(1) Commission basis reports are due within four months of the end of a utility's fiscal year.

(2) The intent of the commission basis report is to depict the electric operations of an electric utility under normal temperature and power supply conditions during the reporting period. The commission basis report must include:

(a) Booked results of electric operations and rate base, and all the necessary adjustments as accepted by the commission in the utility's most recent general rate case or subsequent orders;

(b) Results of operations adjusted for any material out-of-period, nonoperating, nonrecurring, and extraordinary items or any other item that materially distorts reporting period earnings and rate base; and

(c) Booked revenues and power supply expenses adjusted to reflect operations under normal temperature and power supply conditions before the achieved return on rate base is calculated.

(3) Commission basis reports should not include adjustments that annualize price, wage, or other cost changes during a reporting period, nor new theories or approaches that have not been previously addressed and resolved by the commission.

(4) Each utility must submit the basis of any cost allocations and the allocation factors necessary to develop the commission basis results of electric operations for the state of Washington.