Consultancy support
Specify the analysis, coordination, audit work and handover the engagement includes.
Independent buying guide
ESOS consultants
ESOS consultants can support the assessment and evidence work, but the buying brief should separately identify the registered lead assessor, the reporting organisation’s responsibilities and the handover.
Is an ESOS consultant the same as a lead assessor?
A consultancy can help with data, audits and preparation, while the lead assessor has the appointment and review role in regulation 21.
Define the work before appointing
Lead assessor appointment
Name the individual and verify their entry on an approved register where an appointment is required.
Read the detailed guidance and evidence
Read regulation 21 alongside the Environment Agency’s current register list rather than treating a consultancy brand or professional membership as the individual’s register entry.
What should an ESOS consultancy proposal include?
Ask for a named delivery team, a defined assessment scope, the lead assessor arrangement and a reusable evidence handover.
Appointment briefRequirements and evidence
Module 01 / 04
Scope
Identify the participant, sites, activities and compliance route.
Module 02 / 04
People
Name the lead assessor and the people preparing the audit work.
Module 03 / 04
Outputs
Specify the audit findings, evidence records and review deliverables.
Module 04 / 04
Handover
Agree who completes notifications and retains the final evidence pack.
Read the detailed guidance and evidence
Use the ESOS Phase 4 requirements guide to establish the reporting task before comparing consultancy proposals for it.
Who is responsible for which task?
Write the division of work into the engagement and distinguish contracted support from the roles the Regulations assign.
| Role | Work to make explicit | Provision to check |
|---|---|---|
| Reporting organisation | Provide evidence, arrange the assessment and own the participant notification | Regulations 21, 28 and 29 |
| Consultancy team | Prepare the contracted analysis, records and supporting materials | Deliverables should match regulations 26 and 27 |
| Lead assessor | Review the assessment and perform the assessor notification duty | Regulation 21 |
| Responsible officer | Confirm the assessment through the applicable officer route | Regulation 30 |
How do you check an ESOS lead assessor?
Verify the named individual on a currently approved register and keep a dated record of the check.
Register checkRequirements and evidence
Module 01 / 04
Individual
Ask who will actually hold the lead assessor appointment.
Module 02 / 04
Approved body
Follow the Environment Agency’s current list to the relevant register.
Module 03 / 04
Current entry
Check the person’s listing rather than relying on a company logo.
Module 04 / 04
Continuity
Agree what happens if the named assessor becomes unavailable.
Read the detailed guidance and evidence
Regulation 12 provides the approved-register mechanism, and the official ESOS hub links the approved bodies and their registers.
What should you ask before appointing?
Use evidence from the proposed team and a defined sample deliverable to assess whether the engagement fits the participant.
| Question | Evidence to request | Record in the decision |
|---|---|---|
| Who leads the work? | Named assessor, register entry and role allocation | The individual checked and the date checked |
| How will sites be sampled? | Proposed site coverage and explanation of representativeness | What evidence is needed before the approach is settled |
| What will the audit contain? | A redacted or illustrative output structure | The fields included and any limitations |
| What remains after delivery? | Evidence pack contents and notification responsibilities | Internal owners and unresolved actions |
Does an external assessor mean one officer signs?
Check the statutory independence test rather than assuming that a paid external appointment automatically meets it.
Officer routeRequirements and evidence
Module 01 / 04
Definition
Read the responsible-officer definition in regulation 30(2).
Module 02 / 04
Independence
Check the relationships covered by regulation 30(4).
Module 03 / 04
One officer
The one-officer route applies where the lead assessor is independent under that test.
Module 04 / 04
Other cases
The other route requires two responsible officers, including the specified no-assessor case.
Read the detailed guidance and evidence
Regulation 30 addresses current or recent employment, office, management and shareholding relationships and specified spouse or civil-partner relationships, so the buying brief should request an explicit independence check.
Which officer route should the engagement plan for?
Have the organisation and assessor resolve the applicable route before the final assessment review.
| Situation | Responsible-officer route | Primary provision |
|---|---|---|
| Lead assessor independent under regulation 30(4) | One responsible officer | Regulation 30(3)(a) |
| Other lead assessor cases | Two responsible officers | Regulation 30(3)(b) |
| No appointment under regulation 21(3) | Two responsible officers | Regulation 30(3A) |
What should be settled before requesting a quote?
Establish the likely participant boundary and qualification position, then identify the energy records and sites the proposal must cover.
Scope firstRequirements and evidence
Module 01 / 04
Qualification
Check the size test and the rules for successive accounting periods.
Module 02 / 04
Group
Identify any group relationship that changes the participation position.
Module 03 / 04
Route
Determine whether the assessment uses energy audits or an applicable ISO 50001 route.
Module 04 / 04
Evidence
List available records and gaps before estimating the work.
Read the detailed guidance and evidence
The size test is in Schedule 1, the undertaking rules in regulation 15 and regulation 16, and the ISO route in regulation 33.
Does the participant appear to qualify for Phase 4?
Use this initial qualification and reference-period check to prepare the conversation, then resolve the actual participant boundary and evidence with the appointed team.
Phase 4 check · one undertaking at a time
Figures for the accounting period ending on, or in the 12 months before, 31 December 2026.
Not in scopeOut on these figuresUnder 250 persons, and not over both money limbs. Check the group before relying on this.SI 2014/1643 Sch 1 ¶¶1, 11; reg 15
Your 12-month reference period
Valid: 1 January 2026 to 31 December 2026.
It ends on or before 5 December 2027 and includes 31 December 2026.
SI 2014/1643 reg 22(5); EA Phase 4 guidance §4.4Indicative, not advice.
It tests one undertaking; groups, overseas parents and disaggregation are set out in the section beside it.
Nothing you enter leaves your browser.
Read the detailed guidance and evidence
The size boundaries are at least 250 persons, or both turnover over £44 million and balance sheet total over £38 million, subject to the accounting-period rules in Schedule 1.
The tool also covers the group and exclusion questions and the reference-period rule in regulation 22, and it is not a substitute for documenting the organisation’s actual circumstances.
What should the energy audit deliver?
Specify findings that explain the energy use and evaluate opportunities, with the required costs, savings and implementation information.
Audit findingsRequirements and evidence
Module 01 / 04
Consumption
Analyse energy consumption and energy efficiency.
Module 02 / 04
Opportunities
Identify ways energy efficiency could improve and cost-effective measures.
Module 03 / 04
Evaluation
Record costs, benefits, annual savings and payback information.
Module 04 / 04
Implementation
Include a recommended programme and timescale.
Read the detailed guidance and evidence
Regulation 27 sets the audit-content requirements, including the reasonably-practicable qualification, while regulation 26 addresses audit coverage, data and representative site visits.
How can a participant test the proposed handover?
A fictional multi-site participant can ask the team to explain one proposed measure from its source energy record through to the audit recommendation.
| Fictional exercise | Ask the team to show | Useful acceptance evidence |
|---|---|---|
| Choose one representative site | Why it represents the wider energy use | The recorded site-selection rationale |
| Choose one saving opportunity | The calculation, assumptions and relevant evidence | A reproducible estimate with limitations stated |
| Review implementation | The programme and timescale recommended | A clear separation between audit recommendation and implementation contract |
| Change the internal owner | How a replacement owner finds the records | A navigable evidence pack rather than an unexplained final PDF |
How should ESOS consultant fees be compared?
Compare quotations for the same scope and deliverables, with assumptions and extra-work triggers stated in writing.
Quotation scopeRequirements and evidence
Module 01 / 04
Participant
State the entities, sites, activities and available records.
Module 02 / 04
Audit work
Clarify visits, analysis, sampling and the assessment route.
Module 03 / 04
Review
Include assessor review, corrections and officer coordination.
Module 04 / 04
After delivery
Distinguish evidence handover, notification assistance and later support.
Read the detailed guidance and evidence
This guide does not establish a market-wide ESOS consultancy price, so use a defined scope to compare quotations instead of treating unlike headline fees as equivalent.
What should the contract leave unambiguous?
Agree the practical handover, review and notification tasks before work starts.
| Contract item | Clarify | Acceptance question |
|---|---|---|
| Deliverables | Audit output, supporting records and evidence-pack structure | Can another internal owner understand the assessment? |
| Revisions | What review and correction rounds are included | Who resolves a disputed or missing input? |
| Notification | Who prepares, checks and submits each required notification | Is the participant task distinct from the assessor’s own duty? |
| Later work | Action-plan support, progress updates and implementation advice | Which work needs a separate engagement? |
What must happen after the assessment?
Plan the participant notification and the lead assessor’s separate notification duty as distinct tasks.
Completion recordRequirements and evidence
Module 01 / 04
Participant
Allocate the organisation’s notification preparation and submission.
Module 02 / 04
Assessor
Confirm the lead assessor knows the separate approved-body notification duty.
Module 03 / 04
Officers
Retain the appropriate responsible-officer confirmation.
Module 04 / 04
Evidence
Keep the assessment records and a usable handover.
Read the detailed guidance and evidence
Regulation 29 concerns participant notification, while regulation 21(2A) gives the lead assessor seven days beginning with the day after the participant notification to notify their approved body with the prescribed information.
How can the appointment and assessment be organised?
Use this editorial workflow to coordinate the engagement, while taking the actual Phase 4 dates from the Regulations rather than from this sequence.
- 101
Check participation
Resolve the undertaking and group questions. - 202
Define the engagement
List sites, activities, data and the intended assessment route. - 303
Verify the assessor
Check the named person on an approved register. - 404
Agree the proposal
Record scope, deliverables, assumptions and fees. - 505
Prepare the evidence
Assign owners and resolve missing energy records. - 606
Complete the assessment
Document audit findings and supporting calculations. - 707
Arrange review
Resolve assessor comments and the officer-confirmation route. - 808
Coordinate notifications
Separate participant submission from the assessor’s own notification. - 909
Retain and plan
Hand over the evidence and identify any separately contracted follow-up work.
What should the next step be?
Prepare the participant and energy-data brief before approaching an assessor or consultancy, then compare written proposals against it.
Ready to appointRequirements and evidence
Module 01 / 04
Timing
Check Phase 4 dates before agreeing the delivery programme.
Module 02 / 04
Evidence
Tell bidders what records exist and where gaps remain.
Module 03 / 04
Acceptance
Describe the required audit, review and evidence outputs.
Module 04 / 04
Follow-up
Allocate later actions separately from the completed assessment.
Read the detailed guidance and evidence
Phase 4 has a qualification date of 31 December 2026 and compliance date of 5 December 2027 under regulation 4, and the energy audit guide and action-plan guide explain the related tasks in more detail.
Frequently asked
Questions people ask
Is an ESOS consultant the same as a lead assessor?
A consultancy can provide support, while the lead assessor has the statutory appointment and review role under regulation 21, so verify the named individual and their approved-register entry.
How do I find an approved ESOS lead assessor?
Use the Environment Agency’s current list of approved register bodies and check the proposed individual on the relevant register.
How much do ESOS consultants charge?
Request comparable written quotations covering the participant, sites, data quality, audit approach, review, notification support and handover, since this guide does not establish a market-wide fee.
Does an external lead assessor always mean one responsible officer?
No, because the one-officer route depends on independence under regulation 30(4), with two responsible officers required in the other cases described in regulation 30.
Can ISO 50001 affect the appointment scope?
Yes, but the certification coverage and the requirements addressed by regulation 33 must be checked before defining any residual audit, assessor and notification work.
Who makes the seven-day notification to the approved body?
The lead assessor has the separate regulation 21(2A) duty, which must not be confused with the participant’s regulation 29 notification.
Sources
Primary sources
Primary provisions and official guidance read on 26 October 2026.
Checked against 15 sources fromlegislation.gov.ukEnvironment Agency
- legislation.gov.ukCompliance periods and qualification dates: regulation 4
- legislation.gov.ukApproved lead assessor registers: regulation 12
- legislation.gov.ukQualification: Schedule 1
- legislation.gov.ukRelevant undertakings: regulation 15
- legislation.gov.ukExcluded undertakings: regulation 16
- legislation.gov.ukLead assessor appointment and notification: regulation 21
- legislation.gov.ukTotal energy and reference period: regulation 22
- legislation.gov.ukEnergy audits: regulation 26
- legislation.gov.ukAudit content: regulation 27
- legislation.gov.ukEvidence pack: regulation 28
- legislation.gov.ukParticipant notification: regulation 29
- legislation.gov.ukResponsible officer and independence: regulation 30
- legislation.gov.ukISO 50001 route: regulation 33
- Environment AgencyESOS guidance and approved registers
- Environment AgencyHow to comply with ESOS Phase 4
Continue reading
Read next
Guide
ESOS overview
Place the engagement within the scheme.
Guide
ESOS Phase 4 requirements
Check qualification and timing.
Guide
ESOS energy audits
Read the audit and evidence requirements.
Guide
ISO 50001 and ESOS
Check how certification affects the assessment route.
Guide
ESOS action plans
Separate later planning work from the assessment.