Any labor guild, association, or organization qualifying as an employer under this chapter and which is required to make contributions for an elective official qualifying for membership under RCW
41.40.023(11) shall make contributions as any other employer within this chapter: PROVIDED, That the department shall cause an actuarial computation to be made of all prior service liability for which contributions are required from the employer to be computed on an actual dollar basis, and if the department determines that the contributions being made therefor under this chapter are insufficient to defray any cost to the state, the department shall require additional contributions from the employer in amounts and at times as will defray all costs to the state, the additional contributions to be completed within ten years from the date the elective official is accepted by the department.