[6-K] National Grid PLC Current Report (Foreign Issuer)

Rhea-AI Filing Summary

National Grid plc has submitted its response to Ofgem's RIIO-ET3 Draft Determination, welcoming the regulator's commitment to an £80 billion electricity transmission investment plan and changes to the financial package since the Sector Specific Methodology Decision. The company says the Draft Determination does not fully recognise the practical challenges of delivering a two-and-a-half-fold increase in transmission investment and has proposed changes to ensure the final framework is investable—by improving baseline returns and incentives—and workable—by simplifying funding mechanisms and reopener decision-making. National Grid will continue engagement with Ofgem ahead of the Final Determination in December and points to an executive summary of detailed responses on its RIIO-T3 homepage. The announcement includes a standard cautionary statement about forward-looking statements and risks.

Positive

• Ofgem's commitment to a £80 billion investment plan in electricity transmission, which supports substantial network expansion
• Recognition by Ofgem of urgency in delivering transmission upgrades, acknowledged by National Grid
• National Grid's proactive engagement with Ofgem and submission of detailed evidence and solutions ahead of the Final Determination

Negative

• Draft Determination deemed insufficiently aligned with the practical realities of delivering a 2.5x increase in investment, implying potential delivery risk
• Concerns over baseline returns and incentives suggest perceived risk of lower-than-required returns for investors if not adjusted
• Complex funding mechanisms and reopener decision processes are viewed as barriers to efficient project progress and cost recovery

Insights

Regulatory Affairs Specialist

TL;DR: National Grid pushes for stronger returns and simpler funding to make RIIO-ET3 deliverable amid a major investment ramp-up.

National Grid's response is focused on two practical requirements: securing a commercially attractive baseline return and streamlining the complex set of funding and reopener mechanisms. From a regulatory affairs perspective, this signals constructive engagement but firm disagreement on material aspects of the Draft Determination that affect project delivery risk and capital recovery. The firm's emphasis on both "investable" and "workable" outcomes highlights concerns that the current proposals could slow delivery or increase financing costs unless Ofgem adjusts the incentives and decision processes. Continued dialogue before the December Final Determination will be critical for aligning regulatory settings with the scale and pace of the planned network expansion.

Infrastructure Finance Analyst

TL;DR: The company is seeking regulatory changes to protect returns and cash recovery while scaling a large investment program.

National Grid frames the Draft Determination as insufficiently reflective of delivery realities for the planned £80 billion program and a 2.5x increase in investment. Key finance issues flagged are baseline return levels and an incentives framework that should enable a "globally competitive overall return," plus simpler funding mechanisms to ensure timely cost recovery. These points are material to capital providers because they affect the risk-adjusted return profile and the predictability of cash flows for the transmission business. The submission is therefore likely to be viewed as an attempt to limit regulatory risk ahead of the Final Determination rather than mere commentary.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER PURSUANT TO RULE 13a-16 OR 15d-16 UNDER THE SECURITIES EXCHANGE ACT OF 1934

Date: 27 August 2025

Commission File Number: 001-14958

NATIONAL GRID plc

(Translation of registrant’s name into English)

England and Wales

(Jurisdiction of Incorporation) 

1-3 Strand, London, WC2N 5EH, United Kingdom

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

☒  Form 20-F      ☐  Form 40-F

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):  ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):  ☐

Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12g3- 2(b) under the Securities Exchange Act of 1934.  ☐  Yes    ☒  No

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): n/a

EXHIBIT INDEX

Exhibit No.	Description
99.1	Exhibit 99.1 Announcement sent to the London Stock Exchange on 27 August 2025 — Response to Ofgem's RIIO-ET3 Draft Determination

Exhibit 99.1

27 August 2025

National Grid plc

Ofgem's RIIO-ET3 Draft Determination: Consultation Response

As part of the ongoing process to agree the RIIO-ET3 price control which covers our National Grid Electricity Transmission business, we have submitted our response to Ofgem's Draft Determinations.

We welcome the continued positive intent from Ofgem on the design of the framework. The commitment to an £80 billion investment plan in the electricity transmission sector, recognition of the need for urgency in delivery, and the changes Ofgem have made to the financial package since the Sector Specific Methodology Decision are all valuable steps forward.

However, the Draft Determination does not sufficiently recognise the practical realities of delivering the biggest expansion of the electricity system in more than a generation and the required two and a half times increase in investment in our transmission network. We have submitted evidence and solutions for the changes required by Final Determination to achieve a framework that is:

-     Investable by creating the conditions required to deliver the unprecedented increase in investment. Changes are needed in relation to the baseline return and the incentives framework to allow high performing networks to achieve a globally competitive overall return; and

-     Workable by streamlining the overly complex suite of funding mechanisms, and changing the approach taken by Ofgem to make decisions in reopener processes. A workable framework enables transmission owners to recover the efficient costs of their investment and allows them to progress projects at the pace expected by our stakeholders. 

Both investability and workability are necessary for transmission owners to be able to meet the commitments put forward in their business plans including accelerating the decarbonisation of the energy system, and cost savings for consumers.

As we move towards the Final Determination in December, we will continue to engage with Ofgem at all levels to agree a price control that attracts the investment needed to ensure the reliable and affordable flow of clean electricity whilst also meeting the ramp up in demand for power. A resilient, future-proofed network will be critical to economic competitiveness and growth for Britain in the years ahead.

The executive summary to the company's detailed responses can be accessed from our RIIO-T3 homepage.

Enquiries and contacts                                  

Investors and Analysts:

Angela Broad	+44 (0) 7825 351 918
Cerys Reece	+44 (0) 7860 382 264

Media:

Alex Roache +44 (0) 7843 802 006

CAUTIONARY STATEMENT

This announcement contains certain statements that are neither reported financial results nor other historical information. These statements are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. These statements include information with respect to National Grid's (the Company) financial condition, its results of operations and businesses, strategy, plans and objectives. Words such as 'aims', 'anticipates', 'expects', 'should', 'intends', 'plans', 'believes', 'outlook', 'seeks', 'estimates', 'targets', 'may', 'will', 'continue', 'project' and similar expressions, as well as statements in the future tense, identify forward-looking statements. This document also references climate-related targets and climate-related risks which differ from conventional financial risks in that they are complex, novel and tend to involve projection over long term scenarios which are subject to significant uncertainty and change. These forward-looking statements and targets are not guarantees of National Grid's future performance and are subject to assumptions, risks and uncertainties that could cause actual future results to differ materially from those expressed in or implied by such forward-looking statements and targets. Many of these assumptions, risks and uncertainties relate to factors that are beyond National Grid's ability to control or estimate precisely, such as changes in laws or regulations and decisions by governmental bodies or regulators, including those relating to current and upcoming price controls in the UK and rate cases in the US; the timing of construction and delivery by third parties of new generation projects requiring connection; breaches of, or changes in, environmental, climate change and health and safety laws or regulations, including breaches or other incidents arising from the potentially harmful nature of its activities; network failure or interruption, the inability to carry out critical non-network operations and damage to infrastructure, due to adverse weather conditions including the impact of major storms as well as the results of climate change, due to counterparties being unable to deliver physical commodities; reliability of and access to IT systems, including due to the failure of or unauthorised access to or deliberate breaches of National Grid's systems and supporting technology; failure to adequately forecast and respond to disruptions in energy supply; performance against regulatory targets and standards and against National Grid's peers with the aim of delivering stakeholder expectations regarding costs and efficiency savings, as well as against targets and standards designed to support its role in the energy transition; and customers and counterparties (including financial institutions) failing to perform their obligations to the Company. Other factors that could cause actual results to differ materially from those described in this announcement include fluctuations in exchange rates, interest rates and commodity price indices; restrictions and conditions (including filing requirements) in National Grid's borrowing and debt arrangements, funding costs and access to financing; regulatory requirements for the Company to maintain financial resources in certain parts of its business and restrictions on some subsidiaries' transactions such as paying dividends, lending or levying charges; the delayed timing of recoveries and payments in National Grid's regulated businesses, and whether aspects of its activities are contestable; the funding requirements and performance of National Grid's pension schemes and other post-retirement benefit schemes; the failure to attract, develop and retain employees with the necessary competencies, including leadership and business capabilities, and any significant disputes arising with National Grid's employees or breaches of laws or regulations by its employees; the failure to respond to market developments, including competition for onshore transmission; the threats and opportunities presented by emerging technology; the failure by the Company to respond to, or meet its own commitments as a leader in relation to, climate change development activities relating to energy transition, including the integration of distributed energy resources; and the need to grow the Company's business to deliver its strategy, as well as incorrect or unforeseen assumptions or conclusions (including unanticipated costs and liabilities) relating to business development activity, including the proposed sale of certain of its businesses, its strategic infrastructure projects and joint ventures. For further details regarding these and other assumptions, risks and uncertainties that may affect National Grid, please read the Strategic Report section and the 'Risk factors' on pages 210 to 215 of National Grid's Annual Report and Accounts for the year ended 31 March 2025 published on 29 May 2025. In addition, new factors emerge from time to time and National Grid cannot assess the potential impact of any such factor on its activities or the extent to which any factor, or combination of factors, may cause actual future results to differ materially from those contained in any forward-looking statement. Except as may be required by law or regulation, the Company undertakes no obligation to update any of its forward-looking statements, which speak only as of the date of this announcement. This announcement is for informational purposes only and does not constitute an offer to sell or the solicitation of an offer to buy any securities. The securities mentioned herein have not been, and will not be, registered under the Securities Act or the securities laws of any state or other jurisdiction, and may not be offered or sold in the United States absent registration or an applicable exemption from registration requirements. No public offering of securities is being made in the United States.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	NATIONAL GRID plc
	By:	Beth Melges
		Beth Melges Head of Plc Governance

Date: 27 August 2025

FAQ

What did National Grid (NGG) announce about Ofgem's RIIO-ET3 Draft Determination?

National Grid announced it has submitted a response to Ofgem's RIIO-ET3 Draft Determination, welcoming the £80 billion investment commitment but saying the Draft Determination does not fully recognise delivery realities and requesting changes to make the framework investable and workable.

What specific changes is National Grid seeking in its RIIO-ET3 response?

The company seeks changes to the baseline return and incentives framework to achieve a globally competitive overall return, and simplification of funding mechanisms and reopener decision-making to enable efficient cost recovery and project progress.

How large is the investment plan referenced in the announcement?

The announcement references an £80 billion investment plan in the electricity transmission sector.

When will the Final Determination occur and what will National Grid do next?

The Final Determination is scheduled for December and National Grid stated it will continue to engage with Ofgem at all levels to agree the price control ahead of that date.

Does this announcement include financial results or earnings data for NGG?

No, the announcement is a regulatory response and does not include earnings data or other reported financial results.