Committee publication · Estimate memoranda · 11 February 2026
Department for Energy Security and Net Zero Supplementary Estimate Memorandum 2025-26
Summary
DESNZ's Supplementary Estimate for 2025-26 seeks £2.07bn Resource DEL, £11.73bn Capital DEL, £81.02bn Resource AME, and £80.4m Capital AME. Key drivers include £1.285bn for Sizewell C following Final Investment Decision, £21.9m for Prax oil refinery insolvency costs, and £29.01bn increase in nuclear decommissioning provisions following a comprehensive Sellafield review. The department targets energy security, bill protection, economic growth, and emissions reduction.
Key findings
- Sizewell C Final Investment Decision triggered £1.285bn Reserve claim for capital funding, plus £215m additional budget utilising underspends elsewhere
- Prax Group Lindsey Oil refinery insolvency (June 2025) required £21.9m additional Resource DEL for Official Receiver indemnity costs not foreseen at Main Estimate
- Nuclear Decommissioning Authority provisions increased £29.01bn (800.5% increase) due to comprehensive review of Sellafield decommissioning plan and revised Geological Disposal Facility cost estimates
- Resource AME decreased £6.5bn for Contracts for Difference fair value movements and £11.1bn for CCUS/Hydrogen whole-life costs reflecting reduced contract signings
- Department plans £157m annual RDEL efficiencies by 2028-29 through workforce digital reform, AI deployment, and delivery activity optimisation
Tone
ProceduralTopics
Key actors
Department for Energy Security and Net Zero (DESNZ), Nuclear Decommissioning Authority (NDA), Clive Maxwell (Interim Head of Department/Accounting Officer), Martin Gaunt (Interim Chief Financial Officer), HM Treasury, Prax Group, Sellafield, Great British Energy
Notable line
“£29,010.0 million increase in Nuclear Decommissioning Authority Nuclear Provisions (largely due to a comprehensive review of the Sellafield plan and a revised estimate of the cost of the Geological Disposal Facility).”
Key Quotes
“The Department for Energy Security and Net Zero (DESNZ) leads on the government's mission to make the UK a clean energy superpower and aims to achieve the following outcomes: • Enhance energy security • Protect bill payers • Create economic growth for the UK and generate and protect jobs • Reduce the UK's emissions Details of which …”
“Additional funding has been provided for depreciation and impairments following a review of ringfenced budgets. These budgets will from 2026-27 fall into Annually Managed Expenditure, reflecting the volatility of these costs.”
“The department has an efficiency plan to deliver £157m of RDEL annual efficiencies by 2028-29. This will be achieved through: • workforce and digital reform – improving productivity by using AI, better use of digital platforms and technology, insourcing expertise and increasing use of shared services …”
“Following the insolvency of Prax Group's Lindsey Oil refinery, as notified to Parliament on 1 st July 2025 3 , the Department has provided an indemnity to the Official Receiver for costs incurred in the insolvency process.”
“… upon the successful conclusion of the Final Investment Decision (FID) for Sizewell C, additional funding of £1,285m was required which HMT had already agreed will be funded by a claim on the Reserve.”
Source · parliament.uk record ↗