Capacity Market auction: Auction Monitor report for T-1 auction for 2026 to 2027

The Capacity Market Auction Monitor, Deloitte, has produced a report in relation to the Capacity Market T-1 auction for the 2026 to 2027 delivery year.

2025 one year ahead Capacity Auction (T-1) Delivery Year 2026 to 2027: Auction Monitor report 
 


  PDF  ,  437 KB ,  19 pages

2025 one year ahead Capacity Auction (T-1) 
Delivery Year 2026/27 
Auction Monitor Report 
6 March 2026 

2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 
Deloitte LLP 
6 March 2026 
 
 
 
Contents 
 
1 
Assurance Report 
1 
2 
Background and Context 
4 
3 
Confirmation of Bidders to be awarded Capacity Agreements 
6 
Appendix A – In-scope Capacity Market Rules (Chapter 5) 
13 
Appendix B – Outline of Work Performed 
14 
 
 
 

2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 
Deloitte LLP 
6 March 2026 
 
1 
 
1 Assurance Report 
ISAE 3000 Independent Reasonable Assurance Report to National 
Energy System Operator Limited (NESO) (as Electricity Market Reform 
Delivery Body) on its compliance with selected requirements of the 
Capacity Market Rules, Regulations and the Auction Guidelines. 
1.1 
Scope 
We have performed assurance work over the extent to which the Delivery 
Body (“DB”) has complied with the selected requirements of Chapter 5 of the 
Capacity Market Rules and the Auction Guidelines (together the “Rules and 
Guidelines”) (updated 23 June 2025). In particular, we have considered the 
rules included in Chapter 5 of the Capacity Market Rules as listed in 
Appendix A (the “Applicable Rules”). 
A consolidated version of the detailed Capacity Market Rules is available here: 
https://assets.publishing.service.gov.uk/media/6911ba14cf24e9250d893e79/i
nformal-consolidation-cm-rules-2025.pdf with the subsequent amendments at 
the time of writing available 
here:https://www.gov.uk/government/publications/capacity-market-rules. 
In the context of this Report, the actions of the DB in performing the 2025 
one year ahead Capacity Auction (T-1) Delivery Year 2026/27 (“the 2025 T-1 
Auction”) is the “Subject Matter” and the Applicable Rules form the “Criteria” 
against which the Subject Matter has been evaluated. 
1.2 
Respective Responsibilities 
The DB as the Responsible Party is responsible for delivering the process and 
requirements for the 2025 T-1 Auction in accordance with the Capacity Market 
Rules. 
Our responsibility, as agreed with the DB, is to assess the actions performed 
by the DB in performing the 2025 T-1 Auction against the requirements of the 
Applicable Rules and to independently express a conclusion as to whether the 
process and actions undertaken by the DB comply with the requirements of 
the Applicable Rules. Other than as defined in our assurance procedures, we 
did not audit or otherwise test or verify the information given to us in the 
course of the Services. 
1.3 
Work Performed 
We conducted our work in accordance with the International Standard on 
Assurance Engagements 3000 (Revised) “Assurance Engagements Other Than 
Audits or Reviews of Historical Financial Information”. That standard requires 
that we plan and perform our work to obtain appropriate evidence about the 
subject matter of the engagement sufficient to support an opinion providing 
reasonable assurance. 

2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 
Deloitte LLP 
6 March 2026 
 
2 
 
An outline of the work we performed is included in Appendix B. Except to the 
extent expressly stated above, we did not subject the information contained 
in our Report or given to us by the DB to checking or verification procedures. 
The procedures we performed were not designed to and are not likely to 
reveal fraud. 
1.4 
Inherent limitations 
We obtained reasonable assurance over the actions performed by the DB in 
operating in performing the 2025 T-1 Auction against the requirements of the 
Applicable Rules. Inherent limitations exist in all assurance engagements. 
Any internal control structure, no matter how effective, cannot eliminate the 
possibility that fraud, errors or irregularities may occur and remain 
undetected. The procedures we performed were not designed to and are not 
likely to reveal fraud. 
Except to the extent expressly stated, we did not subject the information 
contained in our Report, given to us by the DB (including bids) or included in 
the input parameters provided by DESNZ to checking or verification 
procedures. 
1.5 
Basis of Opinion 
We believe that our work performed and evidence obtained provides a 
reasonable basis for our opinion. Our assurance report has been produced 
under our letter of engagement with the Responsible Party effective from 
26 June 2025. 
1.6 
Assurance Conclusion 
In our opinion the actions performed by NESO, in its role as the 
Capacity Market Delivery Body for Electricity Market Reform, have in 
all material respects, complied with the relevant sections of the Rules 
and Guidelines as detailed in Section 1.1 above in respect of the 2025 
T-1 Auc

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