Delivery Body Updates & Events

We are announcing the release of essential documents for the T-1 (Delivery Year 2026/27) and T-4 (Delivery Year 2029/30) Capacity Auctions, scheduled for 2026. These documents include the Auction Parameters, Auction Guidelines, Electricity Capacity Report (ECR), and Demand Incentive Letter.

You can access these documents here, or directly via the links in the headers below:

• Auction Guidelines and User Guide: This document provides comprehensive information specific to the auctions, including dates, parameters, and De-Rating Factors.
• SoS Auction Parameters Letter and Annex - Parameters Information: Official correspondence from the Secretary of State to NESO, confirming the Auction Parameters for the T-1 and T-4 Auctions.
• Demand Incentive Letter: A summary of the initiatives undertaken to improve the Peak System Demand Forecast.
• Electricity Capacity Report 2025: Presented in an accessible format, this report includes NESO's recommendations for total capacity procurement and unique De-Rating Factors for each auction, along with supporting analysis, assumptions, and outcomes from modelling development projects.
• Electricity Capacity Report 2025 Data Workbook: A consolidated spreadsheet containing all numerical tables and charts.
• Methodologies and Assumptions Book: Details the methodology used to determine Storage De-Rating Factors.

If you have any questions, please contact the Capacity Market Prequalification and Auction Team at [email protected], or call 01926 655300 (Option 1). Our telephone lines are open from 9:00 am to 5:00 pm, Monday to Thursday, and from 9:00 am to 4:00 pm on Fridays.

For inquiries specifically about the Electricity Capacity Report (ECR), please reach out to the Modelling team at [email protected]. 

Consultation Overview

Following the recent publication of the consultation, “Conditional Prequalification for assets eligible for an accelerated grid connection agreement through the Connections Reform Package”, the government proposes to allow Transmission Network Connected New Build CMUs with a Grid Connection Agreement which commences after 2029/2030 to apply for the 2025 Prequalification, provided they have requested an accelerated connection from NESO. You can view the full consultation here. 

We encourage Capacity Market customers to respond promptly to ensure their views are considered. For any questions or further clarification, please contact Ofgem or DESNZ directly. 

Connections Customer Guidance 

To support Applicants in preparing for the upcoming Capacity Auctions, the Delivery Body has published guidance on how the Connections Reform Programme aligns with Capacity Market Rules and Regulations. This guidance outlines the Delivery Body’s approach to assessing Prequalification Applications and is intended to help Applicants navigate the process. 

Capacity Market and Connections Reform

The Delivery Body cannot pre-empt the outcome or timelines of the Connections Reform Programme. The Delivery Body will assess the information submitted by the Applicant within the Application, based on the details available at the point when the Prequalification submission window closes. 

Please note, all Guidance should be read in conjunction with the Capacity Market Rules and Regulations.

Impact on Operational Plan for 2025/26

In light of the resulting uncertainty around the operational timeline for the 2025/26 Prequalification and Auction window, the opening of the Prequalification Submission Window has been rescheduled from 22 July to 5 August 2025.

The Operational Plan for 2025/26 has been updated to reflect the revised Prequalification dates.

You can access the updated Operational Plan here.

If you have any questions, please contact the Capacity Market Prequalification Team at [email protected] or call 01926 655300 (Option 1). Telephone lines are open from 9:00 am to 5:00 pm, Monday to Thursday, and from 9:00 am to 4:00 pm on Fridays.

Overview

The One-Year-Ahead Capacity Market Auction for Delivery Year 2026/27 (T-1) will begin on 24 February 2026.

This page provides important updates on milestones, pre-auction activities, and key dates. For more detailed information, please visit our Auction guidance website here.

Key Dates

Planning Consent Deadline

Each Applicant for a Prospective Generating CMU must declare they have obtained or will obtain all Relevant Planning Consents required for the construction and commissioning of the Prospective Generating Plant (excluding any ancillary infrastructure associated with, but not comprised in, the plant) and have the legal right to use the land where the CMU is or will be located. For more information, visit our guidance here. The deadline for T-1 is the 30 January 2026.

Confirmation of Entry Window

All Applicants for Prequalified New Build Generating/Interconnector CMUs, Refurbished Generating/Interconnector CMUs, and Proven/Unproven DSR CMUs must confirm their participation as a Bidder for the T-1 Auction. This must be completed within the Confirmation of Entry window, from 09:00 on 10th February 2026 to 17:00 on 17 February 2026. Failure to do so will result in the CMU not being enrolled in the Auction. For more information, please visit our guidance here.

Mock Auction

The T-1 Mock Auction on 19 February 2026 provides participants with the opportunity to verify their credentials and CMU portfolio before the live T-1 Auction. While not mandatory, it is highly recommended to log in and review details. Participants can practice submitting bids and DBAs using a DB script. Mock Auction guidance will be issued a few days prior to the event.

Live Auction

The T-1 Live Auction will take place on 3 February 2026. All activities for the Auction are to be completed within 2 days. The first round of each day will last 1 hour, with subsequent rounds lasting 30 minutes each. There will be a 15-minute recess between each round to allow the Auctioneer and the EMR Delivery Body to verify the round results. Round-by-round updates will be available here.

When the Auction clears, the EMR Delivery Body will announce the Clearing Price range during the 15-minute recess after the round. The Provisional Results Report will be published later that evening or the following morning before 9AM, confirming the Clearing Price and the successful CMUs.

For more information on our Auction, please see last year's Auction Readiness slide pack here. The 2025 Auction Readiness Webinar will be released on Prequalifcation Results Day.  

Auction Results Day (ARD) and Capacity Agreement Notice (CAN) Release

Auction Results Day takes place 8 working days after the Auction clears. The T-1 Final Result Report will be published by the EMR Delivery Body either on 13 March or 16 March 2026, depending on when the Auction clears.

This year, Capacity Agreement Notices (CANs) will be issued 10 working days after Auction Results Day, on either 27 March or 30 March 2026, depending on when the Auction clears.

Overview

The Four-Year-Ahead Capacity Market Auction for Delivery Year 2028/29 (T-4) will begin on 3 March 2026.

This page provides important updates on milestones, pre-auction activities, and key dates. For more detailed information, please visit our Auction guidance website here.

Key Dates

Planning Consent Deadline

Each Applicant for a Prospective Generating CMU must declare they have obtained or will obtain all Relevant Planning Consents required for the construction and commissioning of the Prospective Generating Plant (excluding any ancillary infrastructure associated with, but not comprised in, the plant) and have the legal right to use the land where the CMU is or will be located. For more information, visit our guidance here. The deadline for T-4 is the 6 February 2026.

Confirmation of Entry Window

All Applicants for Prequalified New Build Generating/Interconnector CMUs, Refurbished Generating/Interconnector CMUs, and Proven/Unproven DSR CMUs must confirm their participation as a Bidder for the T-4 Auction. This must be completed within the Confirmation of Entry window, from 09:00 on 17th February 2026 to 17:00 on 24 February 2026. Failure to do so will result in the CMU not being enrolled in the Auction. For more information, please visit our guidance here.

Mock Auction

The T-4 Mock Auction on 26 February 2026 provides participants with the opportunity to verify their credentials and CMU portfolio before the live T-4 Auction. While not mandatory, it is highly recommended to log in and review details. Participants can practice submitting bids and DBAs using a DB script. Mock Auction guidance will be issued a few days prior to the event.

Live Auction

The T-4 Live Auction will take place on 10 March 2026. All activities for the Auction are to be completed within 2 days. The first round of each day will last 1 hour, with subsequent rounds lasting 30 minutes each. There will be a 15-minute recess between each round to allow the Auctioneer and the EMR Delivery Body to verify the round results. Round-by-round updates will be available here.

When the Auction clears, the EMR Delivery Body will announce the Clearing Price range during the 15-minute recess after the round. The Provisional Results Report will be published later that evening or the following morning before 9AM, confirming the Clearing Price and the successful CMUs.

For more information on our Auction, please see last year's Auction Readiness slide pack here. The 2025 Auction Readiness Webinar will be released on Prequalifcation Results Day.  

Auction Results Day (ARD) and Capacity Agreement Notice (CAN) Release

Auction Results Day takes place 8 working days after the Auction clears. The T-4 Final Result Report will be published by the EMR Delivery Body either on 20 March or 23 March 2026, depending on when the Auction clears.

This year, Capacity Agreement Notices (CANs) will be issued 10 working days after Auction Results Day, on either 7 April or 8 April 2026, depending on when the Auction clears.

Each year, the Delivery Body provides potential Capacity Market participants with details of the key Capacity Market implementation activities and milestones through this Operational Plan.

View the 2025/26 Operational Plan here

The Operational Plan sets out the activities and milestones required to operate the Capacity Market in 2025/26. The timeline for operation of the 2025/26 Capacity Market is based on the Capacity Market Regulations and Rules and covers the T-1 and T-4 Auctions.  

This plan brings together Governmental milestones and Delivery Partner milestones and is intended to provide a high-level overview of the steps involved in the operation of the Capacity Market, such that industry participants have the clarity they require to plan and manage their own operational activities.  

The Operational Plan is indicative and may be subject to change, it is a live document that will be updated if dates change because of a change in regulation or other reasons. This plan is a summary and does not replace or replicate the detailed operational plans that Government, Delivery Partners and individual industry participants may need to produce to manage their respective activities. 

The T-1 CANs for the Delivery Year 2025-2026 have now been released.

The T-4 CANs for the Delivery Year 2028-2029 have now been released.