Does ESOS Phase 4 apply to you? Find out before 31 December.
If your organisation counts as large on 31 December 2026, you are in ESOS Phase 4, and your assessment has to be completed and notified to the Environment Agency by 5 December 2027. The qualification date is now only three months away, and for many businesses the harder question comes first: does ESOS actually apply to us?
The answer depends on your staff numbers, your turnover and balance sheet, and the rest of your corporate group, which is why so many organisations aren’t sure. This guide explains who qualifies, what has changed for Phase 4 and what to do now. If you’d rather have a straight answer for your own business, our free ESOS and SECR checker tells you where you stand in about 2 minutes.
What ESOS is, and the dates that matter
The Energy Savings Opportunity Scheme (ESOS) requires large UK organisations to assess how much energy they use and where they could save it. It runs in four year phases, and Phase 4 is decided by your size on one fixed day.
| Date | What happens |
|---|---|
| 5 December 2026 | Progress update due on your Phase 3 action plan, if you took part |
| 31 December 2026 | Qualification date. Your size on this day decides whether you are in Phase 4 |
| 5 December 2027 | Compliance deadline. Complete your assessment and notify the Environment Agency |
| 5 December 2028 | Your Phase 4 action plan is due |
Your assessment has to cover 12 months of energy use that includes 31 December 2026, so the data you collect this winter is the data you’ll be judged on.
Who qualifies for ESOS Phase 4
Using your accounts for the financial year ending on, or in the 12 months before, 31 December 2026, you count as a large undertaking if you employ 250 or more people, or you have an annual turnover above £44 million together with a balance sheet total above £38 million. You only need to meet one of those two tests.
Three rules catch many organisations out:
- Your group counts. If any UK company in your corporate group meets the test, your whole UK group must take part, even the smaller companies within it.
- The 2 year rule. Your status only changes once you have been above or below the thresholds for 2 consecutive accounting periods, so a business that grew or shrank recently needs to check both years.
- UK branches of overseas companies are judged on the number of staff they employ who pay UK income tax.
Public bodies are generally excluded. The full rules are in the ESOS guidance on GOV.UK.
Not sure where you stand? Our checker applies all of these rules for you, including the group and 2 year rules, and can pull your company details straight from Companies House.
What has changed in Phase 4
If you took part in Phase 3, don’t assume this round will look the same. Two changes make Phase 4 more demanding:
- Fewer shortcuts. Display Energy Certificates and Green Deal Assessments no longer count as routes to compliance, so more of your estate needs a proper energy audit or ISO 50001 cover.
- Your last plan is checked. Your Phase 4 assessment must report progress against your Phase 3 action plan commitments and explain any you didn’t deliver.
The cost of getting it wrong is real, and the Environment Agency can also publish details of the non compliance.
Where SECR fits
Streamlined Energy and Carbon Reporting (SECR) is a separate requirement that often applies to the same businesses. Rather than an assessment every four years, it’s an annual disclosure in your directors’ report covering your UK energy use, Scope 1 and 2 emissions, an intensity ratio, your methodology and the efficiency actions you’ve taken.
| ESOS Phase 4 | SECR | |
|---|---|---|
| Who is in scope | 250 or more employees, or turnover above £44m together with a balance sheet above £38m. If one UK company in a group qualifies, the whole UK group is in. | UK companies and LLPs exceeding 2 of these 3: more than 250 employees, turnover above £36m, balance sheet above £18m. All UK quoted companies are in, whatever their size. |
| What you do | Audit at least 95% of your energy use, get a board director to sign it off and notify the Environment Agency. | Publish your energy use, Scope 1 and 2 emissions, an intensity ratio and your efficiency actions in your directors’ report. |
| How often | Every 4 years | Every financial year |
| Next deadline | 5 December 2027 | With your next annual report |
One point worth knowing: the Companies Act size thresholds rose in April 2025, but SECR kept its own tests. You can be medium sized for your accounts and still have to report under SECR. The government’s environmental reporting guidelines set out exactly what to include.
What to do before 31 December
The organisations that find ESOS easiest are the ones that start before the qualification date, while there’s still time to shape the data and the results.
- Confirm your position. Check your size and your group against the thresholds using the right year’s accounts, including the 2 year rule.
- Submit your Phase 3 progress update by 5 December 2026 if you took part last time, signed off by a board director.
- Get your metering right at every site. Your 12 month reference period must include 31 December 2026, and gaps in your data this winter become estimates you’ll have to justify later.
- Book your lead assessor early. Capacity tends to tighten in the final year of each phase.
- Deliver savings before your assessment, not after. Measures installed now show up in your report as real reductions rather than a list of opportunities, and give you evidence for your action plan.
This is where we help. Pulse gives you live, site level energy data for your reference period and SECR disclosures, and our own teams deliver the measures your audit is likely to flag, from voltage optimisation to refrigeration savings and solar, with before and after results you can show your board and the regulator.
Find out where you stand in 2 minutes
Answer 8 quick questions and see whether ESOS Phase 4 and SECR apply to you. Leave your details and we’ll email you a personalised action plan with your figures against every threshold, a dated timeline to December 2027, an evidence checklist for your sites and the savings measures that fit your business.
