NorthWestern Corporation, a regulated energy service company operating in Montana and a subsidiary of NorthWestern Energy Group, Inc., doing business as NorthWestern Energy (NASDAQ:NWE), filed an application with the Montana Public Service Commission requesting approval of a Large New Load Tariff rule to establish requirements and contract terms for providing electric service to bundled customers with new or expanded loads of 5 megawatts or greater, including data centers and other energy‑intensive operations.

The filing establishes a framework governing agreements between NorthWestern Energy and large new load customers and is intended to address the costs and operational considerations associated with serving those loads while protecting existing customers from cost shifting and other adverse impacts.

"Our responsibility is to serve new opportunities in a way that protects our existing customers and strengthens Montana's energy future," said NorthWestern Energy President and CEO Brian Bird. "This proposal reflects Montana values—fairness, accountability, and thoughtful growth—while positioning our state to compete for high‑quality economic development."

NorthWestern Energy's filing of this proposed tariff provides a forum for the Montana Public Service Commission and interested stakeholders to evaluate NorthWestern Energy's plans to serve new large loads.

"Given the strong interest from both the Montana Public Service Commission and the public, we believe it is important to bring this issue forward now, instead of waiting until a contract with a large new load customer is in place," Bird said. "Filing this tariff now supports constructive dialogue as we all work together toward a solution that serves Montana best."

NorthWestern Energy continues to negotiate agreements with prospective large new load customers.

Customer Protections and Contract Requirements

The Large New Load Tariff includes specific requirements that must be incorporated into electric service agreements with large new load customers. These provisions include:

Minimum service commitment periods, including longer minimum terms for customers with very large loads (50 megawatts or greater)
Minimum demand and minimum energy billing requirements to ensure these customers pay for the capacity and energy needed to serve them
Performance assurance and collateral requirements to secure customer payment and performance obligations
Termination cost provisions designed to address costs remaining if a customer reduces load or terminates service before the end of the contract term

These provisions are intended to ensure that customers taking large new loads are responsible for the costs associated with serving those loads and that existing customers do not subsidize these large new load customers.

Studies, Agreements, and Montana Public Service Commission Oversight

Under the proposed tariff, prospective large new load customers first enter into a development agreement and fund studies to evaluate system impacts, infrastructure needs, and service feasibility. The results of those studies are incorporated into an electric service agreement, which includes required customer protections under the tariff.

NorthWestern Energy's Large New Load Tariff establishes a consistent, Montana Public Service Commission-approved framework for onboarding new or expanded customers with an expected load of 5 megawatts or more, including a standardized study process and required Electric Service Agreement protections.

For the largest commitments, 50 megawatts or greater, NorthWestern Energy must file the executed Electric Service Agreement with the Montana Public Service Commission for review and approval before service begins. For customers with loads between 5 and 49 megawatts, the tariff's standardized process and mandatory protections apply, but individual agreements do not require case-specific Montana Public Service Commission approval filings.

Public Review Process

The Montana Public Service Commission is the authority for reviewing and approving electric tariffs in the state. NorthWestern Energy's application initiates a public regulatory proceeding that will include opportunities for review and public comment consistent with Montana Public Service Commission procedures. NorthWestern Energy's priority throughout the process is to provide safe, reliable energy service to customers at affordable rates.

"We look forward to working collaboratively with commissioners, stakeholders, and our customers," Bird said. "Our goal is a solution that protects Montanans, supports reliable electric service, strengthens Montana's energy infrastructure, drives responsible economic growth, and is right for Montana's unique situation."

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NorthWestern Energy - Delivering a Bright Future

NorthWestern Energy Group, Inc., doing business as NorthWestern Energy, provides essential energy infrastructure and valuable services that enrich lives and empower communities while serving as long-term partners to our customers and communities. We work to deliver safe, reliable, and innovative energy solutions that create value for customers, communities, employees, and investors. We do this by providing low-cost and reliable service performed by highly-adaptable and skilled employees. We provide electricity and / or natural gas to approximately 850,300 customers in Montana, South Dakota, Nebraska, and Yellowstone National Park. Our operations in Montana and Yellowstone National Park are conducted through our subsidiary, NW Corp, and our operations in South Dakota and Nebraska are conducted through our subsidiary, NWE Public Service. We have provided service in South Dakota and Nebraska since 1923 and in Montana since 2002.

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Investor Relations Contact:

Travis Meyer (605) 978-2967

travis.meyer@northwestern.com

Media Contact:

Jo Dee Black (866) 622-8081

jodee.black@northwestern.com

NorthWestern Energy Submits Large New Load Tariff Proposal to Strengthen Customer Safeguards and Support Montana's Energy Future and Economic Growth