A Taxpayer Identification Number (TIN) is an identification number used by the Internal Revenue Service (IRS). This is the number commonly used to file your tax return.
If you are an individual, your TIN is usually your Social Security Number (SSN), which is issued by the Social Security Administration (SSA). If you don’t qualify for an SSN, you may have an Individual Taxpayer Identification Number (ITIN), which is issued by the IRS.
If you are a business entity, a trust, or an Estate, your TIN is usually your Employer Identification Number (EIN), which is issued by the IRS.