Unemp. Ins. Code, § 135

(a) “Employing unit” means an individual or type of organization that has in its employ one or more individuals performing services for it within this state, and includes but is not limited to, the following individuals and organizations:

(1) An individual or type of organization or public entity that elects coverage pursuant to any provision of this division.

(2) A joint venture, partnership, association, trust, estate, joint stock company, insurance company, corporation whether domestic or foreign, limited liability company, whether domestic or foreign, community chest, fund, or foundation.

(3) A public entity. As used in this section, “public entity” means the State of California (including the Trustees of the California State University), an instrumentality of this state (including the Regents of the University of California), a political subdivision of this state or any of its instrumentalities, a county, city, district (including the governing board of a school district or community college district, a county board of education, a county superintendent of schools, or a personnel commission of a school district or community college district that has a merit system pursuant to the Education Code), entities receiving state money to conduct county fairs and agricultural fairs pursuant to Sections 25905 and 25906 of the Government Code and that perform no other functions, a public authority, public agency, or public corporation of this state, an instrumentality of more than one of the foregoing, and an instrumentality of any of the foregoing and one or more other states or political subdivisions.

(4) An instrumentality of the United States required to make payments under this division.

(5) The receiver, trustee in bankruptcy, trustee or successor thereof, and the legal representative of a deceased person.

(6) An Indian tribe as described by Section 3306(u) of Title 26 of the United States Code.

(b) All individuals performing services within this state for an employing unit that maintains two or more separate establishments within this state shall be deemed to be employed by a single employing unit for all the purposes of this division. This subdivision does not apply to an Indian tribe (as described by Section 3306(u) of Title 26 of the United States Code) and the subdivisions, subsidiaries, or other business enterprises wholly owned by the Indian tribe if the tribe chooses to treat those subdivisions, subsidiaries, or other business enterprises as separate business entities for the purposes of Section 803.