Defined by the IRS:
What is an enrolled agent? An enrolled agent is a person who has earned the privilege of practicing, that is, representing taxpayers, before the Internal Revenue Service. Enrolled agents, like attorneys and certified public accountants (CPAs), are unrestricted as to which taxpayers they can represent, what types of tax matters they can handle, and which IRS offices they can practice before.
To become an Enrolled Agent an applicant must pass the Special Enrollment Examination or present evidence of qualifying experience as an Internal Revenue Service employee. A background check, including a review of the applicant’s tax compliance, is conducted. The IRS also requires Enrolled Agents to complete 72 hours of continuing professional education every three years.
The position of Enrolled Agent was created as a reaction to fraudulent war loss claims in the wake of the American Civil War. Unlike the highly trained, tested, and continually educated professionals of today, the first “EAs” were appointed with little or no qualifications other than a minimal background in bookkeeping.
According to the National Association of Enrolled Agents there are currently about 46,000 practicing EAs in the United States.