Who has to comply with ESOS Phase 4?
Your organisation is in scope if, on 31 December 2026, it's a large undertaking, meaning either:
- it has 250 or more employees, or
- it has annual turnover over £44 million and a balance sheet over £38 million.
Corporate groups are assessed together, so a smaller UK subsidiary of a large group is usually in scope too. Proposed changes to align thresholds with SECR were dropped, so the criteria are the same as Phase 3.
What's changed for Phase 4
- Fewer compliance routes. Display Energy Certificates and Green Deal Assessments can no longer be used, so most businesses need a Lead Assessor-led audit or ISO 50001 certification.
- Action plan accountability. Your Phase 4 notification must review the measures in your Phase 3 action plan, and explain any you didn't implement.
- Net zero focus postponed. Plans to broaden ESOS towards net zero have been pushed back to Phase 5 (2027 to 2031).
Key ESOS dates
| Milestone | Date | |---|---| | Phase 3 second progress update | 5 December 2026 | | Phase 4 qualification date | 31 December 2026 | | Phase 4 compliance notification | 5 December 2027 | | Phase 4 action plan due | 5 December 2028 |
Audits must cover at least 90% of your total energy consumption, so for a multi-site manufacturer, scoping the data takes time. Starting early avoids a rushed and expensive audit next autumn.
Turning ESOS into actual savings
An ESOS audit lists energy-saving opportunities but doesn't buy your energy or fix your bills. Many of the fastest paybacks on a manufacturing site are commercial rather than technical:
- Capacity (kVA) right-sizing
- Levy relief through BICS, EII or CCA
- Better contract timing
- Recovering overcharged non-commodity costs
Our free audit looks at those levers first, so your ESOS action plan includes savings you can bank this year.
Frequently asked questions
The ESOS Phase 4 compliance notification must be submitted to the Environment Agency by 5 December 2027. The qualification date is 31 December 2026.
It applies if, on 31 December 2026, your organisation (including its UK group) has 250 or more employees, or has turnover over £44 million and a balance sheet over £38 million.
The Environment Agency can issue civil penalties for non-compliance, including fixed and daily penalties, and may publish details of non-compliant businesses.
Yes. ISO 50001 certification covering your energy use remains a valid route to ESOS compliance. Display Energy Certificates and Green Deal Assessments no longer are.