(21) Revenue from Contracts with Customers

    Accounting Policy

Our revenues are primarily from tariff based sales. We provide gas and/or electricity to customers under these tariffs without a defined contractual term (at-will). As the revenue from these arrangements is equivalent to the electricity or gas supplied and billed in that period (including estimated billings), there will not be a shift in the timing or pattern of revenue recognition for such sales. We have also completed the evaluation of our other revenue streams, including those tied to longer term contractual commitments. These revenue streams have performance obligations that are satisfied at a point in time, and do not have a shift in the timing or pattern of revenue recognition.

Customers are billed monthly on a cycle basis. To match revenues with associated expenses, we accrue unbilled revenues for electric and natural gas services delivered to customers, but not yet billed at month-end.

Nature of Goods and Services

We currently provide retail electric and natural gas services to three primary customer classes. Our largest customer class consists of residential customers, which include single private dwellings and individual apartments. Our commercial customers consist primarily of main street businesses, and our industrial customers consist primarily of manufacturing and processing businesses that turn raw materials into products.

Electric Segment - Our regulated electric utility business primarily provides generation, transmission, and distribution services to our customers in our Montana and South Dakota jurisdictions. We recognize revenue when electricity is delivered to the customer. Payments on our tariff based sales are generally due in 20-30 days after the billing date.

Natural Gas Segment - Our regulated natural gas utility business primarily provides production, storage, transmission, and distribution services to our customers in our Montana, South Dakota, and Nebraska jurisdictions. We recognize revenue when natural gas is delivered to the customer. Payments on our tariff based sales are generally due in 20-30 days after the billing date.

Disaggregation of Revenue

The following tables disaggregate our revenue for the twelve months ended by major source and customer class (in thousands):
December 31, 2025ElectricNatural GasTotal
Montana406,643 120,830 527,473 
South Dakota77,894 28,948 106,842 
Nebraska— 25,733 25,733 
Residential484,537 175,511 660,048 
Montana408,530 68,722 477,252 
South Dakota120,108 21,574 141,682 
Nebraska— 13,784 13,784 
Commercial528,638 104,080 632,718 
Industrial43,128 2,439 45,567 
Lighting, governmental, irrigation, and interdepartmental34,510 1,350 35,860 
Total Retail Revenues1,090,813 283,380 1,374,193 
Regulatory Amortization58,265 (305)57,960 
Transmission111,024 — 111,024 
Transportation, wholesale and other9,854 57,528 67,382 
Total Revenues $1,269,956 $340,603 $1,610,559 
December 31, 2024ElectricNatural GasTotal
Montana398,790 110,215 509,005 
South Dakota70,012 26,884 96,896 
Nebraska— 21,205 21,205 
Residential468,802 158,304 627,106 
Montana408,977 59,925 468,902 
South Dakota111,813 18,069 129,882 
Nebraska— 11,432 11,432 
Commercial520,790 89,426 610,216 
Industrial46,637 1,041 47,678 
Lighting, governmental, irrigation, and interdepartmental32,811 1,352 34,163 
Total Retail Revenues1,069,040 250,123 1,319,163 
Regulatory Amortization24,908 19,017 43,925 
Transmission97,052 — 97,052 
Transportation, wholesale and other9,701 44,057 53,758 
Total Revenues$1,200,701 $313,197 $1,513,898 

December 31, 2023ElectricNatural GasTotal
Montana408,341 136,097 544,438 
South Dakota67,888 36,638 104,526 
Nebraska— 35,539 35,539 
Residential476,229 208,274 684,503 
Montana431,357 73,721 505,078 
South Dakota103,194 25,869 129,063 
Nebraska— 22,114 22,114 
Commercial534,551 121,704 656,255 
Industrial45,958 1,392 47,350 
Lighting, governmental, irrigation, and interdepartmental32,756 1,681 34,437 
Total Retail Revenues1,089,494 333,051 1,422,545 
Regulatory Amortization(105,608)(25,012)(130,620)
Transmission78,436 — 78,436 
Transportation, wholesale and other6,511 45,271 51,782 
Total Revenues$1,068,833 $353,310 $1,422,143 

Historical Timeline

Fiscal YearFiled
2025Feb 12, 2026Showing above
2024Feb 13, 2025
2023Feb 15, 2024

About Revenue Disclosures

Revenue disclosures under ASC 606 explain how a company identifies performance obligations, allocates transaction prices, and determines when revenue is recognized. This section is essential for understanding whether reported revenue reflects genuine economic activity or aggressive accounting choices. Analysts examine the mix of point-in-time versus over-time recognition, which directly affects revenue timing and comparability.

Key signals: rising contract liabilities (deferred revenue) suggest strong future revenue visibility, while declining contract assets may indicate slowing project milestones. Watch for variable consideration estimates — rebates, returns, and performance bonuses that require management judgment. Significant changes in disaggregated revenue by geography or product line can reveal shifting business mix before it appears in headline numbers. Compare revenue growth against contract liability growth to assess sustainability, and scrutinize any changes in the timing of recognition that coincide with earnings pressure.