The ESOS Phase 4 deadline
The ESOS Phase 4 deadline is 5 December 2027.
This is the final date for submitting your compliance notification to the Environment Agency3, and the full route to that notification is set out in the ESOS Phase 4 compliance guide.
Missing the notification deadline is a failure to notify under reg 43, which carries a fixed penalty of up to £5,000 plus £500 for each working day the failure continues (capped at 80 working days), alongside publication of the breach.
Other ESOS offences carry higher maxima — including £50,000, with downward discretion, for failing to undertake the ESOS assessment itself (reg 45) — as set out in SI 2014/1643 Part 8.
ESOS Phase 4 key dates and timeline
Understanding all ESOS Phase 4 dates ensures timely compliance:
| ESOS Phase 4 dates | Date | What happens |
|---|---|---|
| Phase 4 starts | 6 Dec 2023 | Compliance period begins |
| Data collection | From Dec 2023 | Start gathering energy data |
| Qualification date | 31 Dec 2026 | Determines who qualifies |
| Audit window | 2026-2027 | Conduct energy audits |
| Notification deadline | 5 Dec 2027 | Submit to Environment Agency |
These ESOS Phase 4 dates are fixed in The Energy Savings Opportunity Scheme Regulations1.
Phase 5 will follow immediately, running from 6 December 2027 to 5 December 2031, as confirmed in the ESOS Phase 4 changes guidance4.
ESOS Phase 4 qualification date
The ESOS Phase 4 qualification date is 31 December 2026.
On this date, your organisation qualifies if it meets any of these criteria:
| Qualification test | Threshold |
|---|---|
| Employees | 250 or more |
| Annual turnover | In excess of £44 million |
| Balance sheet total | In excess of £38 million |
You qualify if you have 250+ employees OR exceed BOTH financial thresholds on the ESOS Phase 4 qualification date.
For how these ESOS thresholds interact with part-year accounts and group structures, see the wider qualification guide.
Group undertakings aggregate their numbers — if the group qualifies, all UK entities must participate.
ESOS Phase 4 requirements
The ESOS Phase 4 requirements build on previous phases with additional obligations:
Alternatively, maintain ISO 50001 certification covering your total or significant energy consumption to meet ESOS Phase 4 requirements, as specified in the official ESOS guidance2.
ESOS Phase 4 action plan for meeting the deadline
Your ESOS Phase 4 action plan should follow this timeline:
| Action | When | Who |
|---|---|---|
| Assess qualification status | Now | Finance/HR |
| Nominate responsible officer(s) | Q3 2026 | Board |
| Engage lead assessor | Q4 2026 | Procurement |
| Collect energy data | From Dec 2023 | Facilities |
| Conduct energy audits | Q1-Q2 2027 | Lead assessor |
| Identify savings | Q2-Q3 2027 | Energy team |
| Finalise reports | Q3 2027 | Lead assessor |
| Submit notification | By 5 Dec 2027 | Responsible officer |
This ESOS Phase 4 action plan ensures systematic compliance before the deadline.
Our ESOS consultants provide support at every stage.
Complete ESOS Phase 4 timeline
When is ESOS Phase 4 due? Here's the complete timeline:
Starting early avoids the bottleneck as the ESOS Phase 4 deadline approaches.
The CIBSE ESOS guidance recommends beginning preparations at least 12 months before the deadline.
Frequently asked questions
When is the ESOS Phase 4 deadline?
The ESOS Phase 4 deadline is 5 December 2027. This is the compliance notification deadline by which qualifying organisations must submit their ESOS notification to the Environment Agency. The qualification date is 31 December 2026 — if you qualify on that date, you must comply by the deadline.
What are the key ESOS Phase 4 dates?
ESOS Phase 4 key dates are: compliance period 6 December 2023 to 5 December 2027, qualification date 31 December 2026, and notification deadline 5 December 2027. Organisations qualifying on 31 December 2026 must complete energy audits and notify the Environment Agency by 5 December 2027.
When is ESOS Phase 4 due?
ESOS Phase 4 is due on 5 December 2027. This is when compliance notifications must be submitted to the Environment Agency. However, work should start much earlier — data collection from December 2023, audits through 2026-2027, and lead assessor sign-off before the deadline.
What is the ESOS Phase 4 qualification date?
The ESOS Phase 4 qualification date is 31 December 2026. On this date, if your organisation 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, you qualify for ESOS and must comply by 5 December 2027.
What are the ESOS Phase 4 requirements?
ESOS Phase 4 requirements include: measuring total energy consumption, conducting energy audits covering 95% of energy use (or maintaining ISO 50001), identifying energy-saving opportunities, having an approved lead assessor carry out or review the audit, obtaining sign-off from your responsible officer(s), and submitting notification to the Environment Agency by 5 December 2027.
What should be in an ESOS Phase 4 action plan?
An ESOS Phase 4 action plan should include: determining qualification status, appointing your responsible officer(s) and lead assessor, collecting energy data from December 2023, conducting audits through 2026-2027, implementing ISO 50001 if using that route, getting lead assessor and responsible officer sign-off, and submitting notification before 5 December 2027.
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