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NorthWestern Energy rate increase

Electric & gas · Montana, South Dakota · Investor-owned utility · part of NorthWestern Energy Group, Inc.

In effect

Last checked

In Montana, the latest approved rate change for NorthWestern Energy took effect February 1, 2026: Montana electric rate review (final rates February 2026), which lowered a typical 750 kWh monthly bill by about $2.16.

Details and sources · Estimate for your home

Rate changes, newest first

Montana electric rate review (final rates February 2026)

Base rate case · Montana · Electric

In effect

Typical residential bill (750 kWh/month)

  • −$2.16/mostarting February 1, 2026 (−1.83%)Final rates vs. a typical bill at January 2026 rates, which already included settlement rates in place since mid-2025. NorthWestern puts the change since July 2024 at +$5.89 (5.35%).
Filed
July 2024
Decided
December 24, 2025
Effective
February 1, 2026
Requested increase
$156.5 million
Approved increase
$105.5 million
Docket
2024.05.053

NorthWestern sought $156.5 million more in Montana electric base revenue, offset by a lower power-cost base. The PSC's Dec. 24, 2025 order allowed $105.5 million in base rates ($9.2 million net), cut about $42 million from the Yellowstone County plant's rate base and suspended power-cost sharing. Final rates began Feb. 1, 2026; NorthWestern has asked the PSC to reconsider the plant ruling.

Utility's stated reasons

  • Yellowstone County Generating Station gas plant
  • Lower power-cost (PCCAM) base offsets most of the increase
  • Wildfire mitigation and insurance cost balancing account
Sources (4) · Verified against regulator or utility filings

Last verified Oct 12, 2026

Montana natural gas rate review (final rates February 2026)

Base rate case · Montana · Natural gas

In effect

Typical residential bill (65 therms/month)

  • +$1.62/mostarting February 1, 2026 (+2.92%)Final rates vs. a typical bill at January 2026 rates. NorthWestern puts the change since July 2024 at +$5.22 (10.06%).
Filed
July 2024
Decided
December 24, 2025
Effective
February 1, 2026
Requested increase
$28.63 million
Approved increase
$18 million
Docket
2024.05.053

NorthWestern sought $28.6 million more in Montana natural gas base revenue. The PSC's Dec. 24, 2025 order approved a settlement with the Montana Consumer Counsel and others for $18.0 million in base rates. NorthWestern says a home using 65 therms a month pays $1.62 more than at January 2026 rates, and $5.22 more than in July 2024.

Utility's stated reasons

  • Gas system investments since the last rate case
  • 9.60% return on equity under the approved settlement
Sources (3) · Verified against regulator or utility filings

Last verified Oct 12, 2026

South Dakota natural gas rate increase (settlement)

Base rate case · South Dakota · Natural gas

In effect

Typical residential bill (100 therms/month)

  • +$6.47/mostarting December 19, 2024 (+6.1%)Settlement rates; residential customer charge rises from $8 to $10.

Typical bill before the change: $106.58/month

Filed
June 21, 2024
Decided
December 17, 2024
Effective
December 19, 2024
Requested increase
$6 million
Approved increase
$4.6 million
Docket
NG24-005

NorthWestern asked for about $6.0 million (9.1% of bills) in South Dakota gas revenue. The PUC approved a settlement with its staff on Dec. 17, 2024 for $4.6 million (7.0%), adding about $6.47 a month for a home using 100 therms. Rates took effect Dec. 19, 2024, and no new base increase can take effect before Jan. 1, 2028.

Utility's stated reasons

  • First South Dakota gas base rate increase since 2011
  • $82.1 million invested in the gas system since then
Sources (3) · Verified against regulator or utility filings

Last verified Oct 12, 2026

What it could mean for your bill

Sources state the impact for one typical home. Enter your own usage or bill for a rough estimate.

For: Montana electric rate review (final rates February 2026) (in effect)

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Who decides

Utility website: www.northwesternenergy.com

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Last checked Oct 12, 2026. Spotted something out of date? Tell us.