TIN is a unique nine-digit number for identifying an individual, business or other entity in tax returns and additional documents filed with the IRS.
TIN is identification number used by IRS in the administration of tax laws. Each person or entity must apply for TIN. Then, assigning agency assigns the applicant a special number.
Individuals are assigned TINs in the form of Social Security numbers (SSN). Other types of tax identification numbers include the EIN, ITIN, ATIN, and PTIN.
The Internal Revenue Service issues all Taxpayer Identification Number except for social security numbers, which are issued by the Social Security Administration.
Tax filers must include their tax identification number on tax-related documents and when claiming benefits. TINs are also required when applying for credit and employment.
The agency that issues your TIN provides you with an official document with your unique identifier. If you can't remember or lose your documents, you should contact the issuing agency to get your TIN again.