(1) When the commission engages independent consultants or advisory services to evaluate a utility's default supply resource procurement plans and proposed power supply purchase agreements pursuant to 69-8-421 , MCA, the commission will charge the default supplier a fee commensurate with the costs of the consultant or advisory services. The default supplier, at the commission's direction, will deposit the fee into the commission's account in the special revenue fund pursuant to 69-8-421 , MCA. The initial fee charged to the default supplier will be based upon the commission's estimate of costs for the consultant or advisory services. The commission may revise the fee amount as the actual costs become known.