Idaho Code § 50-2518
Upon completion of the extension or conversion contemplated by this chapter, the public utility shall present the governing body with its verified bill for extension or conversion costs as computed pursuant to section 50-2515, Idaho Code, but based upon the actual cost of construction rather than the estimated cost of the facility. In no event shall the bill for extension or conversion costs presented by the public utility exceed the amount of estimated extension or conversion costs by the public utility. In the event the extension or conversion costs are less than the estimated extension or conversion costs, each owner within the improvement district shall receive the benefit, prorated in such form and at such times as the governing body may determine. The bill of the public utility corporation shall be paid within thirty (30) days by the governing body from the improvement district funds or such other source as is properly designated by the governing body. In determining the actual cost of constructing the facility the public utility shall use its standard accounting procedures, such as the uniform system of accounts as defined by the state or federal regulatory commission and as is in use at the time of the extension or conversion by the public utility involved. All rules and regulations of the utility pertaining to refund provisions for line extensions will also be applicable to an improvement district.
Idaho Code § 50-2518