The County Executive is authorized to negotiate and enter into multi-year contracts with the Washington State Department of Revenue for the purpose of collecting taxes imposed under this Chapter, as well as for the purpose of providing system services, as authorized by RCW 82.14B.063. The County Executive shall provide the Department of Revenue notice of the imposition of tax or of a change in the tax imposed by this Chapter no less than 75 days before the effective date of the imposition of the tax or of a change in the tax.