Taxpayer Identification Number

A taxpayer identification number is a number the IRS uses to keep track of all taxpaying entities in the U.S., both individuals and businesses. Every taxpayer identification number is issued by the IRS except the Social Security number, which is issued by the Social Security Administration. Most individuals use their Social Security as their taxpayer identification number. Other kinds of a taxpayer identification number include the Employer Identification Number (EIN) for businesses, the Individual Taxpayer Identification Number (ITIN) for nonresident and resident aliens, their spouses, and dependents, the Adoption Taxpayer Identification Number (ATIN) for people in the process of gaining U.S. citizenship, and the Preparer Taxpayer Identification Number (PTIN) for paid tax preparers who don't want to disclose their personal Social Security numbers on the returns they prepare. Estates, partnerships, and trusts also use the EIN. All returns, statements, and other tax documents filed with the IRS and state taxing authorities must include a taxpayer identification number. All taxpayers who claim dependents on their income tax form must include the taxpayer identification number of each dependent.