Individuals and organizations engaged in a trade or business, plus entities exempt from income tax such as religious, charitable, and educational institutions, the governments of the United States, Puerto Rico, the Virgin Islands, Guam, American Samoa, the Northern Mariana Islands, and the District of Columbia, and the agencies, instrumentalities, and political subdivisions of these governments.

References

https://www.cms.gov/apps/glossary/default.asp?Letter=E&Language=English