(1) The electing utility will make the filings required in ARM 38.5.604(b) as follows:

(a) It will prepare its cost of service filing in compliance with the minimum filing standards, as modified by the rules of this sub-chapter. In addition:

(i) The utility will reflect in its filing as its cost of equity capital the last return on equity authorized by the commission, unless the utility proceeds in accordance with ARM 38.5.609(b) .

(ii) If the utility's filing does not seek a change in rates, its filing need not comply with the provisions of ARM 38.5.103, 38.5.104, 38.5.105, 38.5.112, 38.5.176, 38.5.177 and 38.5.178.

(b) A utility which files an application to change its rates simultaneously with the submission of its cost of service filing may include in its cost of service filing a rate of return on equity other than that last authorized by the commission.

(c) If the cost of service filing establishes a revenue requirement less than that last authorized by the commission, and the utility does not request a decrease in rates to reflect such a change, the utility expressly assumes the burden of proving why its rates should not be decreased to the extent reflected in its cost of service filing.

(d) Any party, including the utility, may make application to the commission for a change in rates based upon the filing and such other facts the parties by competent evidence may establish. All applications for a change in rates will be heard in accordance with Title 69, MCA, and the Montana Administrative Procedure Act.