ESOS · The statutory instrument
The ESOS regulations: SI 2014/1643, Part by Part, as amended
The ESOS regulations are one instrument, the Energy Savings Opportunity Scheme Regulations 2014, and every later ESOS instrument amends it, most recently SI 2026/701 on 22 July 2026.
This page reads the Regulations Part by Part, with every provision, what it does and what last changed it.
It also explains why the published consolidated text cannot yet be read on its own for Phase 4.
The instruments
One instrument, and the instruments that amend it
SI 2014/1643 was made on 24 June 2014 and came into force on 17 July 2014, under section 2(2) of the European Communities Act 1972.
It has never been replaced, so “the ESOS regulations” means that instrument as amended.
The two amendments that reshaped it, SI 2023/1182 and SI 2026/701, were made under sections 254 to 260 and 263 of the Energy Act 2023.
SI 2026/701’s own footnote lists the principal Regulations as amended by SI 2018/1342, SI 2020/711 and SI 2023/1182, adding that “there are other amending instruments but none is relevant”.
The powers and the history of each instrument are on the ESOS legislation page; this page reads what the Regulations now say.
| Instrument | In force | What it did |
|---|---|---|
| SI 2014/1643 | 17 Jul 2014 | The scheme: periods, qualification, assessment, routes, notification, penalties |
| SI 2015/1731 | 26 Oct 2015 | Added “in excess” to the balance-sheet limb; amended the franchise definition |
| SI 2018/1342 | Effect 31 Dec 2020 | Sterling amounts for the size test (itself amended by SI 2020/711) |
| SI 2023/1182 | 29 Nov 2023 | The Phase 3 reforms: 95%, report, ratios, action plans, updates, publication, split compliance date |
| SI 2025/163 | 24 Feb 2025 | Public body redefined through the Procurement Act 2023 |
| SI 2026/701 | 22 Jul 2026 | The Phase 4 reforms |
The architecture
Ten Parts, in the order a participant meets them
| Part | Subject | Regulations | Where to read more |
|---|---|---|---|
| 1 | Citation, interpretation and the review duty | regs 1–3 | Definitions, below |
| 2 | Compliance periods, the administrator, the regulators, the Notification System, publication, lead assessors and registers | regs 4–14 | ESOS phases |
| 3 | Who is in: relevant undertakings, exclusions, participants, the responsible undertaking | regs 15–19; Schs 1–2 | ESOS qualification |
| 4 | The ESOS assessment: total consumption, ratios, the audit, the report, savings achieved, the plan review, the evidence pack | regs 20–28 | ESOS energy audit |
| 5 | Notification and the responsible officer | regs 29–31 | ESOS notification |
| 6 | Deemed compliance: ISO 50001 and zero consumption | regs 33–33A | ISO 50001 vs ESOS |
| 6A | Action plans and progress updates | regs 34A–34B | ESOS action plan |
| 7 | Monitoring and enforcement: compliance notices, inspection, enforcement notices | regs 35–38 | ESOS penalties |
| 8 | Civil penalties | regs 39–47 | ESOS penalties |
| 9 | Appeals and service of documents | regs 48–51 | — |
| 10 | Relevant trust assets | regs 52–53; Sch 5 | — |
Part 4 is where the work is, and since 22 July 2026 it runs through seven chapters: the duty and the assessor (Chapter 1), total consumption (Chapter 2), organisational purposes and ratios (Chapter 2A), the audit (Chapter 3), the report (Chapter 3A), savings achieved and the plan review (Chapter 3B), and the evidence pack (Chapter 4).
Part 6 changed its heading on 22 July 2026 from “Alternative routes to compliance” to “Deemed compliance with Scheme requirements”, and lost regulations 32 and 34.
Provision by provision
Every provision, and what last changed it
Filter by Part, search a word or a regulation number, or show only what SI 2026/701 touched. Each row says which text to cite.
SI 2014/1643 · every provision
70 of 70 provisions
reg 1Citation and commencementPart 1
In force 17 July 2014.
Cite: the revised 2014 text
reg 2InterpretationPart 1
The definitions: undertaking, group undertaking, energy, organisational purpose, kWh and the rest.
- 2023 Definitions inserted, including organisational purpose and energy saving category (SI 2023/1182 reg 3)
- 2026 Inserts "ESOS action plan review" and "previous compliance period"; omits the DEC and Green Deal definitions (SI 2026/701 reg 3)
Cite: the 2014 provision together with SI 2026/701 reg 3
reg 3Duty to reviewPart 1
The Secretary of State reviews the Regulations at intervals of no more than five years and publishes a report.
- 2026 Omits paragraph (2), the comparison with EU Member States (SI 2026/701 reg 4)
Cite: the 2014 provision together with SI 2026/701 reg 4
reg 4Compliance periodsPart 2 Ch 1
The rolling four-year cycle, the qualification date and the compliance date.
- 2023 Paragraph (4) substituted: the split Phase 3 compliance date (SI 2023/1182 reg 4)
Cite: the revised 2014 text
reg 5Scheme administratorPart 2 Ch 2
The Environment Agency.
Cite: the revised 2014 text
reg 6Compliance bodiesPart 2 Ch 2
The regulator for each part of the UK, and the Secretary of State offshore.
Cite: the revised 2014 text
reg 7Co-operation and sharing of informationPart 2 Ch 2
How the administrator and the compliance bodies share information.
Cite: the revised 2014 text
reg 8Notification SystemPart 2 Ch 2
The system responsible undertakings notify through; MESOS is the Environment Agency’s implementation.
- 2023 "ensure the establishment of" substituted in paragraph (1) (SI 2023/1182 reg 5)
Cite: the revised 2014 text
reg 9Provision of information to the Secretary of StatePart 2 Ch 2
What the administrator passes to the Secretary of State.
Cite: the revised 2014 text
reg 10Publication of informationPart 2 Ch 2
What the administrator publishes, and within six months of when.
- 2023 Paragraph (2), the publication clock, and limbs (1)(c)–(e) inserted (SI 2023/1182 reg 6)
- 2026 "Tables A to I" becomes "Tables A to K" (SI 2026/701 reg 5)
Cite: the 2014 provision together with SI 2026/701 reg 5
reg 11Lead assessorsPart 2 Ch 3
A lead assessor is an individual whose name appears on an approved register.
Cite: the revised 2014 text
reg 12Approval bodies and approved registersPart 2 Ch 3
Fixes PAS 51215:2014 as the competence standard and sets the approval bodies’ duties.
Cite: the revised 2014 text
reg 13Reviews of approvalPart 2 Ch 3
Review of an approval body’s approval.
Cite: the revised 2014 text
reg 14AppealsPart 2 Ch 3
Appeals about approval of a register.
Cite: the revised 2014 text
reg 15Relevant undertakingsPart 3 Ch 1
A large undertaking, or a small or medium undertaking in a group with one, on the qualification date.
Cite: the revised 2014 text
reg 16Excluded undertakingsPart 3 Ch 1
Public bodies and undertakings in insolvency proceedings.
- 2026 Insolvency at any point from qualification date to compliance date; new limb (1)(c) for SME group members; insolvency redefined (SI 2026/701 reg 6)
Cite: the 2014 provision together with SI 2026/701 reg 6
reg 17ParticipantsPart 3 Ch 1
Who complies: a single undertaking, or a highest parent group as one participant.
- 2023 Cross-references to Sch 2 paragraphs 7A and 7B inserted (SI 2023/1182 reg 7)
Cite: the revised 2014 text
reg 18Role of the responsible undertakingPart 3 Ch 2
The undertaking responsible for the participant’s compliance.
Cite: the revised 2014 text
reg 19Determination of the responsible undertakingPart 3 Ch 2
The highest parent by default; another group member by written agreement.
- 2023 Cross-references to Sch 2 paragraphs 7A and 7B inserted (SI 2023/1182 reg 8)
Cite: the revised 2014 text
reg 20Duty to carry out ESOS assessmentPart 4 Ch 1
The core duty.
- 2026 Omits ", which includes an energy audit," (SI 2026/701 reg 7)
Cite: the 2014 provision together with SI 2026/701 reg 7
reg 21Role of the lead assessorPart 4 Ch 1
Appoint a lead assessor, hand over the previous evidence pack, have the assessment reviewed.
- 2023 Paragraph (3): no lead assessor under 40,000 kWh (SI 2023/1182 reg 9)
- 2026 Paragraph (2A): the lead assessor’s seven-day notice to their approval body (SI 2026/701 reg 8)
Cite: the 2014 provision together with SI 2026/701 reg 8
reg 21AEstimatesPart 4 Ch 1
When an estimate may be used, and what goes with it.
- 2026 Adds the duty to accompany an estimate with "the data used to make this estimate" (SI 2026/701 reg 9)
Cite: the 2014 provision together with SI 2026/701 reg 9
reg 22Duty to calculate total energy consumptionPart 4 Ch 2
The calculation, the assets held on the qualification date, and the 12-month reference period.
Cite: the revised 2014 text
reg 23Energy consumption – generalPart 4 Ch 2
What counts as energy consumption.
Cite: the revised 2014 text
reg 24Energy consumption – transportPart 4 Ch 2
Transport energy.
Cite: the revised 2014 text
reg 25Identification of areas of significant energy consumptionPart 4 Ch 2
The elective 95% floor, measured in energy units or by spend.
- 2023 90% becomes 95%; paragraphs (3)–(4) inserted (SI 2023/1182 reg 13)
Cite: the revised 2014 text
reg 25AConversion into kWh unitsPart 4 Ch 2
Converting consumption into kWh.
Cite: the revised 2014 text
reg 25BAmount of energy consumption related to organisational purposesPart 4 Ch 2A
Consumption split across the four organisational purposes.
- 2023 Chapter 2A inserted (SI 2023/1182 reg 15)
- 2026 New paragraph (4) (SI 2026/701 reg 10)
Cite: the 2014 provision together with SI 2026/701 reg 10
reg 25CEnergy Intensity RatioPart 4 Ch 2A
At least one ratio per organisational purpose, none where that purpose’s consumption is zero.
- 2023 Chapter 2A inserted (SI 2023/1182 reg 15)
- 2026 New paragraph (4): verifiable data or a reasonable estimate (SI 2026/701 reg 11)
Cite: the 2014 provision together with SI 2026/701 reg 11
reg 26Duty to carry out an energy auditPart 4 Ch 3
Audit the significant consumption, or the total if none is identified.
- 2026 "Subject to Part 6" becomes "Subject to regulations 33(3) and 33A" (SI 2026/701 reg 12)
Cite: the 2014 provision together with SI 2026/701 reg 12
reg 27Identification of energy saving opportunitiesPart 4 Ch 3
What an audit must find, estimate in pounds and kWh, and programme.
- 2023 Paragraph (1)(d) substituted, (1)(e) and the payback formula inserted (SI 2023/1182 reg 17)
- 2026 ", in kWh," inserted in (1)(d)(vi) (SI 2026/701 reg 13)
Cite: the 2014 provision together with SI 2026/701 reg 13
reg 27AESOS ReportPart 4 Ch 3A
The written record of each assessment; not required for periods ending on or before 5 December 2019.
- 2026 Adds the action plan review to the report (SI 2026/701 reg 14)
Cite: the 2014 provision together with SI 2026/701 reg 14
reg 27BEnergy savings since the previous compliance datePart 4 Ch 3A
Omitted; the duty moved, enlarged, to reg 27D.
- 2026 Omitted (SI 2026/701 reg 15)
Cite: the 2014 provision together with SI 2026/701 reg 15
reg 27CDisclosure of information to group undertakingPart 4 Ch 3A
Share the relevant parts of the report with each group undertaking.
- 2026 Amended (SI 2026/701 reg 16)
Cite: the 2014 provision together with SI 2026/701 reg 16
reg 27DEnergy savings since the previous compliance datePart 4 Ch 3B
Savings achieved in kWh, per measure and per organisational purpose.
- 2026 Inserted with Chapter 3B (SI 2026/701 reg 17)
Cite: the 2014 provision together with SI 2026/701 reg 17
reg 27EESOS action plan reviewPart 4 Ch 3B
Measures in the last plan not implemented, and why.
- 2026 Inserted with Chapter 3B (SI 2026/701 reg 17)
Cite: the 2014 provision together with SI 2026/701 reg 17
reg 28Evidence packsPart 4 Ch 4
What the pack holds, and for how long: two further compliance periods.
- 2023 Paragraph (2), the retention period, substituted (SI 2023/1182 reg 19)
- 2026 New contents (1)(a)(iv)–(ix), (j) and (k) (SI 2026/701 reg 18)
Cite: the 2014 provision together with SI 2026/701 reg 18
reg 29Notification of compliancePart 5
What each route notifies, between the qualification date and the compliance date.
- 2026 New limbs (ad), (ae) and (af); paragraph (2) omitted (SI 2026/701 reg 20)
Cite: the 2014 provision together with SI 2026/701 reg 20
reg 30Responsible officersPart 5
One responsible officer where the lead assessor is independent, two in any other case.
- 2023 Paragraph (3A): two officers where reg 21(3) applies (SI 2023/1182 reg 22)
Cite: the revised 2014 text
reg 31Confirmation to be given by responsible officerPart 5
The confirmations the responsible officer gives.
- 2023 Confirmations amended (SI 2023/1182 reg 23)
- 2026 Adds confirmation of any certified energy management system relied on (SI 2026/701 reg 21)
Cite: the 2014 provision together with SI 2026/701 reg 21
reg 32Energy consumption not subject to auditPart 6
Omitted.
- 2026 Omitted (SI 2026/701 reg 23)
Cite: the 2014 provision together with SI 2026/701 reg 23
reg 33Compliance with ISO 50001Part 6
Certification over total or significant consumption stands in for the lead assessor, the audit and the report.
- 2026 New paragraph (2A), the total-or-significant trigger; (3)(a) omitted; (3)(c) now Chapters 3 and 3A (SI 2026/701 reg 24)
Cite: the 2014 provision together with SI 2026/701 reg 24
reg 33AZero energy consumptionPart 6
A participant calculating zero kWh is deemed to have complied with the assessment duties and Part 6A.
- 2026 Inserted (SI 2026/701 reg 25)
Cite: the 2014 provision together with SI 2026/701 reg 25
reg 34Display Energy Certificates and Green Deal AssessmentsPart 6
Omitted: no longer a route.
- 2023 "relevant period" substituted (SI 2023/1182 reg 25)
- 2026 Omitted (SI 2026/701 reg 26)
Cite: the 2014 provision together with SI 2026/701 reg 26
reg 34AESOS action planPart 6A
The plan, its contents in kWh and its notification window.
- 2023 Part 6A inserted (SI 2023/1182 reg 26)
- 2026 kWh; new paragraph (11) for zero-kWh participants (SI 2026/701 reg 27)
Cite: the 2014 provision together with SI 2026/701 reg 27
reg 34BESOS progress updatePart 6A
Annual updates against the plan; three for Phase 4.
- 2023 Part 6A inserted (SI 2023/1182 reg 26)
- 2026 New (1)(c), the final update; kWh; new paragraph (9) (SI 2026/701 reg 28)
Cite: the 2014 provision together with SI 2026/701 reg 28
reg 35Compliance noticesPart 7 Ch 1
The compliance body’s request for information.
Cite: the revised 2014 text
reg 36InspectionPart 7 Ch 1
Powers of inspection.
Cite: the revised 2014 text
reg 37Other informationPart 7 Ch 1
A responsible undertaking must notify the administrator if it becomes aware of a breach.
Cite: the revised 2014 text
reg 38Enforcement noticesPart 7 Ch 2
The notice naming the breach and the steps to remedy it.
Cite: the revised 2014 text
reg 39Penalty noticesPart 8 Ch 1
Service of penalties; daily rates in working days.
Cite: the revised 2014 text
reg 40Effect and recovery of financial penaltyPart 8 Ch 1
Due 60 working days after notice; recoverable as a civil debt.
Cite: the revised 2014 text
reg 41Effect of publication penaltyPart 8 Ch 1
Publication runs for at least a year, and not before the appeal period ends.
Cite: the revised 2014 text
reg 42Discretion in waiving, imposition and modification of civil penaltiesPart 8 Ch 1
Waive, allow time, reduce or modify.
Cite: the revised 2014 text
reg 43Failure to notifyPart 8 Ch 2
£5,000 plus up to £500 a working day, 80 working days at most.
Cite: the revised 2014 text
reg 44Failure to maintain recordsPart 8 Ch 2
£5,000 plus the cost of confirming compliance; no daily penalty.
Cite: the revised 2014 text
reg 45Failure to undertake an energy auditPart 8 Ch 2
£50,000 plus up to £500 a working day, 80 working days at most.
- 2026 Trigger narrowed: "except where regulation 33(3) or 33A applies" (SI 2026/701 reg 29)
Cite: the 2014 provision together with SI 2026/701 reg 29
reg 46Failure to comply with noticePart 8 Ch 2
£5,000 plus up to £500 a working day, 80 working days at most.
Cite: the revised 2014 text
reg 47False or misleading statementPart 8 Ch 2
£50,000; no daily penalty.
Cite: the revised 2014 text
reg 48AppealsPart 9
Grounds: error of fact, wrong in law, unreasonable.
Cite: the revised 2014 text
reg 49Effect of an appealPart 9
An appeal suspends the determination or notice.
Cite: the revised 2014 text
reg 50Determination of an appealPart 9
Cancel, affirm or instruct.
Cite: the revised 2014 text
reg 51Service of documentsPart 9
How notices are served.
- 2026 Paragraph (b) amended (SI 2026/701 reg 30)
Cite: the 2014 provision together with SI 2026/701 reg 30
reg 52Relevant trust assetsPart 10
Which trust assets the modified rules reach.
Cite: the revised 2014 text
reg 53Participants and responsible undertakings in relation to relevant trust assetsPart 10
Who complies for a trust asset.
Cite: the revised 2014 text
Sch 1Relevant undertakingsSchedules
The large undertaking test: at least 250 persons, or turnover over £44m and balance sheet over £38m; headcount and the two-period rule.
Cite: the revised 2014 text
Sch 2Groups of undertakingsSchedules
Aggregation, disaggregation, change of group and franchises.
- 2023 Paragraphs 7A and 7B inserted: group changes after the compliance date (SI 2023/1182 reg 27)
Cite: the revised 2014 text
Sch 3Information to be included in ESOS report, notified and publishedSchedules
Tables A to K: what is reported, notified and published.
- 2026 New Tables J and K; Table G rows 2 and 4 now published (SI 2026/701 reg 31)
Cite: the 2014 provision together with SI 2026/701 reg 31
Sch 4Appeals procedureSchedules
Appeals to the Scottish Ministers and to the Planning Appeals Commission.
Cite: the revised 2014 text
Sch 5Modification of the application of these Regulations in relation to certain relevant trust assetsSchedules
How Parts 3, 4, 6 and 6A and Schedule 3 apply to trust assets.
- 2026 New paragraphs for the 2026 duties (SI 2026/701 reg 32)
Cite: the 2014 provision together with SI 2026/701 reg 32
Headings from the legislation.gov.uk contents of SI 2014/1643; changes from the F-notes and from SI 2026/701 as made, read 1 October 2026.
Nothing you type is saved.
Three provisions are worth reading in full before any other: regulation 4 for the dates, Schedule 1 for who is in, and regulation 21 for the lead assessor.
The deemed-compliance route in regulation 33 must be read with SI 2026/701 regulation 24 beside it.
Reading the text
The consolidated text is current provision by provision, not as a whole
legislation.gov.uk serves two versions of SI 2014/1643: the instrument as made in 2014, and a revised version with later amendments woven in by its editors.
SI 2026/701 itself exists only as made, because an amending instrument is not consolidated into itself.
On 1 October 2026 the revised SI 2014/1643 was part-way through absorbing SI 2026/701.
Schedule 3, regulation 10, regulation 33A and Part 6A carried the 2026 changes, each with its annotation.
The regulation 4 page listed more than twenty SI 2026/701 effects as “yet to be applied”, including the whole of Chapter 3B, regulation 21(2A) and regulation 33(2A).
Regulation 27A’s page showed the pre-2026 text — still citing regulation 27B and the Display Energy Certificate route — under a banner saying there were “no known outstanding effects”.
So neither the revised text nor its banners can be read alone for a Phase 4 point.
The rule that follows is short: for any provision SI 2026/701 touched, cite the 2014 provision with the amending regulation of SI 2026/701, and check the effects register on the day.
For the 2014 starting point, the as-made text still shows the euro thresholds and four routes; quote the revised text for the sterling amounts.
Defined terms
The words the Regulations define
Regulation 2(1) defines the terms the rest of the instrument depends on, and several definitions point onwards to a Schedule or another regulation.
“Undertaking” and “group undertaking” are borrowed from the Companies Act 2006.
“Participant” is whoever complies: a single relevant undertaking, or a group complying together.
“Organisational purpose” has four limbs — transport, an industrial process, buildings, and any other purpose — and a ratio is needed for each that has consumption.
The “Notification System” is the statutory name for what the Environment Agency runs as MESOS; the word MESOS appears nowhere in the instrument.
SI 2026/701 added “ESOS action plan review” and “previous compliance period” and removed the Display Energy Certificate and Green Deal definitions.
Search the panel for any term to see its meaning and where it is defined.
Defined terms · reg 2(1)
35 of 35 terms
- undertaking reg 2(1); CA 2006 s.1161(1)
- A body corporate or partnership, or an unincorporated association carrying on a trade or business, with or without a view to profit.
- group undertaking reg 2(1); CA 2006 s.1161(5)
- Parent and subsidiary undertakings, and subsidiaries of the same parent, as the Companies Act defines them.
- parent undertaking / subsidiary undertaking reg 2(1); CA 2006 s.1162
- Control by voting rights, the right to appoint or remove a board majority, or dominant influence.
- highest parent reg 17(3)
- A parent undertaking with no parent undertaking that is a relevant undertaking.
- highest parent group reg 17(2)
- Relevant undertakings that are group undertakings of each other with one of them the highest parent of the rest; they comply as one participant unless Schedule 2 applies.
- relevant undertaking reg 15(1)
- On the qualification date, a large undertaking, or a small or medium undertaking that is a group undertaking of one, subject to the exclusions in reg 16.
- large undertaking Sch 1 ¶1
- Employs at least 250 persons, or has turnover in excess of £44 million and a balance sheet total in excess of £38 million.
- participant reg 17(1)
- A relevant undertaking complying on its own behalf, or a group of relevant undertakings complying together.
- responsible undertaking regs 18, 19
- The relevant undertaking responsible for the participant’s compliance: the highest parent by default, another member by written agreement.
- responsible officer reg 30(2)
- A director within section 250 of the Companies Act 2006, or a person exercising management control, nominated to confirm the assessment.
- employee reg 2(1)
- As in section 230(1) of the Employment Rights Act 1996 (Great Britain) or article 3(1) of the Employment Rights (Northern Ireland) Order 1996.
- energy reg 2(1)
- As in Article 2(1) of Directive 2012/27/EU, which reg 2 still cross-refers to.
- energy audit reg 2(1)
- An audit carried out, as part of an ESOS assessment, in accordance with Chapter 3 of Part 4.
- ESOS assessment reg 2(1)
- An assessment carried out in accordance with Part 4.
- energy measurement unit reg 2(1)
- A unit by which the supply or consumption of energy is commonly measured.
- kWh reg 2(1)
- Kilowatt hours.
- organisational purpose reg 2(1)
- Transport, an industrial process, buildings, or any other purpose not falling within those three.
- energy saving category reg 2(1)
- An energy management practice, a behaviour change intervention, training, a control, capital investment, or any other method.
- areas of significant energy consumption reg 25(2)
- Assets held or activities carried on that together account for not less than 95% of total energy consumption, measured in energy units or by energy spend.
- reference period reg 22(5)
- Twelve consecutive months beginning no more than 12 months before the qualification date and ending on or before the compliance date.
- initial compliance period reg 4(1)
- From the coming into force of the Regulations, 17 July 2014, to 5 December 2015.
- subsequent compliance period reg 4(2)
- From the 6 December after the previous period ends to the 5 December four years later.
- qualification date reg 4(3)
- The 31 December immediately before the compliance date; 31 December 2014 for the initial period.
- compliance date reg 4(4)
- The 5 December on which the period ends, except the period from 6 December 2019, which has three.
- lead assessor reg 11
- An individual whose name appears on an approved register.
- approved register / approval body reg 12(4)
- A register the scheme administrator has approved, and the body that keeps it.
- Notification System reg 8(1)
- The system for notifying information under the Regulations. MESOS is the Environment Agency’s name for it.
- evidence pack reg 28(1)
- The records of how the participant complied, kept for at least two further compliance periods.
- ESOS report reg 27A
- The written record of an ESOS assessment, required from the period beginning 6 December 2019.
- ESOS action plan reg 34A(3)
- The measures proposed for the next compliance period, with dates and kWh estimates, or a statement that none is proposed.
- ESOS progress update reg 34B(2)
- A written record of action taken since the relevant event to implement energy efficiency measures.
- ESOS action plan review reg 27E
- The measures in the current action plan not implemented and not expected to be, with the reasons.
- Inserted into reg 2(1) by SI 2026/701 reg 3.
- display energy certificate / qualifying Green Deal assessment former reg 34(4)
- Former compliance routes.
- Definitions omitted by SI 2026/701 reg 3(b); reg 34 omitted by reg 26.
- offshore undertaking reg 2(1)
- An undertaking whose activities consist wholly or mainly of offshore activities; its compliance body is the Secretary of State.
- working day reg 2(1)
- Any day other than a Saturday, a Sunday, Christmas Day, Good Friday or a bank holiday.
SI 2014/1643 reg 2(1) and the provisions it points to, read 1 October 2026.
Nothing you type is saved.
22 July 2026
What SI 2026/701 changed, by its own regulation number
SI 2026/701’s regulation numbers are not the numbers it changes: its regulation 23 omits regulation 32 of the 2014 Regulations.
Read both columns.
| SI 2026/701 | Changes in SI 2014/1643 | Effect |
|---|---|---|
| reg 3 | reg 2(1) | Defines “ESOS action plan review” and “previous compliance period”; omits the DEC and Green Deal definitions |
| reg 4 | reg 3(2) | Omits the review duty’s second paragraph |
| reg 5 | reg 10(1)(c) | Publication extends to Tables A to K |
| reg 6 | reg 16 | Insolvency at any point to the compliance date; SME members of an insolvent group; insolvency redefined |
| reg 7 | reg 20 | The assessment duty no longer says it “includes an energy audit” |
| reg 8 | reg 21(2A) | The lead assessor notifies their approval body within seven days |
| reg 9 | reg 21A(1) | An estimate must come with the data used to make it |
| regs 10–11 | regs 25B, 25C | Zero-kWh participants excluded; ratio factors on verifiable data or a reasonable estimate |
| regs 12–13 | regs 26(1), 27(1)(d)(vi) | Audit duty subject to regs 33(3) and 33A; savings in kWh |
| reg 14 | reg 27A | Report adds the plan review; none for Phase 4 on the reg 33(3) or 33A routes |
| regs 15, 17 | regs 27B, 27D, 27E | 27B omitted; new Chapter 3B: savings achieved per measure, and the plan review |
| reg 18 | reg 28(1) | Evidence pack adds ratios, kWh conversion, the report, 27D workings, plan, updates, estimate data and the review |
| regs 19–21 | Part 5; regs 29, 31 | New notification limbs (ad)–(af); officer confirms any certified system relied on |
| regs 22–26 | Part 6; regs 32–34 | Heading changed; regs 32 and 34 omitted; ISO 50001 over total or significant; new reg 33A |
| regs 27–28 | regs 34A, 34B | kWh; zero-kWh carve-outs; a final progress update |
| reg 29 | reg 45(1) | The audit-failure penalty does not reach the reg 33(3) or 33A routes |
| reg 30 | reg 51(b) | Where a notice is served: the address reference now points to Table A |
| regs 31–32 | Schs 3, 5 | Tables J and K; Table G rows 2 and 4 published; trust-asset modifications |
SI 2026/701 left regulation 4, regulation 15, Schedule 1 and every penalty amount unchanged, and contains no net zero provision.
Its only change to Part 8 is regulation 29, which narrows when the regulation 45 penalty applies.
A correction slip of 3 July 2026 corrects its Explanatory Note only, and records that no full impact assessment was produced.
29 November 2023
What SI 2023/1182 did, which is most of today’s scheme
The 2023 amendments came into force on 29 November 2023, a week before Phase 3’s original compliance date.
They substituted regulation 4(4), splitting Phase 3’s compliance date by purpose; the split is set out on the ESOS phases page.
They raised the significant-consumption floor in regulation 25(2) from 90% to 95%, inserted Chapter 2A on organisational purposes and energy intensity ratios, and Chapter 3A on the ESOS report.
They added regulation 21(3), removing the lead assessor below 40,000 kWh, and regulation 30(3A), requiring two responsible officers in that case.
They required representative site visits and a record of how each audit was carried out, in regulation 26(3A) and (9).
They inserted Part 6A, the action plan and progress updates, and regulation 10(2), the six-month publication clock.
They substituted Schedule 3, the report, notification and publication tables, and added change-of-group rules for the action plan period in Schedule 2.
The ESOS action plan and progress report pages take Part 6A in depth.
Regulations 5 and 6
Who administers ESOS: the statutory names
Regulation 5 makes the Environment Agency the scheme administrator, and regulation 6 names a compliance body for each part of the UK.
The guidance uses the operating names — Natural Resources Wales, the Northern Ireland Environment Agency — while the instrument uses the statutory ones, and a citation to the Regulations should use the latter.
The compliance body follows the responsible undertaking’s registered office.
The Department for Energy Security and Net Zero owns ESOS policy, which the Environment Agency’s guidance states; no provision of the Regulations says so.
How the regulators work in practice is on the Energy Savings Opportunity Scheme page.
| Where | Compliance body named in reg 6(1) |
|---|---|
| England | The scheme administrator (the Environment Agency, reg 5) |
| Northern Ireland | The Chief Inspector under the NI industrial emissions regulations 2013 |
| Scotland | The Scottish Environment Protection Agency |
| Wales | The Natural Resources Body for Wales |
| Offshore | The Secretary of State |
Part 8
The penalties are in Part 8, not regulation 29
| Regulation | Breach | Maximum |
|---|---|---|
| 43 | Failure to notify | £5,000, plus up to £500 a working day for up to 80 working days |
| 44 | Failure to maintain records | £5,000, plus the cost of confirming compliance |
| 45 | Failure to undertake an energy audit (not on the reg 33(3) or 33A routes) | £50,000 or such lesser amount as the body determines, plus up to £500 a working day for up to 80 working days |
| 46 | Failure to comply with a compliance, enforcement or penalty notice | £5,000, plus up to £500 a working day for up to 80 working days |
| 47 | False or misleading statement | £50,000 or such lesser amount as the body determines |
Regulations 39 to 42 are the machinery: penalty notices, payment within 60 working days, publication for at least a year, and the regulator’s discretion to waive or reduce.
Regulation 29 sits in Part 5 and is the duty to notify compliance.
No provision of Part 8 names the action plan or the progress updates.
How the Environment Agency sets an actual figure is on the ESOS penalties page.
Where duties lift
Four provisions that reduce or remove a duty
Regulation 21(3) removes the lead assessor where total consumption is less than 40,000 kWh.
Regulation 33, read with SI 2026/701 regulation 24, deems the lead assessor, audit and report done where ISO 50001 covers all total or all significant consumption, and gives partial relief for partial coverage.
Regulation 33A deems the assessment duties and Part 6A done where total consumption is zero.
Regulation 16 excludes public bodies and, since 22 July 2026, undertakings in insolvency proceedings at any point from the qualification date to the compliance date.
In each of the first three cases a notification is still owed; the fourth takes the undertaking out of the scheme.
Each is worked through on the ESOS exemptions page.
The Schedules
Five Schedules, and what each holds
| Schedule | Subject | Amended by |
|---|---|---|
| 1 | Relevant undertakings: the large undertaking test, the amounts, the figures used, headcount, the two-period rule | SI 2015/1731; SI 2018/1342 |
| 2 | Groups: aggregation, disaggregation, change of group, franchises, determinations | SI 2015/1731; SI 2023/1182 |
| 3 | Information in the ESOS report, notified and published, Tables A to K | Substituted by SI 2023/1182; amended by SI 2026/701 |
| 4 | Appeals procedure | — |
| 5 | Modifications for relevant trust assets | SI 2026/701 reg 32 |
Schedule 3 is the practical checklist for a notification, and the ESOS reporting page shows every row of it with what is published.
Citing it
How to cite ESOS law so that it stays right
Cite the instrument and the provision together: “SI 2014/1643, Schedule 1 paragraph 1(a)” can be checked, “the ESOS regulations” cannot.
Say which text you read, as made or revised, and for anything SI 2026/701 touched, cite its amending regulation too.
Use the instrument’s words when citing it — responsible officer, approval body, Notification System, seven days — and the guidance’s words only when citing the guidance.
Quote the revised text for the sterling amounts, never the as-made Schedule 1.
Prefer the instrument to the guidance where they differ: the Environment Agency’s Phase 4 guidance says, for example, that the 2026 amendment revised the compliance deadline, which it did not.
The Phase 4 compliance guide applies these rules duty by duty, and the ESOS deadlines page does the same for every date.
“The penalties are in regulation 29” — they are in Part 8.
“SI 2026/701 changed the thresholds” — Schedule 1 is untouched.
“SECR threshold alignment comes in Phase 5” — the change did not go ahead for Phase 4, and no Phase 5 commitment has been published.
“ISO 50001 exempts you from the ESOS assessment” — it never discharges regulation 20 or the notification.
Around the Regulations
Review, guidance and neighbouring regimes
Regulation 3 requires the Secretary of State to review the Regulations; the second post-implementation review, published in July 2025, recommended keeping them with no major changes.
The regulator’s reading is the Phase 4 guidance of 30 July 2026 and the GOV.UK ESOS page rewritten on 2 September 2026.
The qualification amounts came from SI 2018/1342, and the Phase 4 changes are set out in the contents of SI 2026/701.
Where ESOS sits beside other regimes is covered on the ESOS vs SECR page, with SECR’s own law on the SECR requirements page, and on the ESOS and UK SRS page, with the climate standard on the UK SRS S2 page.
The assessor’s role under regulation 21 is set out on the ESOS lead assessor page, the audit on the ESOS energy audit page, and what comes next on the ESOS Phase 5 page.
Whether an organisation is in at all is on the ESOS qualification page, and the deadlines on the deadlines page.
Check yourself
Six statements about the Regulations
Each answer names the provision it turns on.
Every statement here has appeared, in its false form, in published material about ESOS.
The Part 8 text and regulation 6 settle two of them on their own.
True or false?
01Regulation 29 sets the ESOS penalties.
02SI 2026/701 changed the £44 million and £38 million amounts.
03Regulation 28 is about the evidence pack.
04The regulation 27B savings duty was repealed outright.
05The Regulations call the Northern Ireland regulator the Northern Ireland Environment Agency.
06SI 2026/701 added no new offence.
6 statements.
Pick an answer to see the provision behind it.
Answers rest on the provisions named beside each one.
Nothing you pick is saved.
Frequently asked
The ESOS regulations, answered
What are the ESOS regulations?
The Energy Savings Opportunity Scheme Regulations 2014 (SI 2014/1643), made on 24 June 2014 and in force from 17 July 2014.
Every later ESOS instrument amends them; the most significant are SI 2023/1182, in force 29 November 2023, and SI 2026/701, in force 22 July 2026.
There is no separate ESOS Act.
What did the ESOS Amendment Regulations 2026 change?
SI 2026/701 removed Display Energy Certificates and Green Deal Assessments as routes, let ISO 50001 over total or significant consumption stand in for the lead assessor, audit and report, added a zero-consumption route, required savings achieved to be estimated per measure in kWh and a review of the last action plan, added a seven-day notice by the lead assessor, a third progress update, kWh throughout, a wider insolvency exclusion, and new Schedule 3 Tables J and K. It did not change the qualification test, the compliance dates or any penalty amount.
Is the legislation.gov.uk text of the ESOS Regulations up to date?
Only partly, and provision by provision.
On 1 October 2026 some SI 2026/701 changes were applied, such as Schedule 3, regulation 10 and Part 6A, while others were listed as yet to be applied, and at least one provision page, regulation 27A, showed the pre-2026 text under a “no known outstanding effects” banner.
For any provision SI 2026/701 touched, read the 2014 provision with the amending regulation of SI 2026/701 beside it.
Which regulation sets the ESOS penalties?
Part 8 of SI 2014/1643: regulations 39 to 42 are the machinery and regulations 43 to 47 the five breaches and their maxima.
Regulation 29 is the duty to notify compliance, not a penalty provision.
Which regulation contains the ESOS qualification test?
Schedule 1, reached through regulation 15(2).
Paragraph 1 defines a large undertaking, paragraph 1A sets the £44 million and £38 million amounts, and paragraphs 4 to 11 say which figures are used and how employees are counted.
Who is the ESOS regulator under the Regulations?
Regulation 5 makes the Environment Agency the scheme administrator, and regulation 6 names the compliance bodies: the scheme administrator for England, the Chief Inspector under the Northern Ireland industrial emissions regulations for Northern Ireland, the Scottish Environment Protection Agency, the Natural Resources Body for Wales, and the Secretary of State for offshore undertakings.
What power were the ESOS regulations made under?
The 2014 Regulations were made under section 2(2) of the European Communities Act 1972.
The 2023 and 2026 amendments were made under sections 254 to 260 and 263 of the Energy Act 2023, which treats the 2014 scheme as established under that Act.
Does the word “phase” appear in the ESOS regulations?
The Regulations define compliance periods in regulation 4; “Phase 1” to “Phase 5” is the Environment Agency’s vocabulary for those periods.
The dates come from the regulation 4 formula.
What does Schedule 3 to the ESOS Regulations do?
It lists, table by table, the information that goes in the ESOS report, is notified to the scheme administrator, and is published.
SI 2026/701 added Tables J and K and changed what Table G publishes.
Are the ESOS regulations being reviewed?
Regulation 3 requires periodic review.
The second post-implementation review, published by DESNZ in July 2025, recommended keeping the Regulations with no major changes.
The Modernising corporate reporting consultation says DESNZ intends to consult on SECR and ESOS later in 2026.
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
The principal Regulations, with the amendments the editors have applied.
- legislation.gov.ukThe Energy Savings Opportunity Scheme Regulations 2014 — as made
The 2014 text: euro thresholds, four routes, no report or action plan.
- legislation.gov.ukChanges affecting SI 2014/1643
The effects register: which amendments are applied and which are not.
- legislation.gov.ukThe Energy Savings Opportunity Scheme (Amendment) Regulations 2026 (SI 2026/701), as made
All 32 regulations of the Phase 4 amendment, read in full.
- legislation.gov.ukSI 2026/701 — table of contents
The amendment’s structure, regulation by regulation.
- legislation.gov.ukSI 2026/701, regulation 29 — the audit-failure penalty narrowed
The only change SI 2026/701 makes to Part 8.
- legislation.gov.ukThe Energy Savings Opportunity Scheme (Amendment) Regulations 2023 (SI 2023/1182)
The Phase 3 reforms and the split compliance date.
- legislation.gov.ukThe ESOS (Amendment) (EU Exit) Regulations 2018 (SI 2018/1342)
The sterling qualification amounts.
- legislation.gov.ukEnergy Act 2023 (c. 52)
Part 11, the power under which the 2023 and 2026 amendments were made.
- legislation.gov.ukSI 2014/1643, regulation 4 — compliance periods
The rolling formula and the substituted 4(4).
- legislation.gov.ukSI 2014/1643, regulation 6 — compliance bodies
The statutory names of the regulators.
- legislation.gov.ukSI 2014/1643, regulation 21 — the lead assessor
Review, the 40,000 kWh limb and the seven-day notice.
- legislation.gov.ukSI 2014/1643, regulation 33 — ISO 50001
The deemed-compliance route, read with SI 2026/701 reg 24.
- legislation.gov.ukSI 2014/1643, Schedule 1 — relevant undertakings
The large undertaking test.
- legislation.gov.ukSI 2014/1643, Part 8 — civil penalties
Regulations 39 to 47.
- Environment AgencyHow to comply with the Energy Savings Opportunity Scheme (ESOS) phase 4
The regulator’s reading of the amended Regulations.
- GOV.UK (Environment Agency)Energy savings opportunity scheme (ESOS): find out if you qualify and how to comply
The rewritten Phase 4 page, 2 September 2026.
- Department for Energy Security and Net ZeroThe ESOS Regulations 2014 — second post-implementation review (July 2025)
The regulation 3 review: “Keep”, with no major changes.