Section 49-05-04.1 - Test year - Public utility rate filings1. A public utility, at its option, may use any one of the following twelve-month periods as its test year for rate filings with the commission: a. A historical test year, which may be either the latest twelve-month period for which actual data is available at the time of filing new schedules or the latest calendar or fiscal year for which actual data is available at the time of filing new schedules.b. A current test year, which is any consecutive twelve-month period ending not later than twelve months after the date new schedules are filed. A public utility selecting a current test year also shall file data for the twelve-month period immediately preceding the current test year selected and that period is the "historical period" for the public utility.c. A future test year, which is any consecutive twelve-month period ending no later than twenty-four months after the date new schedules are filed. A public utility selecting a future test year must file data for the twelve consecutive months immediately preceding the future test year and that period is the "current period" for the public utility.2. A public utility selecting a current or future test year shall present the following information: a. A comparison of forecast data to historical period data to demonstrate the reliability and accuracy of the utility's forecast including a comparison of the prior years' forecast or budgeted data to actual data for those periods.b. A statement that the public utility's forecast is reasonable, reliable, and was made in good faith and that all basic assumptions used in making or supporting the forecast are reasonable, evaluated, identified, and justified to allow the commission to test the appropriateness of the forecast.c. A statement that the accounting treatment that has been applied to anticipated events and transactions in the forecast is the same as the accounting treatment to be applied in recording the events once they have occurred.3. The public utility may update its filing for material changes as actual data becomes available up to thirty days before the hearing. Except for good cause shown, a public utility may not submit more than one updated filing before the hearing. In the absence of an updated filing by the public utility, the commission may require a public utility to update its filing when the commission staff introduces evidence that a material change has occurred.4. A public utility may propose estimated or calculated adjustments to the selected historical or current test year for all known and measurable changes in operating results as measured in the test year. The adjustments must be made in the same context and format as the information was provided in the original filing. The adjustments may reflect material changes in plant investment, operating revenues, expenses, and capital structure if the changes occurred during the selected historical or current test year or are reasonably certain to occur subsequent to the selected test year within twelve months from the date of the rate filing.