What is a tax ID number?

A tax identification number (TIN) is a unique nine-digit number assigned to you for identification by the Internal Revenue Services (IRS). You need a TIN to file your tax returns and other official purposes. Either the Social Security Administration or the IRS assigns this number to you. 

There are different types of TINs:

Individual taxpayer identification number (ITIN) is a 9-digit tax ID number for nonresident or resident aliens, spouses, and dependents who cannot get a Social Security number (SSN). The IRS issues the ITIN so that they can pay their taxes easily.

There is a Tax ID for businesses called the employer identification number (EIN). People in the process of adopting a child are assigned a temporary adoption taxpayer identification number (ATIN). The IRS assigns this number in case the adopting parents can’t get a social security number for the child in time to file their taxes. This number identifies the child and is required for the parent to claim the child as a dependent. 

A preparer tax identification number (PTIN) is for anyone who prepares or helps in preparing federal tax returns for compensation. These people are given a PTIN by the IRS and must put the number on their client’s tax returns.