Cal. Unemp. Ins. Code § 632
"Employment" does not include service performed in the employ of any other state or its political subdivisions or in the employ of the United States government or of any instrumentality of the United States, but if Congress permits the states to require any instrumentalities of the United States to make payments into a fund under a state unemployment compensation act, and to comply with state regulations thereunder, then, to the extent permitted by Congress, all of the provisions of this division shall be applicable to the instrumentalities and to services performed for the instrumentalities in the same manner, to the same extent, and on the same terms as to all other employers, employing units, individuals, and services.
If this state is not certified by the Secretary of Labor under Section 3304 of the Internal Revenue Code of 1986 for any year, then the payments required of the instrumentalities and their workers with respect to the year shall be refunded from the Unemployment Fund without interest.
Ca. Unemp. Ins. Code § 632