ESOS Phase 4 is already in motion, and many organisations don’t realise the clock is ticking. 

The final deadline is December 2027, but the real trigger date is 31 December 2026. That’s when your staffing levels and financial position will decide whether compliance becomes mandatory. 

Does your business need to comply? 

You must participate in ESOS Phase 4 if, on 31 December 2026, your organisation: 

• Employs 250 or more people, 
  or 

• Has turnover above £44 million and a balance sheet total above £38 million. 

If you’re part of a group, one qualifying UK entity can bring the whole group into scope. 

Even if you don’t qualify today, growth before the qualification date could change that. 

What’s different in Phase 4? 

Phase 4 emphasises action and accountability. 

Organisations must: 

• Measure total energy consumption 

• Conduct compliant energy audits (or hold ISO 50001 certification) 

• Identify cost-effective savings opportunities 

• Demonstrate progress against energy-saving plans 

Alternative compliance routes such as Display Energy Certificates are no longer valid. 

There is also greater emphasis on progress reporting and maintaining supporting evidence. 

Why businesses should act early 

Although the final deadline is December 2027, leaving preparation too late can create risk. 

Starting early helps you: 

• Avoid last-minute pressure 

• Secure an ESOS Lead Assessor before demand increases 

• Gather accurate energy data 

• Identify savings opportunities sooner 

• Engage leadership and secure budget 

For many organisations, ESOS audits uncover savings that exceed the cost of compliance. 

Key dates 

• Qualification date: 31 December 2026 

• Compliance deadline: 5 December 2027 

If your organisation participated in ESOS Phase 3 and submitted an Energy Action Plan, your first progress report was due in December 2025. 

The second and final Phase 3 progress update is due in December 2026. 

These reporting requirements continue alongside preparation for Phase 4. 

ESOS Phase 4 is not just a regulatory exercise; it’s an opportunity to reduce energy costs, improve operational efficiency, and strengthen sustainability reporting. 

With the qualification date approaching, now is the right time to assess eligibility and begin preparation. 

Early action reduces risk and puts your organisation in control. 

If you are unsure whether ESOS Phase 4 applies to your organisation, or you need support with ESOS Phase 3 compliance updates, please get in touch at [email protected] or call 0203 157 1020 – our team can help you ensure you remain compliant.