Definitions - Government Issued Numbers: EFIN, ERO, ETIN, EIN, ITIN, PTIN, and TIN

Taxpayer Identification Number (TIN). A general term referring to any of the numbers issued by the IRS or Social Security Administration to identify taxpayers. For individual filers, this usually refers to the taxpayer's Social Security Number or ITIN (if the taxpayer does not have an SSN). Other TINs include the identification numbers listed below, as well as the Adoption Taxpayer Identification Number (ATIN).

Electronic Filing Identification Number (EFIN). A 6-digit identification number assigned by the IRS to accepted applicants for participation in IRS e-file.

Electronic Return Originator (ERO). An Authorized IRS e-file Provider that originates the electronic submission of returns to the IRS.

Electronic Transmitter Identification Number (ETIN). A 5-digit identification number assigned by the IRS to a participant in IRS e-file that performs activity of transmission and/or software development. NOTE: TaxAct has an ETIN. If a customer will not transmit their own returns directly to the IRS, they will not use their ETIN.

Employer Identification Number (EIN). The EIN is a 9-digit number that the IRS issues. It is used to identify the tax accounts of employers and certain others who have no employees.

Individual Taxpayer Identification Number (ITIN). A 9-digit tax processing number that became available on July 1, 1996, for certain nonresident and resident aliens, their spouses, and dependents. The ITIN is only available from the IRS for those individuals who cannot obtain a Social Security Number (SSN). To obtain an ITIN, complete IRS Form W-7 Application for IRS Individual Identification Number.

Preparer Tax Identification Number (PTIN). An 8-digit identification number which must also contain a P at the beginning. Anyone who prepares or assists in preparing federal tax returns for compensation must have a valid PTIN before preparing returns. All enrolled agents must also have a PTIN. The PTIN cannot be used in place of the Employer Identification Number (EIN) of the tax preparation firm.

Site Identification Number (SIDN). An 8 digit identification number that Starts with the letter S, assigned by SPEC to identify each VITA/TCE site.  The SIDN is used on every return prepared by any of the volunteers at a particular VITA site in place of a PTIN which is only for use by paid preparers. A paid Preparer would not have a SIDN.