Avista Makes Annual Price Adjustment Filings in Idaho

Avista has made annual filings with the Idaho Public Utilities Commission (IPUC or Commission) that have no impact on Avista’s earnings. These filings seek to true-up the level of costs in customer rates with the actual level incurred by the Company.

The Company filed three annual natural gas requests that, if approved, would update natural gas rates starting November 1, 2026 as shown below: Purchased Gas Cost Adjustment (PGA): a decrease of approximately $2.5 million or 3.0% Fixed Cost Adjustment (FCA): an increase of approximately $2.4 million or 2.8% Natural Gas Energy Efficiency Adjustment: a decrease of approximately $1.4 million or 1.6%

The Company filed three annual electric requests that, if approved, would update electric rates starting November 1, 2026 as shown below: Power Cost Adjustment (PCA): an increase of approximately $14.6 million or 4.2% Fixed Cost Adjustment (FCA): an increase of approximately $4.0 million or 1.2% Bonneville Power Administration Residential Exchange (ResEx) Program: a decrease of approximately $0.3 million or 0.1%

If the natural gas PGA, Energy Efficiency and FCA filings are approved, residential natural gas customers in Idaho using an average of 66 therms per month would see their monthly bills decrease from $59.28 to $58.38, a decrease of $0.90 per month, or approximately 1.5%. The proposed natural gas rate change would be effective Nov. 1, 2026. The net effect, on a revenue basis, for the requested natural gas rate change by rate schedule are as follows: General Service - Schedule 101 -1.5% Large General Service - Schedules 111 & 112 -3.1% Interruptible Service - Schedules 131 & 132 0.0% Transportation Service - Schedule 146 0.0% Overall -1.8%

If the electric PCA, FCA and ResEx filings are approved, residential electric customers in Idaho using an average of 939 kilowatt hours per month would see their monthly bills increase from $119.52 to $127.28, an increase of $7.76 per month, or approximately 6.5%. The proposed electric rate change would be effective Oct. 1, 2026. The net effect, on an annual revenue basis, for the requested electric rate changes by rate schedule are as follows: Residential Service - Schedule 1 6.4% General Service - Schedules 11 & 12 3.2% Large General Service - Schedules 21 & 22 2.9% Extra Large General Service - Schedule 25 6.6% Extra Large General Service - Schedule 25P 7.9% Pumping Service - Schedules 31 & 32 2.6% Street & Area Lights - Schedules 42-49 1.0% Overall 5.3%

PGA requests are typically filed annually to balance the actual cost of wholesale natural gas purchased by Avista to serve customers with the amount presently included in customer rates. Avista does not make a profit on, or markup, the wholesale cost of natural gas. PGAs ensure customers pay what Avista pays, dollar for dollar, only at a more predictable and stable rate throughout the year. These rate adjustments are driven primarily by lower wholesale natural gas prices observed during this past winter, which were below the amounts included in rates. Fixed Cost Adjustment (FCA) The electric and natural gas FCA is a mechanism designed to break the link between a utility’s revenues and customers’ energy usage. Avista’s actual revenue, based on kilowatt hour or therm sales, will vary, up or down, from the level included in a general rate case and approved by the Commission. This could be caused by changes in weather, energy conservation or other factors. Under the FCA, Avista’s reve