ESOS action plan deadlines and guidance

What an ESOS action plan is

An ESOS action plan is a forward-looking statement of the energy-efficiency measures a participant intends to implement, following its ESOS energy audit. The requirement sits in regulation 34A of the Energy Savings Opportunity Scheme Regulations 2014 (SI 2014/1643), inserted by the ESOS (Amendment) Regulations 2023 (SI 2023/1182).

The action plan converts audit recommendations into commitments.

It states which energy-saving measures the organisation intends to take, and it is followed by annual progress updates reporting delivery against those commitments under regulation 34B (Part 6A, SI 2023/1182).

The detailed requirements are set out in Sections 12–13 of the GOV.UK full ESOS guidance.

Unlike the audit itself, the action plan and its progress updates are published — creating public accountability for the commitments made.

Who must submit an action plan

Every participant that was required to notify compliance for the third compliance period — Phase 3, notification deadline 5 June 2024 — had to submit an action plan.

If your organisation was in scope for Phase 3, the action plan obligation followed automatically.

The test for being an ESOS participant is the "large undertaking" definition: 250 or more UK employees, or annual turnover above £44 million together with a balance sheet total above £38 million (regulation 2(1) of SI 2014/1643, as amended by SI 2023/1182).

Our is ESOS mandatory guide covers qualification in detail, and the Phase 4 thresholds guide covers the 31 December 2026 qualification date.

Action plan deadlines

For the third compliance period, the action plan deadline was 5 December 2024, six months after the extended Phase 3 notification deadline of 5 June 2024.

The plan had to be submitted through the MESOS digital service with board-level director sign-off.

The Environment Agency accepted action plans submitted after the deadline without remedial action until 5 March 2025.

That grace window has now closed — a Phase 3 participant that has still not submitted should engage the Environment Agency proactively rather than wait for enforcement contact.

The deadlines above are set by SI 2014/1643 as amended and summarised in the GOV.UK ESOS guidance (updated 16 February 2026).

The Phase 4 notification deadline of 5 December 2027 is covered in our ESOS compliance guide.

Annual progress updates — 5 December 2025 and 5 December 2026

Regulation 34B of SI 2014/1643 as amended requires annual progress updates against the action plan in the two years following its submission.

For Phase 3 participants, those updates fall due on 5 December 2025 and 5 December 2026.

Each update reports what has actually been delivered against the commitments in the action plan.

Like the action plan itself, progress updates are submitted through MESOS and are made public (Sections 12–13, GOV.UK full guidance).

Board-level sign-off

The action plan must be signed off by a board-level director before submission (GOV.UK ESOS guidance).

This mirrors the board sign-off required for the ESOS assessment itself and puts the organisation's leadership formally behind the published commitments.

Because the commitments are public and will be tested in the Phase 4 assessment, boards should treat sign-off as more than a formality.

Over-committing creates a published record of unmet promises that must later be explained; under-committing is visible to stakeholders reviewing the published plan.

Submitting via MESOS

Action plans and progress updates are submitted through MESOS — the "Manage your ESOS reporting" digital service used for ESOS compliance notifications, operated by the Environment Agency as scheme administrator.

An updated MESOS system is planned for early 2027, alongside the full Phase 4 guidance (GOV.UK ESOS guidance, updated 16 February 2026).

Phase 3 progress updates due on 5 December 2026 use the current system.

Public disclosure

Action plans and progress updates are made public (Sections 12–13, GOV.UK full guidance).

This is a deliberate design feature of the Part 6A framework: the audit stays internal, but the commitments and their delivery record do not.

Publication means customers, investors, and ESG due-diligence teams can compare what your organisation promised with what it reported delivering.

Organisations already preparing energy and emissions disclosure under SECR or UK SRS should align the narratives — an ESOS action plan that contradicts the annual report is an avoidable credibility risk.

What changes in Phase 4

The GOV.UK ESOS guidance (updated 16 February 2026) confirms the Phase 4 changes going ahead, subject to parliamentary time.

Progress against action plan commitments will be included in the ESOS assessment, and an explanation will be required where commitments have not been met.

Phase 4 also removes Display Energy Certificates and Green Deal Assessments as compliance routes — see the energy audit guide for the surviving routes.

The net-zero refocus and the alignment of qualification thresholds with SECR are postponed to Phase 5 (GOV.UK ESOS guidance).

For Phase 4 participants, the action plan cycle repeats after the 5 December 2027 notification deadline, with the Phase 4 action plan due by 5 December 2028 under the Part 6A framework.

Full Phase 4 guidance and the updated MESOS system are planned for early 2027 (GOV.UK).

Penalties for non-compliance

Failure to produce an action plan or its progress updates is a breach of Part 6A of SI 2014/1643 as amended, exposing the responsible undertaking to civil penalties enforced by the Environment Agency (with equivalent regulators in the devolved nations).

Enforcement also carries publication of the non-compliance on the Environment Agency's public register — often the more damaging consequence for organisations subject to investor or supply-chain ESG screening.

The full penalty framework, including the fixed and daily penalty amounts, is set out in our ESOS penalties and enforcement guide.

Organisations behind on any action plan obligation should engage the Environment Agency proactively.

Early engagement and demonstrated good faith consistently produce better enforcement outcomes than waiting to be identified through the EA's compliance monitoring.

Frequently asked questions