Wash. Rev. Code § 50.04.210
The term "employment" shall not include service performed in the employ of any other state or its political subdivisions, or of the United States government, or of any instrumentality of any other state or states or their political subdivisions, or the United States; except that if the congress of the United States shall permit states to require any instrumentality of the United States to make payments into an unemployment fund under a state unemployment compensation act, then, to the extent permitted by congress, and from and after the date when such permission becomes effective all the provisions of this title shall be applicable to such instrumentalities and to services performed for such instrumentalities in the same manner, to the same extent and on the same terms as to all other employers, employing units, individuals and services: PROVIDED, That if this state should not be certified by the social security board under section 903 of the social security act, as amended, for any year, then the payment required of such instrumentalities with respect to such year shall be deemed to be erroneously collected and shall be refunded by the commissioner from the fund in accordance with the provisions of this title relating to adjustments and refunds of contributions, interest, or penalties which have been paid.
RCW 50.04.210
Conflict with federal requirements-Effective dates-Construction-1983 1st ex.s. c 23: See notes following RCW 50.04.073.