Your ESOS status is fixed on 31 December 2026
The qualification date is a snapshot you cannot move, and your submission needs twelve months of energy data covering it. Compliance is due 5 December 2027.
One decides whether you are in. The other is the deadline.
Qualification date. Your headcount and financials on this day decide whether Phase 4 applies to you.
Compliance and notification deadline with the Environment Agency.
Of energy data, and it has to cover the qualification date. Gaps in late 2026 cannot be fixed later.
250 people, or the financial test
A UK undertaking is in scope if, on 31 December 2026, it employs 250 or more people, or has an annual turnover above £44 million and a balance sheet total above £38 million. Corporate groups are assessed at group level, so a group can qualify even where no single entity would.
That threshold sits almost exactly where the mid-market does, which is why ESOS catches companies that have no CSRD obligation and no listing. If you have grown past 250 people since the last phase, Phase 4 is likely your first.
What compliance involves
- Measure total energy consumption across buildings, transport and industrial processes
- Audit a representative sample of that consumption
- Identify cost-effective energy saving opportunities
- Produce an action plan, and report progress against it
- Notify the Environment Agency by 5 December 2027
Two changes to watch
Display Energy Certificates and Green Deal Assessments are no longer accepted as compliance routes. Organisations that leaned on them in earlier phases need a different approach this time.
The twelve months of data must cover 31 December 2026. This is the part that catches people out. It is not twelve months of your choosing at some point before the deadline – the window has to span the qualification date, so metering gaps in late 2026 are not recoverable in 2027.
Where the platform stands today
Available now. Energy consumption data collection across sites and fuel types, conversion to a consistent basis with the factor source stored on each calculation, evidence attached at datapoint level, and the same controls and audit trail used for carbon reporting. If you are collecting energy data for SECR or Scope 1 and 2, you already hold most of what an ESOS assessment needs.
In development. ESOS-specific support is being built now: a qualification test against the 31 December 2026 snapshot, coverage tracking so you can see whether your twelve-month window actually spans the qualification date, audit sampling against total consumption, and an action plan register with progress reporting. This is in development and not yet released.
The useful thing you can do today is make sure the energy data for late 2026 is being captured properly, because that window closes on 31 December and cannot be reopened. See how energy and carbon data is collected.
Questions
What is the ESOS Phase 4 deadline?
The qualification date is 31 December 2026 and the compliance deadline is 5 December 2027. You must complete an ESOS assessment and notify the Environment Agency by 5 December 2027. The Phase 4 compliance period runs from 6 December 2023 to 5 December 2027.
Who qualifies for ESOS Phase 4?
A UK undertaking qualifies if, on 31 December 2026, it employs 250 or more people, or has an annual turnover above 44 million pounds and a balance sheet total above 38 million pounds. Corporate groups are assessed at group level.
What energy data do I need for ESOS Phase 4?
Your submission must include twelve months of energy data that covers the qualification date of 31 December 2026. That means the data collection period spans a date you cannot move, so gaps in late 2026 cannot be fixed retrospectively.
Can I still use a Display Energy Certificate for ESOS compliance?
No. Display Energy Certificates and Green Deal Assessments are no longer accepted as ESOS compliance routes, so organisations that relied on them in earlier phases need a different approach for Phase 4.
What does an ESOS assessment cover?
Total energy consumption across buildings, transport and industrial processes, energy audits of a representative sample of that consumption, identification of cost-effective energy saving opportunities, an action plan, and notification to the Environment Agency.
Get the 2026 data right while you still can
The qualification window closes on 31 December. A demo takes fifteen minutes.
No credit card required · 15-minute call · No obligation