ESOS Thresholds — Who Qualifies for Phase 4

ESOS Phase 4 qualification is assessed at 31 December 2026. Understanding the 250-employee test, the £44m turnover and £38m balance sheet test, group aggregation rules, and ISO 50001 alternative route.

247 days to qualification date31 Dec 2026Phase 4

← Part of our ESOS, SECR and UK SRS guide

The Qualification Date: 31 December 2026

Critical Date: ESOS Phase 4 qualification is assessed at a single point in time — 31 December 2026. Your organisation's status on this specific date determines whether you're in scope for the entire Phase 4 cycle, regardless of changes before or after.

Why 31 December 2026?

Gives organisations 11 months to prepare after qualification is confirmed
Aligns with financial year-end for most UK companies
Allows time for structural changes and corporate reorganisations
Provides certainty for procurement of Lead Assessor services

What Happens After Qualification?

5 December 2026: Progress Update 2 deadline (if applicable from Phase 3)
Throughout 2027: Energy audit must be undertaken with Lead Assessor
5 December 2027: Compliance notification and Action Plan submission
Phase 5: Cycle begins again (dates to be confirmed)

The Three Qualification Tests

Key Principle: You qualify for ESOS Phase 4 if your UK group meets either the employee test or both financial tests at 31 December 2026. Meeting just one financial test is not sufficient.

Employee Test

250+ employees

Scope

Total UK group employment

Calculation

All UK subsidiaries and parent company

Notes

Includes contractors if they work exclusively for the group

Click to learn more

Turnover Test

£44+ million

Scope

Annual turnover (revenue)

Calculation

Most recent annual accounts period

Notes

Must be exceeded in conjunction with balance sheet test

Click to learn more

Balance Sheet Test

£38+ million

Scope

Annual balance sheet total

Calculation

Most recent annual accounts period

Notes

Must be exceeded in conjunction with turnover test

Click to learn more

Qualification Logic — Either/Or

Route 1: Employee Test

You qualify if:

• Your UK group employs 250 or more people
• Regardless of financial thresholds
• Includes all subsidiaries under common control

Route 2: Both Financial Tests

You qualify if:

• Annual turnover exceeds £44 million
• AND annual balance sheet total exceeds £38 million
• Based on most recent annual accounts

Group Aggregation Rules

Critical Principle: If any single UK entity in your group meets the thresholds, the entire UK group becomes subject to ESOS. This applies even if other group companies are individually sub-threshold.

What Counts as a Group?

Parent-subsidiary relationships: Companies where another company holds more than 50% of voting rights
Controlling influence: Where a company can direct operating and financial policies
Common control: Multiple entities under the same ultimate parent company
UK scope only: Only UK-incorporated entities count for ESOS aggregation

The "Responsible Undertaking"

Single entity responsibility: One group company becomes the "responsible undertaking" for ESOS compliance
Group-wide coverage: The responsible undertaking must ensure energy audits cover the entire UK group
Designation flexibility: Groups can choose which entity serves as responsible undertaking
Legal liability: The designated entity bears full legal responsibility for compliance

Recent Acquisitions, Divestments, and Structural Changes

Acquisitions

Companies acquired before 31 December 2026 count toward qualification thresholds.

• Include in employee count
• Add to financial thresholds
• Must be included in energy audit scope
• Historical energy data may be limited

Divestments

Companies sold before 31 December 2026 do not count toward qualification.

• Exclude from employee count
• Remove from financial thresholds
• No audit requirement for divested entities
• May affect overall qualification status

Reorganisations

Internal restructuring may change qualification without affecting the underlying business.

• May create or remove ESOS obligations
• Consider timing relative to 31 Dec 2026
• Legal entity structure affects aggregation
• Seek advice before major changes

ISO 50001 Alternative Route (100% Coverage Requirement)

Complete Alternative to Energy Audit

Organisations can satisfy ESOS requirements through ISO 50001 certified energy management systems instead of undertaking a traditional energy audit, provided they achieve 100% coverage of their total energy consumption.

100% Coverage Requirements

All energy use: Every aspect of your organisation's energy consumption must be covered
All sites: Every UK location where the group operates
All subsidiaries: Every entity within the ESOS-qualifying group
Current certification: ISO 50001 certificates must be valid at compliance deadline

Hybrid Route (ISO 50001 + Audit)

Partial coverage: ISO 50001 covers some but not all energy consumption
Audit remainder: Traditional ESOS audit required for uncovered consumption
Lead Assessor required: For the audit portion of the compliance approach
Combined reporting: Single compliance notification covers both routes

Out-of-Scope Cases

Public sector bodies

Central government, local authorities, NHS trusts, public corporations

Rationale: Separate government energy efficiency initiatives apply

Sub-threshold organisations

Groups that don't meet any of the three qualification tests

Rationale: Regulatory burden proportionate to organisation size

Unincorporated entities

Sole traders, general partnerships (with exceptions)

Rationale: Limited legal structure for regulatory obligations

Dormant companies

Companies with no significant business activity

Rationale: No meaningful energy consumption to assess

What to Do This Quarter If You Think You're In Scope (or Unsure)

Immediate Actions (Next 30 Days)

Group mapping: Identify all UK group companies and their current employee counts
Financial review: Pull latest annual accounts for turnover and balance sheet figures
ISO 50001 audit: Check current energy management certifications and coverage scope
Legal review: Engage legal counsel if group structure changes are being considered

Planning Actions (Next 90 Days)

Lead Assessor research: Begin identifying qualified advisors and obtaining quotes
Energy data audit: Review availability and quality of historical energy consumption data
Budget planning: Allocate budget for ESOS assessment costs
Governance setup: Establish project governance and assign internal responsibility

Don't Wait Until December: If you're likely to qualify, start planning now. The market for Lead Assessor services becomes constrained as the deadline approaches, and energy audits require significant preparation time.

Related ESOS Pages

ESOS Phase 4 Deadline

Timeline and key dates for compliance

Is ESOS Mandatory?

Legal framework and penalties

ESOS vs SECR

How the two regimes compare and overlap

Finding ESOS Consultants

Lead Assessor requirements and procurement

ESOS Assessment Costs

Pricing and budget planning

ESOS, SECR and UK SRS

How the three UK regimes work together

Sources and References

Primary Sources

ESOS Regulations 2014, Regulation 5 (Qualification)ESOS Phase 4 Amendment Regulations 2023 GOV.UK ESOS Guidance ESOS Compliance Guidance, Appendix D

Professional Bodies

Energy Managers Association CIBSE ESOS Lead Assessor Scheme(Professional bodies maintain approved registers of qualified Lead Assessors)