Across all four organisational purposes: buildings, industrial processes, transport, and any other purpose.
Energy Savings Opportunity Scheme · Phase 4
ESOS Phase 4: every duty, every date, read against the law
ESOS Phase 4 is decided on one day, 31 December 2026, and due on another, 5 December 2027.
Between them sit eight duties set by the ESOS Regulations 2014 as amended by SI 2026/701, which came into force on 22 July 2026.
This site reads each one against the Regulations, and flags where the Environment Agency’s Phase 4 guidance says something different.
- Period openedPhase 4 compliance period6 Dec 2023
- In forceSI 2026/70122 Jul 2026
- Phase 3 plansSecond progress update due5 Dec 2026
- SnapshotQualification date31 Dec 2026
- DeadlineNotification of compliance5 Dec 2027
- NextPhase 4 action plan5 Dec 2028
- FinalThird progress update5 Dec 2031
Am I in?
Qualification is a snapshot on 31 December 2026
An undertaking is large if it employs at least 250 people, or has turnover in excess of £44 million and a balance sheet in excess of £38 million.
The two tests are worded differently on purpose: 250 employees is in, but £44 million exactly is not.
Both money limbs must be exceeded together; a company with £60 million turnover and a £30 million balance sheet is not large on the money test.
If any UK undertaking in a group qualifies, the whole UK group participates, and one responsible undertaking notifies for it.
The test is applied once, on the qualification date, so a sale or a restructuring in 2027 does not take a group out of ESOS Phase 4.
The qualification page takes groups, overseas parents and the insolvency exclusion in turn.
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Do you qualify for ESOS Phase 4?
Enter figuresEnter your figures as at 31 December 2026.Use employees, or turnover and balance sheet in £ million.SI 2014/1643 reg 4(3)(b)
A sterling test on the qualification date; groups, overseas parents and fund structures need the full rules.
Every date to 2031
One phase, eight years of dates
Every Phase 4 date comes from regulation 4, which runs each compliance period from 6 December to 5 December four years later.
The qualification date is the 31 December before the compliance date.
The energy data must cover twelve consecutive months that include 31 December 2026 and end on or before 5 December 2027, so calendar year 2026 is the earliest period that works.
Phase 4 does not end at the notification: the action plan and its three progress updates run to 2031, overlapping Phase 5.
- 6 Dec 2023Phase 4 compliance period beginsReg 4(2)
- 22 Jul 2026SI 2026/701 in forceThe Phase 4 changes take effect.SI 2026/701
- 30 Jul 2026Environment Agency Phase 4 guidance publishedGOV.UK
- 5 Dec 2026Phase 3 second progress update dueFor organisations that filed a Phase 3 action plan.Reg 34B
- 31 Dec 2026Qualification dateSize and group structure are tested on this day.Reg 4(3)(b)
- 5 Dec 2027Compliance dateNotification of compliance through MESOS.Reg 4(4)(b)
- 5 Dec 2028Phase 4 action plan dueReg 34A
- 5 Dec 2029 – 2031Three annual progress updatesThe third is new in Phase 4.Reg 34B(1)(a)–(c)
The assessment
The eight duties, in order
Scroll through the duties a participant works through between the qualification date and the deadline.
Each step names the regulation that imposes it.
- Part 4 Ch 2
Calculate total energy consumption
- Reg 25C
An energy intensity ratio for each purpose
Up to four ratios, one per organisational purpose that applies.
- Reg 25
Identify significant consumption
Assets and activities accounting for at least 95% of total consumption, by units or by spend.
95% minimum coverage
- Regs 26, 33
Audit it, or cover it with ISO 50001
An ESOS energy audit, or ISO 50001 certification covering total or significant consumption.
- Reg 21
Appoint a lead assessor
From an approved register, unless consumption is below 40,000 kWh or ISO 50001 covers it.
- Regs 27D, 27E
Report savings achieved and review the last plan
New in Phase 4: savings in kWh per measure, and why any Phase 3 action plan measure was not implemented.
- Reg 30
Responsible officer sign-off
One responsible officer if the lead assessor is independent; two otherwise.
- Reg 29
Notify compliance by 5 December 2027
Through the Environment Agency’s notification system, MESOS, after the qualification date.
Sign-off and the lead assessor rules are set out on the lead assessor and sign-off page.
SI 2026/701
What changed between Phase 3 and Phase 4
Phase 3
Four routes including DECs and GDAs, two progress updates, and no review of the last action plan.
Phase 4
Two routes, savings achieved and the last action plan reviewed in the report, and three progress updates.
Source: SI 2026/701 and its Explanatory Note.
The thresholds, the 95% floor and the dates logic did not change.
Lead assessors gained a personal duty: to notify their approval body within seven days of completing an ESOS assessment.
Estimates are now stated in kWh, and the insolvency exclusion covers proceedings at any point between the qualification date and the compliance date.
For a duty-by-duty compliance walkthrough, the family’s ESOS Phase 4 compliance guide on uksrs.org.uk sets out the eight duties against every deadline.
Enforcement
Five penalties, and one gap
The penalties are statutory, set in Part 8 of the Regulations, and each carries publication of the name, the breach and the amount.
None of them attaches to the action plan or progress updates, which is a gap in the Regulations rather than regulator forbearance.
For an organisation in its first compliance period, the Environment Agency says it will normally cap the initial penalty for failing to undertake an audit at £5,000.
The penalties page takes each offence in turn.
| Regulation | Failure | Maximum |
|---|---|---|
| 43 | To notify compliance | £5,000 + £500 per working day (80 max) |
| 44 | To keep records | £5,000 + audit costs |
| 45 | To undertake an ESOS assessment | £50,000 or less + £500 per working day (80 max) |
| 46 | To comply with a notice | £5,000 + £500 per working day (80 max) |
| 47 | False or misleading statement | £50,000 or less |
By the numbers
ESOS Phase 4 in figures from the law
250
employees makes an undertaking large, at least
Sch 1 ¶1
95%
of total consumption is the floor for significant consumption
Reg 25(2)
4
organisational purposes, each with its own intensity ratio
Regs 2(1), 25C
7
approved lead assessor registers on the GOV.UK list
GOV.UK ESOS hub
3
progress updates after the Phase 4 action plan
Reg 34B(1)
80
working days is the cap on daily penalties
Part 8
Context
ESOS beside SECR and UK SRS
ESOS is a four-yearly energy assessment, not a disclosure in the accounts.
SECR, under SI 2018/1155, is the annual energy and carbon disclosure, with its own size tests; Phase 4 did not align the two.
Listed companies also face the UK Sustainability Reporting Standards, which ask for emissions and climate metrics but impose no energy audit.
The family hub for UK SRS, uksrs.org.uk, holds the fact base this site is checked against, and its ESOS Phase 4 guide is the companion to this one.
Where the guidance and the law differ
The Environment Agency’s guidance and the GOV.UK hub are restatements; where they differ from SI 2014/1643, this site follows the Regulations and says so.
Frequently asked
Questions people ask
What is ESOS Phase 4?
The fourth compliance period of the Energy Savings Opportunity Scheme, running from 6 December 2023 to 5 December 2027.
Large undertakings, and the UK groups they belong to, must measure their energy use, audit their significant consumption or cover it with ISO 50001, have the assessment signed off and notify the Environment Agency by 5 December 2027.
What is the ESOS Phase 4 deadline?
5 December 2027, the compliance date.
It is generated by regulation 4 of the ESOS Regulations 2014, which ends each compliance period on 5 December four years after the last.
SI 2026/701 did not change it.
Who qualifies for ESOS Phase 4?
An undertaking that on 31 December 2026 employs at least 250 people, or has an annual turnover in excess of £44 million and an annual balance sheet total in excess of £38 million.
Both money limbs must be exceeded.
If any UK undertaking in a group qualifies, the whole UK group participates.
What changed in ESOS Phase 4?
SI 2026/701, in force 22 July 2026, removed Display Energy Certificates and Green Deal Assessments as compliance routes, made ISO 50001 covering total or significant consumption stand in for the audit, required the ESOS report to state energy savings achieved and review the previous action plan, added a third progress update, standardised estimates in kWh, widened the insolvency exclusion and gave lead assessors a personal duty to notify their approval body.
The qualification thresholds did not change.
What are the ESOS Phase 4 penalties?
Five civil penalties in Part 8 of the Regulations.
Failing to notify: £5,000 plus £500 per working day, capped at 80 working days.
Failing to undertake an ESOS assessment: £50,000 or a lesser amount, plus the same daily penalty.
Failing to keep records: £5,000 plus audit costs.
Failing to comply with a notice: £5,000 plus the daily penalty.
A false or misleading statement: £50,000 or a lesser amount.
All carry publication.
Is there a penalty for a late ESOS action plan?
No. None of the five offences in Part 8 attaches to the action plan or progress update duties, so the gap is in the Regulations themselves.
The Environment Agency publishes a failure to submit, and an enforcement notice requiring a plan could itself be enforced.
Does ESOS Phase 4 still allow DECs?
No. Display Energy Certificates and Green Deal Assessments were removed as compliance routes by SI 2026/701.
Their data can still feed an ESOS report, for example in an energy intensity ratio, but they cannot replace the audit.
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.
Checked against 17 sources fromlegislation.gov.ukEnvironment AgencyEnvironment Agency / GOV.UKBSI
- legislation.gov.ukThe Energy Savings Opportunity Scheme Regulations 2014 (SI 2014/1643)
The scheme itself. The consolidated text does not yet show the 2026 amendments.
- legislation.gov.ukThe Energy Savings Opportunity Scheme (Amendment) Regulations 2026 (SI 2026/701), in force 22 July 2026
Every Phase 4 change: routes, savings reporting, the action plan review, the third progress update.
- legislation.gov.ukSI 2026/701 — Explanatory Note
The government’s own summary of what the 2026 amendments do.
- legislation.gov.ukThe Energy Savings Opportunity Scheme (Amendment) Regulations 2023 (SI 2023/1182)
Raised the significant-consumption floor from 90% to 95% and added the 40,000 kWh limb.
- legislation.gov.ukSI 2014/1643 regulation 4 — compliance periods, qualification and compliance dates
Generates 6 Dec 2023 – 5 Dec 2027, 31 Dec 2026 and 5 Dec 2027.
- legislation.gov.ukSI 2014/1643 Schedule 1 — the large undertaking test and amounts A and B
At least 250 employees, or turnover in excess of £44m and balance sheet in excess of £38m.
- legislation.gov.ukSI 2014/1643 regulation 25 — significant energy consumption
Not less than 95% of total energy consumption, by units or by spend.
- legislation.gov.ukSI 2014/1643 regulation 25C — energy intensity ratios
One ratio for each organisational purpose.
- legislation.gov.ukSI 2014/1643 regulation 33A — zero energy consumption
Inserted by SI 2026/701: deemed compliance, but a notification is still made.
- legislation.gov.ukSI 2014/1643 Part 6A — action plans and progress updates
Regulations 34A and 34B.
- legislation.gov.ukSI 2014/1643 regulation 34B — progress updates
Three progress updates for periods ending on or after 5 December 2027.
- legislation.gov.ukSI 2014/1643 Part 8 — civil penalties (regulations 39–47)
Five offences; none attaches to action plans or progress updates.
- Environment AgencyHow to comply with the Energy Savings Opportunity Scheme (ESOS) phase 4 (30 July 2026)
The regulator’s guidance; a restatement of the Regulations, never the master.
- Environment Agency / GOV.UKEnergy savings opportunity scheme (ESOS): find out if you qualify and how to comply (updated 2 September 2026)
The GOV.UK hub, now a Phase 4 page, and the approved lead assessor register list.
- Environment AgencyEnforcement and sanctions policy, Annex 2 — civil penalties for climate change schemes
How penalties are set in practice, including the new-entrant approach at §D2.3.
- BSIPAS 51215 — Energy efficiency assessment: competence of a lead energy assessor
The 2014 edition remains the ESOS competence standard under regulation 12.
- legislation.gov.ukThe Companies (Directors’ Report) and Limited Liability Partnerships (Energy and Carbon Report) Regulations 2018 (SI 2018/1155)
SECR — a separate, annual regime; ESOS thresholds were not aligned with it in Phase 4.
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