OLYMPIA, Wash.—A referendum that would allow private workers compensation insurers to compete in Washington state has been certified to appear on the November ballot, according to the Secretary of State's office.

Employers in the state that do not self-insure their workers comp coverage now can purchase insurance only from the State Fund administered by the state's Department of Labor & Industries.

The Secretary of State's office certified Initiative 1082 on Tuesday after election officials reviewed about 3% of the 345,000 signatures supporters submitted to put the issue on the ballot. About 241,000 signatures were required.