to U.S. citizens, permanent residents, and temporary residents who are authorized to work in the United States. It serves as both an identification number and a means of tracking a person’s earnings for purposes of taxation and social security benefits.

– Taxpayer Identification Number – SSN: The SSN is assigned to individuals by the Social Security Administration (SSA) and is used by the IRS as the primary identification number for tax purposes. It is associated with a person’s legal name, date of birth, and citizenship or immigration status. The SSN is required to file tax returns, claim deductions, and report income and employment information.


For businesses, the TIN is known as the Employer Identification Number (EIN). The EIN is a nine-digit number assigned to businesses, including corporations, partnerships, limited liability companies (LLCs), and sole proprietorships, for tax filing and reporting purposes. It serves as a unique identifier for each business entity, facilitating the tracking of tax liabilities, income, and employment information.

– Taxpayer Identification Number – EIN: The EIN is obtained by applying to the IRS using Form SS-4, Application for Employer Identification Number. Businesses use this number when filing tax returns, making payments, and fulfilling reporting obligations to the IRS. It also enables businesses to establish credit, open bank accounts, and engage in financial transactions.

Not-for-Profit Organizations:

Not-for-profit organizations, such as charities, religious institutions, and educational institutions, also require a TIN. However, they are assigned a specific type of TIN known as the Taxpayer Identification Number – Tax Exempt Organization (TIN-EO). This identifier is used by the IRS to grant tax-exempt status to qualifying organizations.

Responsibilities and Importance:

Having a TIN is not only mandatory but also crucial for individuals and businesses as it enables compliance with tax laws and regulations. The TIN allows the IRS to accurately track income, verify tax returns, apply credits and deductions, and maintain tax records. Failure to provide or use a valid TIN can result in penalties, delays in processing returns, and the denial of tax benefits.

Safeguarding TINs:

Given the sensitive nature of the information associated with TINs, it is of utmost importance to protect them from unauthorized access or disclosure. Individuals and businesses are encouraged to maintain the confidentiality of their TINs and refrain from sharing them with unauthorized parties. Additionally, organizations that collect TINs are required to implement safeguards to protect this information from potential breaches or misuse.

In conclusion, a taxpayer identification number (TIN) is a unique identifier assigned by the IRS to individuals, businesses, and not-for-profit organizations for tax-related purposes. It is essential for accurately tracking and administering tax obligations, ensuring compliance with tax laws, and protecting sensitive information.