ESOS compliance · the order of work
ESOS compliance
ESOS compliance is not one filing but a chain of duties in the ESOS Regulations 2014, each leaving evidence the next one relies on.
For Phase 4 the chain runs from the qualification date of 31 December 2026 to the notification on 5 December 2027, then on through the action plan to 2031.
This guide sets the duties out in statutory order, with the provision, the output and who signs.
Step zero
Compliance starts with the qualification test
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Key point 01
Module 02 / 04
Boundary
Module 03 / 04
Reporting period
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Boundary · 2
ESOS: at least 250 persons, or over £44m turnover and over £38m balance sheet.
SECR: exempt on two or more of not more than £36m, £18m and 250 employees.
Neither decides the other.
Read the detailed guidance and evidence
The duties apply to a relevant undertaking, which Schedule 1 defines by size on the qualification date, 31 December 2026.
Every UK member of a group containing a large undertaking comes in, and by default the highest UK parent carries the duties as the responsible undertaking.
The test itself, with the monthly-average headcount and the two-period status rule, is on ESOS Phase 4 thresholds.
SECR has a different test, in Schedule 7 Part 7A of the 2008 accounts regulations, so a group can be in one and not the other.
The SECR side is set out on SECR thresholds.
The chain
The Phase 4 duties, step by step
Each step is a duty in the Regulations, and each produces a record the notification or the evidence pack will need.
The order is the order in which the later steps depend on the earlier ones.
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1
Module 03 / 04
3
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4
Read the detailed guidance and evidence
| # | Duty | What it produces | Provision |
|---|---|---|---|
| 1 | Confirm qualification on 31 Dec 2026 | A record of the size test for every undertaking in the group | Sch 1; reg 15 |
| 2 | Calculate total energy consumption | A 12-month figure, in kWh or energy spend | reg 22 |
| 3 | Identify significant consumption (optional) | Areas making up at least 95%, and the de minimis left out | reg 25 |
| 4 | Calculate energy intensity ratios | kWh per indicator, for each organisational purpose used | reg 25C |
| 5 | Appoint a lead assessor | From an approved register, unless exempt | reg 21 |
| 6 | Audit, or rely on ISO 50001 | Audit records, or the certificate and its scope | regs 26–27, 33 |
| 7 | Produce the ESOS report | Including savings achieved and the action plan review | regs 27A, 27D, 27E |
| 8 | Responsible officer confirmation | One or two officers, depending on the lead assessor | regs 30–31 |
| 9 | Notify through MESOS | By 5 Dec 2027 | reg 29 |
| 10 | Keep the evidence pack | Every record above, kept for enquiries | reg 28 |
| 11 | Action plan, then three progress updates | By 5 Dec 2028, then 2029, 2030, 2031 | regs 34A–34B |
The calculation in step 2 must be made on or after the qualification date, on assets held and activities carried on that day, over 12 consecutive months ending on or before 5 December 2027, under regulation 22.
Step 3 is a choice: a participant that does not identify its significant consumption must cover all of it.
Step 4 needs one ratio for each of transport, industrial processes, buildings and any other purpose the participant actually used energy for.
Step 5 falls away below 40,000 kWh, where an ISO 50001 system covers the energy, or where consumption is zero, under regulation 21 and regulations 33 and 33A.
In Phase 4 the lead assessor also owes a personal duty: to tell its approval body within seven days that the assessment is complete.
Step 6 is the audit, whose content is on ESOS energy audits, or the certificate, covered on ISO 50001 and ESOS.
Step 7 carries the two Phase 4 additions: the energy savings actually achieved in the compliance period, in kWh, and a review of the measures in the last action plan that were not implemented.
Step 11 is covered on the ESOS action plan, and regulation 28 of SI 2026/701 is what makes Phase 4’s progress updates three rather than two.
Who signs
The responsible officer: one signature or two
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Lead assessor independent of the participant
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Lead assessor not independent (for example,
Module 03 / 04
No lead assessor: under 40,000 kWh
Module 04 / 04
No lead assessor: zero energy
| Case | Officers |
|---|---|
| Lead assessor independent of the participant | One |
| Lead assessor not independent (for example, an employee) | Two |
| No lead assessor: under 40,000 kWh | Two |
| No lead assessor: zero energy | Two |
Read the detailed guidance and evidence
The instrument’s word is responsible officer: a director within section 250 of the Companies Act 2006, or a person exercising management control.
“Board level” appears in the guidance, not in the Regulations.
Regulation 30(3) asks for one officer where the lead assessor is independent of the participant, and two in any other case.
Independence is a statutory test: in the last 12 months the assessor must not have been an employee, director, partner or shareholder of the participant, or the spouse or civil partner of one.
So an outside consultant who holds shares, or was an employee ten months ago, is not independent, and two officers sign.
From Phase 4 the confirmation also covers any certified energy management system the participant relies on, under regulation 31 as amended by SI 2026/701.
The record
The evidence pack, and why it is the real deliverable
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Deadline
Module 02 / 04
Legal route
Module 03 / 04
Method
Module 04 / 04
Legal route · 2
Written agreements on who is the responsible undertaking, and any disaggregation.
What you excluded from total consumption, and why.
The reasons for, and method of, every estimate.
Read the detailed guidance and evidence
The notification tells the regulator what you did; the evidence pack is what it asks for if it checks.
Regulation 28 lists what the pack must hold, and failing to keep it is the regulation 44 penalty: £5,000 plus the regulator’s cost of confirming compliance.
SI 2026/701 added two things to the list: the methods and data behind any estimate, and the action plan review.
The audit itself must record, under regulation 26(9), when it was done, the 12 months it covers, the sites that exist, the sites visited, and why those were representative.
The Environment Agency’s guidance adds the group paperwork: a written agreement for any responsible undertaking other than the highest UK parent, and for any disaggregation.
Disclosure
What the regulator publishes, and what it keeps
Module 01 / 04
ESOS report
Module 02 / 04
Combined energy savings achieved, in kWh
Module 03 / 04
Savings measure by measure
Module 04 / 04
Action plan review (unimplemented measures a
Read the detailed guidance and evidence
| Item | Notified? | Published? |
|---|---|---|
| ESOS report | Contents summarised in the notification | No |
| Combined energy savings achieved, in kWh | Yes | Yes — new in Phase 4 |
| Savings measure by measure | Yes | No |
| Action plan review (unimplemented measures and why) | Yes | No |
| ISO 50001 route details (Table K) | Yes | No |
| Action plan | Yes | Yes |
| Progress updates | Yes | Yes |
Phase 4 publishes more than Phase 3, not less: the combined savings figure is new, and two rows of Table G changed from unpublished to published.
The action plan review is the exception, notified and withheld.
Because action plans and progress updates are public, a missed one is visible against everyone who filed, even though no penalty attaches to it.
Reusing data
Other schemes’ data is a start, not a substitute
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Disclosure
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Key point 02
Module 03 / 04
Method
Module 04 / 04
Key point 04
Read the detailed guidance and evidence
The Environment Agency lists UK ETS, climate change agreements, quoted-company greenhouse gas reporting, SECR, climate-related financial disclosures, and the old DEC and Green Deal routes.
Its guidance is plain: participation in those schemes does not automatically count as ESOS compliance for the energy they cover.
Their data can feed the total energy calculation, but ESOS covers more energy than any of them, so extra work is likely.
An energy audit done under a climate change agreement may count as an ESOS audit, but only if a qualified lead assessor carried it out or reviewed it and it meets the ESOS minimum.
Holding the data once for ESOS, SECR and UK SRS is the subject of ESOS and UK SRS, and the wider duties on ESG reporting requirements in the UK.
The platforms that hold it are surveyed on carbon management software, and UK SRS itself on the UK SRS hub.
If it goes wrong
Missing a step, and what follows
Module 01 / 04
Legal route
Module 02 / 04
Deadline
Module 03 / 04
Deadline · 2
Module 04 / 04
Key point 04
Read the detailed guidance and evidence
The sanctions are the five civil penalties in Part 8 of the Regulations, each with the option of publication.
The ones a compliance programme can trip are failing to notify, failing to undertake the assessment, failing to keep records, and making a false or misleading statement in the notification.
Phase 4 puts more figures into the notification, including the savings achieved, which makes the accuracy of what goes into it matter more than it did.
The action plan and progress updates carry no penalty of their own; the failure is published instead.
The Phase 4 guidance asks anyone who expects to miss the compliance date to follow the steps in its enforcement section and contact the ESOS helpdesk.
The amounts and how they are set are on ESOS penalties, and the whole cluster is indexed on the ESOS hub.
Further reading
Where else to read
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Key point 01
Module 02 / 03
Disclosure
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Disclosure · 2
Read the detailed guidance and evidence
The GOV.UK ESOS overview lists the seven approved lead assessor registers, and it is the place to check that a named assessor is on one.
The sister reference covers the scheme at length in its ESOS reference guide and its Phase 4 compliance guide, and the disclosure side in UK SRS S2.
How ESOS and SECR work together in practice is set out by srsreport.co.uk, and the sister reference sets out what to check before appointing an ESOS lead assessor.
Frequently asked
ESOS compliance: questions people ask
What does ESOS compliance involve?
For Phase 4: calculate total energy consumption over a 12-month reference period; optionally identify the areas making up at least 95% of it; calculate an energy intensity ratio for each organisational purpose; appoint a lead assessor unless exempt; carry out an energy audit or rely on ISO 50001 for that energy; produce the ESOS report; have one or two responsible officers confirm it; notify through MESOS by 5 December 2027; keep an evidence pack; then file an action plan and three progress updates.
Who signs off an ESOS assessment?
The responsible officer: a director within section 250 of the Companies Act 2006, or a person exercising management control.
Regulation 30(3) requires one where the lead assessor is independent of the participant, and two in any other case.
Two are also needed where no lead assessor is required because consumption is under 40,000 kWh.
What is the ESOS evidence pack?
The records a responsible undertaking must keep under regulation 28 to show how it complied: how total and significant consumption were calculated, how each audit was carried out, the methods and data behind any estimate, the ESOS report and, from Phase 4, the action plan review.
Failing to keep it is penalised under regulation 44.
Is the ESOS report published?
No, but some of what is notified is.
The Environment Agency publishes each action plan and progress update, and in Phase 4 also publishes the combined energy savings achieved.
The review of unimplemented action plan measures is notified but not published.
Can SECR or UK ETS data be used for ESOS?
It can feed the calculation, but it does not count as ESOS compliance.
The Environment Agency's guidance says data collected for UK ETS, climate change agreements, SECR or other schemes can help calculate total energy consumption, but ESOS covers a wider scope and further work is likely.
When do ESOS Phase 4 duties have to be done?
The assessment and notification by 5 December 2027; the action plan by 5 December 2028; progress updates by 5 December 2029, 2030 and 2031.
Total energy consumption is measured over 12 consecutive months beginning no more than 12 months before 31 December 2026.
What if we are going to miss the ESOS deadline?
The Environment Agency's Phase 4 guidance sets out the steps in its section on enforcement and asks participants to contact its ESOS helpdesk at esos@environment-agency.gov.uk.
Missing the notification risks the regulation 43 penalty, and missing the assessment the regulation 45 penalty.
Prepare the evidence
ESOS compliance: from a requirement to a reporting pack
Use this preparation sequence alongside the detailed requirements on this page.
An editorial workflow, not a statutory schedule.
- Stage 0101
Qualification record
Resolve the undertaking and group position at the qualification date.
- Stage 0202
Energy period
Retain the chosen reference period and its source records.
- Stage 0303
Assessment coverage
Document the audit coverage, exclusions and compliance routes used.
- Stage 0404
Assessor review
Check whether a lead assessor is needed for the chosen compliance route.
- Stage 0505
Approval and notification
Retain the applicable director sign-off and notification evidence.
- Stage 0606
Action plan
Use the assessment findings to support the applicable action plan and progress record.
Read the applicable instrument: The Energy Savings Opportunity Scheme Regulations 2014 (SI 2014/1643), revised text
A practical brief
An evidence pack, with a clear review trail
Ask for a pack that lets the next reviewer retrace the scope decision, follow the evidence and understand the limitations.
This describes a useful handover; it does not certify compliance or establish that a vendor or adviser delivers it.
Module 01 / 04
Applicability record
Write down the entity, reporting route and relevant period, including why the route applies.
Module 02 / 04
Evidence register
Attach each reported figure or statement to its source, method, version and limitations.
Module 03 / 04
Review trail
Name the preparer, reviewer, open questions and decisions taken before publication.
Module 04 / 04
Usable handover
Retain the working files and unresolved actions so the next reporting cycle can reuse the evidence.
View the preparation diagram
- Prepare01
Create the traceable pack
Keep the input records, calculation files and narrative together.
- Challenge02
Resolve questions before publication
Record the assumptions challenged and any limitations still unresolved.
- Retain03
Make the next cycle reproducible
Keep the approved version and the actions carried forward.
Continue your research
Related guides, one question at a time
Sources
Primary sources
Every figure, date and status on this page traces to the instrument’s owner.
Secondary commentary is never the source for a number.
- legislation.gov.ukThe Energy Savings Opportunity Scheme Regulations 2014 (SI 2014/1643), revised text
In force 17 July 2014. Consolidation of the 2026 amendments is partial — read with SI 2026/701.
- legislation.gov.ukESOS Regulations 2014, Schedule 1 ¶¶1, 1A, 5, 9–11 — the large undertaking test
At least 250 persons, or turnover in excess of £44m and balance sheet in excess of £38m; monthly-average headcount (¶10); two-period status rule (¶11).
- legislation.gov.ukESOS Regulations 2014, regulation 22 — total energy consumption and the reference period
Reference period begins no more than 12 months before the qualification date and ends on or before the compliance date (reg 22(5)).
- legislation.gov.ukESOS Regulations 2014, regulation 25 — areas of significant energy consumption
Not less than 95% of the total, by energy units or by spend; identification is elective.
- legislation.gov.ukESOS Regulations 2014, regulation 25C — energy intensity ratios
One for each organisational purpose.
- legislation.gov.ukESOS Regulations 2014, regulation 21 — the lead assessor
Reg 21(3): not required below 40,000 kWh of total energy consumption.
- legislation.gov.ukESOS Regulations 2014, Part 4 Chapter 3 (regulations 26–27) — the energy audit
Audit data window (reg 26(4)), site visits (26(3A)), audit records (26(9)) and what an audit must identify and estimate (reg 27).
- legislation.gov.ukESOS Regulations 2014, regulation 29 — notification of compliance
The Schedule 3 tables each route must provide, by the compliance date.
- legislation.gov.ukESOS Regulations 2014, Part 6A (regulations 34A–34B) — action plans and progress updates
Consolidated to 22 July 2026: contents, windows, kWh basis, the third progress update, the zero-energy carve-out.
- legislation.gov.ukESOS Regulations 2014, Part 8 (regulations 39–47) — civil penalties
The five penalties and publication; regulations 34A and 34B are named nowhere in Part 8.
- legislation.gov.ukThe Energy Savings Opportunity Scheme (Amendment) Regulations 2026 (SI 2026/701)
Made 23 June 2026, in force 22 July 2026: the Phase 4 changes. Made under Energy Act 2023 ss.254–260 and 263.
- legislation.gov.ukSI 2026/701, regulation 28 — the third progress update (new reg 34B(1)(c))
- Environment AgencyHow to comply with the Energy Savings Opportunity Scheme (ESOS) phase 4
Published 30 July 2026. A restatement of the Regulations, never the source over them; where it and the SI differ, the SI governs.
- Environment AgencyComply with the Energy Savings Opportunity Scheme (ESOS) phase 4 — publication page
- Environment Agency / GOV.UKEnergy savings opportunity scheme (ESOS): find out if you qualify and how to comply
Rewritten for Phase 4 on 2 September 2026; seven approved lead assessor registers; PAS 51215-1 and -2:2025 voluntary.
- legislation.gov.ukSI 2008/410 Schedule 7 Part 7A — SECR for large unquoted companies
The two-or-more exemption test at £36m, £18m and 250 — a different regime.
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