Wash. Rev. Code § 81.04.310
The commission may, both as to original and supplementary budgets, prior to the making or contracting for the expenditure of any item therein, and after notice to the company and a hearing thereon, reject any item of the budget. The commission may require any company to furnish further information, data, or detail as to any proposed item of expenditure.
Failure of the commission to object to any item of expenditure within sixty days of the filing of any original budget or within thirty days of the filing of any supplementary budget shall constitute authority to the company to proceed with the making of or contracting for such expenditure, but such authority may be terminated at any time by objection made thereto by the commission prior to the making of or contracting for such expenditure.
Examination, investigation, and determination of the budget by the commission shall not bar or estop it from later determining whether any of the expenditures made thereunder are fair, reasonable, and commensurate with the service, material, supplies, or equipment received.
RCW 81.04.310