All tax returns filed with the IRS must include a taxpayer identification number (TIN). For most individual taxpayers, a Social Security number is used as the TIN. For all other taxpayers, the IRS issues the TIN, the most common of which is the employer identification number (EIN), frequently referred to as the "federal tax identification number." If you are the executor of an estate, you will need an EIN to file tax returns for the estate.

EINs for Estates

Income earned by a decedent prior to death will be reported on a final Form 1040 using the decedent's Social Security number; however, income produced post-death during administration of the estate, such as interest, rents and dividends, that exceeds $600 must be reported on Form 1041 using an EIN for the estate. In the event that the total estate value exceeds certain federal thresholds (e.g. $3.5 million for date of death on or after Jan. 1, 2009), Form 706 will have to be filed using an EIN.

Apply Online

There are several ways of applying for an EIN, including on an application available on the IRS website. This is probably the most convenient way to apply as it streamlines the process to focus on the information needed when applying for an EIN for an estate. You will need your identifying information including your Social Security number to start, which will be matched to the IRS's records. Once you are identified in the records, the process involves providing identifying details for the decedent and estate and you will receive the EIN upon completion.

Form SS-4

You can also apply by mail by downloading Form SS-4 and sending it to the IRS office indicated in the instructions that accompany the form. Be aware that this is a multi-purpose form intended for use by other entities as well, such as corporations and trusts, so not all the requested information is applicable to estates. If you prefer, you can fax your completed Form SS-4 to the IRS. You will have to determine where to fax it from the information available on the IRS website as it will depend on your specific address location. The IRS indicates that a confirmation with the EIN will be returned to you via fax within four business days.

Apply by Phone

If you prefer, you can apply for an EIN by calling the IRS's Business & Specialty Tax Line: (800) 829-4933. You will be assigned an EIN immediately over the phone.

Source:

IRS.gov: Taxpayer Identification Numbers

IRS.gov: Do You Need an EIN?

IRS.gov: Apply Online for an EIN

More Information:

IRS.gov: Form SS-4 Application for Employer Identification Number