The Statement of Taxpayer Identification Number (TIN) is a document or form issued by the Internal Revenue Service (IRS) that contains the taxpayer's social security number (SSN) or employer identification number (EIN). It is used to report income, pay taxes, and identify taxpayers to the IRS. The TIN is also used by other government agencies and businesses to verify the identity of taxpayers. There are two types of TIN: the Social Security Number (SSN) and the Employer Identification Number (EIN). The SSN is issued to individuals for tax reporting purposes, while the EIN is used to identify a business or organization for tax reporting.