20260731Brandon Workpaper.pdf

RECEIVED
JULY 31, 2026
IDAHO PUBLIC
UTILITIES COMMISSION
CASE NO. AVU-E-26-05
2026 Idaho PCA Filing
Brandon Workpapers
Brandon, Di 2
Avista Corporation

Exhibit AMB-1
AVISTA UTILITIES
IDAHO ELECTRIC
IMPACT OF PROPOSED SCHEDULE 66 PCA CHANGE
PROPOSED RATE TO BE EFFECTIVE OCTOBER 1,2026
(000s of Dollars)
(000s of kWh) Total Billed Percent
Revenue Proposed change
Line Type of Schedule Forecasted at Present Sch.66 on Billed
No. Service Number Kilowatt-hours Rates Change Revenue
(a) (b) (c)(1) (d) (e) (f)
1 Residential 1 1,357,313 $ 174,917 $ 6,216 3.6%
2 General Service 11,12 962,222 $ 103,092 $ 4,407 4.3%
3 Large General Service 21,22 95,546 $ 11,156 $ 438 3.9%
4 Extra Large General Service 25 348,913 $ 24,076 $ 1,598 6.6%
5 Clearwater 25P 342,572 $ 19,825 $ 1,569 7.9%
6 Pumping Service 31,32 65,718 $ 8,697 $ 301 3.5%
7 Street&Area Lights 42-49 9,377 $ 4,271 $ 43 1.0%
8 Total 3,181,661 $ 346,034 $ 14,572 4.2%
check 4.2%
9 Proposed rate $ 0.00157 $ 5,001
10 Present rate(AVU-E-24-07,Order No.36339) $ (0.00301) $ (9,576)
11 Rate Change $ 0.00458 $ 14,577
Proposed rate
12 Total Amortization and Deferral Balance including interest thru 9/30/26 $ 4,979
13 Conversion factor(Case No.AVU-E-25-01: Per Final Stipulation&Settlement) 0.995661
14 Revenue Requirement 5,001
15 kWh's from above 3,181,661
16 Proposed rate: $ 0.00157
(1) Source: Calendar Load forecast for the twelve month period October 1,2025-September 30,2026
Exhibit AMB-1
Page 1 of 10

Avista Corporation PCA -1 1000
July 2025 through June 2026
IPUC Deferral Analysis
AVU-E-23-01 AVU-E-25-01 Jul-25 thru
Deferral for 2025-26 Deferral Period JulJul 25 Aug-25 Sep-25 OCt-25 Nov-25 Dec-25 Jan 26 Feb-26 Mar-26 Apr-26 May-26 Jun-26 Jun-26
BASE RATE RECOVERY-LOAD CHANGE ADJUSTMENT
Idaho Actual Sales MWh 280,828 267,655 239,609 234,706 258,809 283,578 305,816 251,543 267,885 230,607 219,525 224,518 3,065,079
Idaho Base Sales MWh 256,211 254,893 215,718 232,623 269,741 307,917 326,882 281,061 274,963 240,388 233,037 224,084 3,117,518
Actual-Base Sales MWh 24,617 12,762 23,891 2,083 (10,932) (24,339) (21,066) (29,518) (7,078) (9,781) (13,512) 434 (52,439)
LCAR $/MWh 24.50 24.50 23.67 23.67 23.67 23.67 23.67 23.67 23.67 23.67 23.67 23.67
Retail Revenue Adjustment-Under(+)/Over(-) (603,117) (312,669) (565,500) (49,305) 258,760 576,104 498,632 698,691 167,536 231,516 319,829 (10,273) 1,210,204
Base-to-Actual Percent Difference % 9.61% 5.01% 11.08% 0.90% -4.05% -7.90% -6.44% -10.50% -2.57% 4.07% -5.80% 0.19% -1.68%
NET POWER SUPPLY EXPENSE
Actual Expense
555 Purchased Power $ 19,209,958 16,654,111 18,286,103 17,846,771 17,354,801 16,893,835 15,751,318 15,297,837 17,568,185 18,719,098 19,306,960 19,298,939 212,187,916
447 Sales for Resale $ (17,937,409) (12,794,325) (15,668,130) (17,375,777) (14,138,414) (12,674,552) (7,968,949) (7,919,128) (8,396,819) (11,955,861) (12,043,988) (14,703,882) (153,577,134)
501 Thermal Fuel $ 4,607,181 4,605,093 3,277,731 4,711,461 3,628,545 2,650,451 1,004,603 778,295 345,779 118,600 2,012 (1,476) 25,728,275
547 CT Fuel $ 7,792,958 8,932,539 8,529,664 9,694,204 10,315,919 10,281,031 10,616,482 9,507,402 4,812,672 2,419,465 1,931,468 3,777,507 88,601,311
456 Transmission Revenue $ (2,610,094) (2,403,819) (2,471,210) (2,810,887) (2,591,546) (2,667,143) (2,964,607) (2,838,708) (2,989,694) (3,012,020) (3,076,025) (2,955,015) (33,390,758)
565 Transmission Expense $ 2,489,270 2,498,218 2,431,566 2,855,265 2,790,518 2,748,185 2,668,585 2,695,391 2,763,490 2,739,038 2,633,762 2,685,077 31,998,365
537 MT.Invasive Species Expense $ 64,722 64,722 64,722 64,722 64,722 64,722 64,722 64,722 64,722 64,722 64,722 64,722 776,664
557 Expense Broker Fees $ 2,102 1,853 2,658 2,916 (19,418) 376 504 1,457 2,980 19,142 14,990 20,144 49,704
557 Resource Optimization $ (833,877) 231,742 (244,294) (1,068) (103,028) (33,792) 3,543,128 396,268 1,428,490 453,999 474,781 227,529 5,539,878
Adjusted Actual Net Expense $ 12,784,811 17,790,134 14,208,810 14,977,607 17,302,099 17,263,113 22,715,886 17,983,536 15,599,815 9,566,183 9,308,682 8,413,545 177,914,221
Idaho Allocation Factor $ 34.47% 34.47% 35.52% 35.52% 35.52% 35.52% 35.52% 35.52% 35.52% 35.52% 35.52% 35.52%
Idaho Actual Net Expense $ 4,406,924 6,132,259 5,046,969 5,320,046 6,145,706 6,131,859 8,068,683 6,387,752 5,541,054 3,397,908 3,306,445 2,988,491 62,874,096
Authorized Net Expense
555 Purchased Power $ 5,937,659 5,836,088 12,753,120 13,316,871 11,607,682 12,096,106 22,800,890 14,553,299 14,292,153 16,075,993 16,801,795 16,631,043 162,702,699
447 Sales for Resale $ (9,557,120) (4,493,194) (19,953,584) (15,137,594) (18,382,654) (26,178,834) (1,416,534) (13,038,624) (9,709,334) (11,804,984) (14,837,724) (17,413,234) (161,923,414)
501 Thermal Fuel $ 2,879,162 3,146,005 3,968,536 3,155,810 3,272,978 3,539,225 679,663 922,483 869,703 433,873 101,373 330,873 23,299,684
547 CT Fuel $ 6,693,265 7,977,571 8,781,685 7,732,236 10,506,214 13,732,592 8,712,646 11,748,648 9,927,317 5,970,843 4,074,001 4,753,424 100,610,442
456 Transmission Revenue $ (2,267,860) (2,209,469) (3,099,146) (3,125,305) (2,986,534) (3,189,458) (3,183,581) (3,191,635) (3,172,317) (3,771,567) (2,633,999) (2,846,226) (35,677,097)
565 Transmission Expense $ 1,439,897 1,439,897 2,743,528 2,743,528 2,743,528 2,743,528 2,743,528 2,743,528 2,743,528 2,743,528 2,743,528 2,743,528 30,315,074
90%Palouse Wind and Rattlesnake Flats $ 2,442,750 2,442,750 0 0 0 - 0 0 0 0 0 0 4,885,500
Remove Columbia Basin Hydro Transmission Project(embedd $ (83,917) (83,917) 0 0 0 - 0 0 0 0 0 0 (167,834)
Gas Liquids Revenue-456018 $ (524,310) (514,471) 1,337,159 1,088,750 1,265,257 2,162,511 3,582,523 1,723,440 1,121,053 589,881 1,040,209 994,579 13,866,581
Montana Invasive Species Expense $ 134,167 134,167 65,000 65,000 65,000 65,000 65,000 65,000 65,000 65,000 65,000 65,000 918,334
Shaping Adjustment $ 0 0 3,839,288 4,121,443 5,998,200 9,178,058 79,872 79,872 79,872 79,872 79,872 79,872
Settlement Adjustments $ 52,636 52,636 79,872 79,872 79,872 79,872 (4,507,858) 60,685 (3,879,221) 10,013 (1,645,892) 290,881 9,246,632
Authorized Net Expense $ 7,146,329 13,728,063 10,515,458 14,040,611 14,169,543 14,228,600 29,556,149 15,666,696 12,337,754 10,392,452 5,788,163 5,629,740 153,199,558
Idaho Allocation Factor $ 34.47% 34.47% 35.52% 35.52% 35.52% 35.52% 35.52% 35.52% 35.52% 35.52% 35.52% 35.52%
Idaho Authorized Net Expense $ 2,463,340 4,732,063 3,735,091 4,987,225 5,033,022 5,053,999 10,498,344 5,564,810 4,382,370 3,691,399 2,055,955 1,999,684 54,197,302
RENEWABLE ENERGY CREDIT REVENUE
Actual REC Revenue $ 0 0 0 0 0 0
Authorized REC Revenue $ 0 0 0 0 0 0 0
Actual-Authorized REC Revenue $ 0 0 0 0 0 0 0 0 0 0 0 0 0
Idaho Allocation Factor $ 34.47% 34.47% 34.52% 34.52% 34.52% 34.52% 34.52% 34.52% 34.52% 34.52% 34.52% 34.52%
Actual-Authorized Idaho REC Revenue $ 0 0 0 0 0 0 0 0 0 0 0 0 0
COST RECOVERY SUBJECT TO SHARING
Actual-Authorized Net Expense(Idaho share) $ 1,943,594 1,400,196 1,311,878 332,821 1,112,684 1,077,860 (2,429,661) 822,942 1,158,694 (293,491) 1,250,490 988,807 8,676,794
Retail Revenue Adjustment $ (603,117) (312,669) (565,500) (49,305) 258,760 576,104 498,632 698,691 167,536 231,516 319,829 (10,273) 1,210,204
REC Revenue $ 0 0 0 0 0 0 0 0 0 0 0 - 0
456030 ED ID-Sch 25P Transmission $ 14,850 14,850 14,850 14,850 14,850 14,850 14,850 15,154 15,400 15,400 15,400 15,400 180,704
456380 ED ID-Sch 25P REC Revenue $ (96,622) (100,273) (64,606) (92,533) (99,904) (97,419) (106,004) (102,251) (88,636) (89,660) (99,555) (105,078) 1,142,541)
Sch 25P Net Cost (81,772) (85,423) (49,756) (77,683) (85,054) (82,569) (91,154) (87,097) (73,236) (74,260) (84,155) (89,678) (961,837)
Total Cost(Subject to Sharing) $ 1,258,695 1,002,104 696,622 205,833 1,286,390 1,571,395 (2,022,183) 1,434,536 1,252,994 (136,235) 1,486,164 888,856 8,925,161
Sharing Percentage % 90% 90% 90% 90% 90% 90% 90% 90% 90% 90% 90% 90%
Total Cost Recovery Subject to Sharing $ 1,132,827 901,894 626,960 185,250 1,157,751 1,414,256 (1,819,965) 1,291,083 1,127,686 (122,612) 1,337,548 799,970 8,032,648
Energy Imbalance Market Incremental O&M Costs RI $ 34,606 45,542 (14,209) 16,801 16,801 16,801 16,345 14,472 18,442 17,134 16,685 16,685 216,105
Sharing Percentage % 90% 90% 90% 90% 90% 90% 90% 90% 90% 90% 90% 90% 90%
EIM O&M Costs Subject to Sharing 31,145 40,988 (12,788) 15,121 15,121 15,121 14,711 13,025 16,598 15,421 15,017 15,017 194,495
Total Power Cost Deferral with Adjustments(Balance Sheet $ 1,163,972 942,882 614,172 200,371 1,172,872 1,429,377 (1,805,254) 1,304,108 1,144,284 (107,191) 1,352,565 814,987 8,227,143
Monthly Interest Rate % 0.41667% 0.41667% 0.41667% 0.41667% 0.41667% 0.41667% 0.33333% 0.33333% 0.33333% 0.33333% 0.33333% 0.33333% 0.33333% 0.33333% 0.33333%
PCA Ending Balances
AVU-E-26-05 2026 Brandon Workpapers
Act-Auth-Proposed Page 2 of 10

Avista Corporation PCA -1 1000
July 2025 through June 2026
IPUC Deferral Analysis
AVU-E-23-01 AVU-E-25-01 Jul-25 thru
Deferral for 2025-26 Deferral Period JulJul 25 Aug-25 52p-25 OCt-25 N0v-25 Dec-25 JanJan 26 Feb-26 Mar-26 Apr-2 6 May-26 lun-26 Jun-26
Account 182385 June 2025 Ending Balance $ (7,913,979)
Account 182386 June 2025 Ending Balance $
Account 182387 June 20245Ending Balance $ (3,388,458)
2023-2024 Beginning Balance $ (11,302,437) (12,271,726) (10,721,989) (9,506,721) (8,749,812) (6,927,702) (4,647,843) (5,599,945) (3,507,902) (1,522,762) (885,525) 1,106,605 2,614,220 3,337,148 4,167,931
Current Year Deferral-Account 182385 $ 1,163,972 942,882 614,172 200,371 1,172,872 1,429,377 (1,805,254) 1,304,108 1,144,294 (107,191) 1,352,565 814,987
RPS Compliance Adjustment $ (2,717,969)
Amortization-Account 182386 $
Amortization-Account 182387 $ 631,802 657,988 645,771 596,150 685,697 879,347 868,644 806,603 852,550 749,504 642,519 688,938
Amortization-Projected $ 714,214 819,659 797,493
Ending Balance w/out Current Month Interest $ (12,224,632) (10,670,856) (9,462,046) (8,710,200) (6,891,243) (4,618,978) (5,584,453) (3,489,234) (1,511,068) (880,449) 1,109,559 2,610,530 3,328,434 4,156,807 4,965,424
Interest $ (47,094) (51,133) (44,675) (39,612) (36,458) (28,866) (15,494) (18,667) (11,692) (5,074) (2,952) 3,689 8,714 11,124 13,893
2024-25 Final Ending Deferral Balance $ (12,271,726) (10,721,989) (9,506,721) (8,749,812) (6,927,702) (4,647,846) (5,599,945) (3,507,902) (1,522,762) (885,525) 1,106,605 2,614,220 3,337,148 4,167,931 4,979,317
"'Per Avista ID General Rate Case,Case No.AVU-E-21-01,Order No.35156,section 6.Other Settlement Components,subpart E.Energy Imbalance Market("EIM")
AVU-E-26-05 2026 Brandon Workpapers
Act-Auth-Proposed Page 3 of 10

Source:EREV April Mid-month 04.13.26,Bill Determ Tab
Calendar Load(kWh)by Rate Schedule
Oct 26 Nov 26 Dec 26 Jan 27 Feb 27 Mar 27 Apr 27 May 27 Jun 27 Jul 27 Aug 27 Sep 27 Total
0001 86,333,299 121,863,301 160,465,667 154,930,089 139,156,810 118,666,137 106,894,503 88,516,839 89,052,164 105,999,937 101,703,594 83,730,499 1,357,312,839
IDO11 73,244,045 78,779,459 82,138,227 84,819,055 81,192,446 74,170,787 72,211,646 68,496,334 74,117,543 81,275,711 78,820,282 70,389,421 919,654,956
ID012 2,743,413 3,842,873 5,142,397 5,133,273 4,812,580 4,077,985 3,391,837 2,607,116 2,586,885 2,905,616 2,761,851 2,561,324 42,567,150
ID021 7,207,343 7,740,930 7,718,772 8,031,806 7,747,309 7,135,223 7,276,956 6,785,064 7,145,363 7,537,428 7,092,843 6,502,466 87,921,503
ID022 574,209 623,428 769,243 809,027 809,148 652,699 568,023 524,835 536,646 591,135 610,486 555,971 7,624,850
ID025 31,351,852 26,895,502 29,005,877 31,310,328 26,457,045 31,349,446 28,158,204 28,924,560 27,612,320 29,190,202 31,144,501 27,512,720 348,912,557
ID025P 27,586,973 23,306,893 29,583,770 27,834,871 23,821,764 31,564,328 25,369,988 31,866,117 27,446,117 33,325,711 31,991,481 28,873,906 342,571,919
ID031 5,149,351 2,146,705 3,222,878 3,434,549 3,451,560 3,293,806 3,264,730 4,993,324 7,508,184 8,550,900 9,190,864 6,742,082 60,948,933
ID032 234,350 213,152 259,436 288,387 254,715 224,774 210,983 297,976 517,341 910,553 899,023 458,311 4,769,001
I D04X 773,571 766,192 802,861 788,703 769,481 781,064 791,694 772,986 782,670 782,581 778,027 787,252 9,377,082
Total 235,198,406 266,178,435 319,109,128 317,380,088 288,472,858 271,916,249 248,138,564 233,785,151 237,305,233 271,069,774 264,992,952 228,113,952 3,181,660,790
- check
Calendar Loads
Mar-26 Apr-26 May-26 Jun-26 Jul-26 Aug-26 Sep-26
I13001 112,849,283 104,376,798 86,503,174 90,066,432 107,774,596 101,864,705 85,809,518
IDO11 72,235,929 68,928,106 68,819,611 73,746,161 81,003,883 79,305,099 70,381,368
ID012 3,892,269 3,188,362 2,501,563 2,522,296 2,802,479 2,682,104 2,520,664
ID021 7,791,918 7,214,794 6,825,049 7,121,093 7,526,086 7,149,781 6,507,291
ID022 645,431 549,751 520,800 527,005 588,393 607,828 559,874
ID025 31,708,131 28,832,699 28,840,003 27,649,103 29,508,874 30,992,249 27,695,867
ID025P 29,037,823 24,868,787 29,693,285 26,571,065 32,638,981 31,487,230 27,399,867
ID031 3,139,239 3,029,778 5,139,292 7,769,354 8,771,531 9,173,757 7,147,553
ID032 205,913 209,271 300,136 517,744 906,924 899,639 460,413
IDDU 799,065 795,037 786,018 790,149 790,339 785,301 792,118
Total 262,305,001 241,993,383 229,928,931 237,280,402 272,312,086 264,947,693 229,274,533 1,738,042,029
Present Rate -$0.00301 -$0.00301 -$0.00301 -$0.00301 -$0.00301 -$0.00301 -$0.00301
-$789,538 -$728,400 -$692,086 -$714,214 -$819,659 -$797,493 -$690,116
Present RCF' 0.995661 0.995661 0.995661 0.995661 0.995661 0.995661 0.995661
-$786,112 -$725,239 -$689,083 -$711,115 -$816,302 -$794,033 -$687,122 -$2,297,257
`Case No.AVU-E-25-01:Per Final Stipulation&Settlement
AVU-E-26-05 2026 Brandon
Workpapers KWh Forecast and Rev Page 4 of 10

AVISTA UTILITIES
Settlement Revenue Conversion Factor
Idaho - Electric System
TWELVE MONTHS ENDED JUNE 30, 2024
Line
No. Description Factor
1 Revenues 1.000000
Expenses:
2 Uncollectibles 0.002212
3 Commission Fees 0.002127
4 Idaho Income Tax
5 Total Expenses 0.004339
6 Net Operating Income Before FIT 0.995661
Case No.AVU-E-25-01: 2025 Id Electric RR Model 06.2024 Settlement-Sent to Staff
(this is same as last year;two year rate plan)
AVU-E-26-05 2026 Brandon Workpapers
Conversion Factor Page 5 of 10

Bill Determinants
2026 Idaho Annual PCA Filing
Present Proposed
Basic Charge $ 20.00 $ 20.00
Block 1 $ 0.10065 $ 0.10523
Block 2 $ 0.11287 $ 0.11745
Tax Rate 0.000923 0.000923
Present Proposed
Bill Bill
Basic Charge $ 20.00 $ 20.00
Block 1 $ 60.39 $ 63.14 600
Block 2 $ 38.26 $ 39.82 339
Tax Rate $ 0.87 $ 0.87
Total Bill $ 119.52 $ 123.83 939
Total Bill Impact $ 4.31 3.6%
AVU-E-26-05 2026 Brandon Workpapers
Bill Impact Page 6 of 10

Avista Utilities
Idaho Jurisdiction
2026 PCA
Electric Service
(000s of Dollars)
(000s of kWh)
PCA Present Present Proposed Proposed Proposed Incremental
Type of Schedule Billing PCA PCA PCA PCA PCA Rate
Service Number Determinants Rate Revenue Decrease Revenue Rate change
(a) (b) (c) (d) (e) (f) (g) (h) (i)
Residential 1 1,357,313 $ (0.00301) $ (4,086) $ 6,217 $ 2,131 $ 0.00157 $ 0.00458
General Service 11/12 962,222 $ (0.00301) $ (2,896) $ 4,407 $ 1,511 $ 0.00157 $ 0.00458
Large General Service 21/22 95,546 $ (0.00301) $ (288) $ 438 $ 150 $ 0.00157 $ 0.00458
Extra Large General Service 25 348,913 $ (0.00301) $ (1,050) $ 1,598 $ 548 $ 0.00157 $ 0.00458
Clearwater 25P 342,572 $ (0.00301) $ (1,031) $ 1,569 $ 538 $ 0.00157 $ 0.00458
Pumping Service 31/32 65,718 $ (0.00301) $ (198) $ 301 $ 103 $ 0.00157 $ 0.00458
Street&Area Lights 41-49 9,377 $ (0.00301) $ (28) $ 43 $ 15 $ 0.00157 $ 0.00458
Total 3,181,661 $ (9,577) $ 14,573 $ 4,996
AVU-E-26-05 2026 Brandon Workpapers
Bill Impact for Staff Page 7 of 10

Schedule Percent change
Type of Service Number on Billed Revenue
Residential 1 3.6%
General Service 11,12 4.3%
Large General Service 21,22 3.9%
Extra Large General Service 25 6.6%
Clearwater 25P 7.9%
Pumping Service 31,32 3.5%
Street&Area Lights 41-49 1.0%
Total 4.2%
AVU-E-26-05 2026 Brandon Workpapers
Tables Page 10 of 10