ESOS deadlines: every date, one lattice
ESOS has never had a single deadline. It has a four-year lattice — five compliance periods since 2014, each with its own qualification date and its own compliance date — and the date that binds you depends on which period your obligations belong to, not on which phase is in the news.
Two dates fall in 2026. Phase 3 action plans reach their second progress update on 5 December 2026, and Phase 4 qualification is a snapshot taken on 31 December 2026. Both are set out in the Environment Agency's Phase 4 guidance, published 30 July 2026.
Find the date that binds you Counts from today · every ESOS date to 2031 · nothing leaves your browserThe ESOS deadlines that actually bind you in 2026
Two, and they are eleven months apart in the calendar but twenty-six days apart in reality.
Everything else people call "the ESOS deadline" is either behind you or more than a year away.
The Phase 4 compliance date is 5 December 2027, the action plan follows on 5 December 2028, and progress updates run to 5 December 2031 [1].
The reason those dates feel confusing is that two compliance periods are live at once, and the scheme has always been built that way.
There is no ESOS deadline.
There is a lattice — and it has been running since 2014.
Five compliance periods, one lattice
The Environment Agency publishes a five-row table of every ESOS compliance period ever set — qualification date, period start, period end, compliance date [1].
No competitor page reproduces it, and it is the single most useful dataset for anyone trying to work out which date applies to them.
Drag or tap a period to see its four dates, and watch where period 3 breaks the pattern.
Every ESOS date follows one rule
Once you have the five periods side by side, the scheme stops looking arbitrary.
Two rules generate almost every date ESOS has ever set, and they have held without exception since 2015.
The compliance date is always 5 December of the compliance period's final year. Period 2 ended 5 December 2019, period 4 ends 5 December 2027, period 5 ends 5 December 2031 [1].
The qualification date is always the 31 December immediately before it — a fixed gap of eleven months and five days. Period 4 qualifies on 31 December 2026 and complies on 5 December 2027 [1].
Periods 2 to 5 are each exactly four years, running 6 December to 5 December.
Period 1 is the only irregular one: it began on 17 July 2014, when the scheme launched, and ran just under seventeen months to 5 December 2015.
That is why the first lane in the lattice above is short — the geometry is the fact, not a decoration.
The ESOS qualification date — 31 December 2026
A qualification date is a snapshot, not an average, and that single property causes most of the confusion about who is in scope.
Your organisation is in scope for Phase 4 if, on 31 December 2026, it meets the large undertaking test: 250 or more UK employees, or annual turnover above £44 million and a balance sheet total above £38 million [1].
The test is applied at UK group level, so one qualifying entity pulls the whole UK group into scope.
The thresholds are stated in sterling in the Phase 4 guidance, and the euro figures that still circulate from the scheme's early years should not be used.
Because it is a snapshot, corporate activity around the date matters more than it looks like it should.
An acquisition completing on 30 December 2026 counts toward qualification; a disposal completing on 30 December 2026 does not.
Shrinking below the thresholds in January 2027 changes nothing — you are in scope for the whole of Phase 4 and you will still be filing progress updates in 2031.
The mirror case is the one organisations get wrong most often: being large for three and a half years of the period and small on 31 December 2026 means you are out of scope, however much energy you used.
Full detail on the scope test, including the group rules and the edge cases, is on the ESOS Phase 4 compliance guide, which owns that subject.
The ESOS compliance date — 5 December 2027
This is the date the industry means when it says "the ESOS deadline", and it is only one line of the lattice.
By 5 December 2027, a qualifying organisation must have completed its ESOS assessment and submitted a notification of compliance to the Environment Agency through MESOS [1].
The notification must be signed off by a responsible officer — a director within section 250 of the Companies Act 2006, or a person exercising management control (regulation 30(2)) — one where the lead assessor is independent of the participant, two in every other case (regulation 30(3) and (4)) [1].
Phase 4 adds two things to that submission that Phase 3 never asked for.
The savings you actually achieved. The report and notification must state the energy savings achieved during the compliance period: each measure implemented, the saving from it in kWh, and its energy-saving category. Only the combined figure across all measures is published, so per-measure numbers stay commercially confidential [4].
A review of your last action plan. The submission must identify the measures you proposed in your Phase 3 action plan and did not implement, and explain why [4].
Those reviews are not published.
Both duties came in with SI 2026/701, which came into force on 22 July 2026.
The practical consequence is that 5 December 2027 is no longer a date you can meet by commissioning an audit in mid-2027 — it now reaches backwards into what you did with the last one.
The ESOS reporting period: which twelve months
A compliance period is four years long, but the energy data you report covers only twelve months of it, and you do not get a free choice of which twelve.
The reference period must be 12 consecutive months that include 31 December 2026 and end on or before 5 December 2027 [1].
Those two constraints pin it tightly: the earliest window opens 1 January 2026 and the latest closes 5 December 2027.
The data must be verifiable where that is reasonably practicable.
In practice most organisations align the reference period to a financial year that straddles the qualification date, because the meter data and the invoices already exist in that shape.
Choosing a window that ends early leaves room to run the audit and get sign-off without compressing both into the last quarter.
Which ESOS deadline binds you, today
Tell it which obligations you carry and it counts the days from today to each date that actually applies to you.
Every count is computed when the page loads, so it is right on the day you read it and not on the day it was written.
Most organisations reading this carry both sets at once: a live Phase 3 action plan with updates still running, and a Phase 4 qualification test arriving in December.
That is not a transitional accident. It is how the lattice is designed, and the next three chapters are about why.
ESOS Phase 3 has not finished
Phase 3's compliance date passed in June 2024, and Phase 3 obligations did not stop there.
The 2023 Amendment Regulations added an action plan and a series of annual progress updates that run on well past the compliance date they belong to [5].
For Phase 3 the action plan was due 5 December 2024, and the two progress updates fall on 5 December 2025 and 5 December 2026 [2].
The second of those is the nearest ESOS deadline in the calendar as this page is published, and it belongs to a phase most coverage has already written off as history.
It covers 6 December 2025 to 5 December 2026 and requires director sign-off.
There is one sequencing constraint that catches late filers: action plans and progress updates cannot be submitted on MESOS until the underlying compliance notification is in place.
An organisation that never filed its Phase 3 notification therefore cannot file the progress update either, and needs to clear the notification first.
Phase 3's status, its late-compliance position and what to do if you have not filed are covered in full on ESOS Phase 3, which owns that subject.
The 182 days when two phases were live at once
This is the structural reason Phase 3 duties run through the Phase 4 period, and it does not appear on any competitor page we could find.
Phase 4's compliance period opened on 6 December 2023 [1].
Phase 3's compliance date, after the extension, fell on 5 June 2024 [2].
So for 182 days, organisations were inside Phase 4's compliance period while still working to a Phase 3 deadline.
The overlap is not an anomaly that has now resolved — it is the shape the whole lattice has, because each period's follow-on duties are longer than the gap to the next period's start.
Phase 3's action plan obligations reach 5 December 2026, which is deep inside Phase 4's period.
Phase 4's own action plan reaches 5 December 2031, which is the last day of period 5.
Every compliance period ESOS has ever run has therefore overlapped the next one, and always will.
That is the answer to the question most readers actually arrive with: not "what is the ESOS deadline", but "why do I keep being told about two different ones".
The only ESOS deadline that has ever moved
Once, and it is still visible in the government's own table.
Phase 3's statutory compliance date was 5 December 2023. The date the Environment Agency now publishes for period 3 is 5 June 2024 — a 183-day extension, granted because the MESOS notification system was not ready.
It is the only date in the entire five-period lattice that is neither a 5 December nor a 31 December.
Has the ESOS deadline moved again?
No, and there is a documented reason to be confident about that answer.
The most recent amending instrument, SI 2026/701, came into force on 22 July 2026 and made substantial changes to Phase 4.
It removed Display Energy Certificates and Green Deal Assessments as compliance routes, added a duty to report savings actually achieved, added an action plan review, widened the insolvency exclusion and added a third progress update [4].
It did not move the compliance date.
The Environment Agency's Phase 4 guidance, published eight days later on 30 July 2026, restates 5 December 2027 [1].
It also left the qualification thresholds alone: the alignment of ESOS and SECR size tests remains deferred to Phase 5 [4].
The 2024 extension was granted for a specific operational reason — a notification system that did not exist when the deadline arrived — and that reason does not apply to Phase 4, because MESOS has been running since 2024.
Searches for a "new ESOS deadline" or an "updated ESOS deadline" are almost always surfacing coverage of the 2024 extension, or of the July 2026 rule changes, rather than a change of date.
The deadlines that come after the compliance date
Notifying is not the end of a compliance period. It is the start of the longest part of it.
Once a compliance notification is filed, an action plan follows twelve months later, and the plan then generates its own annual progress updates [5].
For Phase 4 the ladder runs: notify 5 December 2027, action plan 5 December 2028, then progress updates on 5 December 2029, 2030 and 2031 [1].
The Phase 4 action plan covers 6 December 2027 to 5 December 2031, which is exactly compliance period 5.
Every rung needs director sign-off and every rung is filed through MESOS [1].
Action plans and progress updates are published by the Scheme Administrator, so both the submission and the absence of one are publicly visible.
Content, format, director sign-off and the progress update template are covered on the ESOS action plan guide, which owns that subject.
Every ESOS progress update deadline, both phases
Phase 3 carries two. Phase 4 carries three. They interleave, and 2026 is the year they are closest together.
The third progress update, and one open question
Phase 4 gained a third and final progress update in July 2026, and the published sources do not yet line up perfectly on who else it touches.
Regulation 28 of SI 2026/701 amends regulation 34B to require a final progress update for compliance periods ending on or after 5 December 2027, submitted between the three-year and four-year anniversaries of the start of the relevant compliance period [6].
For Phase 4 that lands on 5 December 2031.
The Environment Agency's own guidance page describes the Phase 4 updates as falling "in 2029 and 2030" — two, not three [1].
That sentence is not in conflict with the regulation; it simply predates or omits the update that SI 2026/701 introduced, and the Agency's own milestone table does list the 2031 date.
We show three, and cite regulation 28 directly at that node, because the instrument is the authority.
Regulation 34B(8) adds a "relevant event" limb reading "in the case of a final progress update, the notification of the further progress update under paragraph (6)", and the cross-reference from 34B(8) into regulation 34A(10) is not visible in the published text of regulation 28.
Read one way, that could give Phase 3 action plans a third progress update in December 2027 that the Environment Agency's milestone table does not list.
Read on its face, it excludes Phase 3 entirely, because Phase 3's compliance period ended on 5 December 2023 and the new duty attaches to periods ending on or after 5 December 2027.
We are not publishing a date for it. GOV.UK's ESOS guidance states the Phase 3 progress update deadlines as 5 December 2025 and 5 December 2026 — two — and until the Environment Agency confirms otherwise, that is what this page shows.
If you hold a Phase 3 action plan and want certainty before December 2027, ask the Environment Agency directly rather than relying on any published timetable, including this one.
ESOS Phase 4 dates in full
The current compliance period, as a date set rather than a guide.
Who qualifies, the 95% coverage rule, audit routes, lead assessors and the full compliance route are on the ESOS Phase 4 compliance guide, which owns that subject.
ESOS Phase 3 dates in full
Still live, because its action plan obligations run into December 2026.
Where Phase 3 stands now, what late filers should do and how the second progress update works in practice are on ESOS Phase 3, which owns that subject.
The ESOS dates that have already passed
Two complete compliance periods sit behind the current one, and they are what establish that the pattern is a pattern.
Period 1 ran 17 July 2014 to 5 December 2015, with a qualification date of 31 December 2014 and a compliance date of 5 December 2015 [1].
It is the only irregular period in the scheme's history, because it began when the regulations came into force rather than on a 6 December.
At just under seventeen months it was less than half the length of every period since.
Period 2 ran 6 December 2015 to 5 December 2019, qualifying on 31 December 2018 and complying on 5 December 2019 [1].
It is the first period to show the rule in its finished form: exactly four years, 6 December to 5 December, with the qualification date on the 31 December before the end.
Neither period carried an action plan or progress updates — those duties arrived with the 2023 Amendment Regulations, which is why Phase 3 is the first phase whose obligations outlive its own compliance date [5].
Anyone searching for "ESOS phase 2 dates" is usually trying to establish that rhythm, and the two rows above are the whole answer.
The next ESOS phase after this one
Period 5 already has published dates, which is unusual and useful.
It runs 6 December 2027 to 5 December 2031, with a qualification date of 31 December 2030 and a compliance date of 5 December 2031 [1].
Those dates are already in the Environment Agency's compliance-period table, so they are not a projection.
Period 5 is also the period the Phase 4 action plan covers, which is why the plan's final progress update and period 5's compliance date fall on the same day.
Two policy questions are explicitly deferred to Phase 5 rather than settled.
Threshold alignment with SECR has not happened: SI 2026/701 did not change the ESOS qualification thresholds, and ESOS and SECR remain distinct regimes with different size tests and different rhythms [4].
Anything published about Phase 5 requirements beyond the four dates above is speculation, and this page does not carry it.
What happens if you miss an ESOS deadline
It depends entirely on which deadline, and the difference is larger than most summaries suggest.
The civil penalty regime attaches to the compliance-date obligations, not to the action plan ladder.
Penalties are set out in regulations 43 to 47 of SI 2014/1643 and restated in the Environment Agency's Phase 4 guidance [1].
Every one of them carries a publication penalty as well as a financial one — the regulator names the organisation, the requirement breached and the amount.
Enforcement process, appeals and how penalties are calculated are on ESOS penalties, which owns that subject.
The ESOS deadlines that carry no penalty at all
Action plans and progress updates are legal requirements with no fine attached, and that surprises people in both directions.
The Environment Agency's Phase 4 guidance states that regulators "will not take enforcement action or issue a penalty relating to the non-submission of an action plan or progress update" [1].
Instead, the Scheme Administrator publishes the failure.
Because action plans and progress updates are published as a matter of course, an absent one is visible on the public register next to every organisation that did file.
That is a reputational exposure rather than a financial one, and it is permanent in a way a paid penalty is not.
It matters most for organisations whose customers, investors or procurement teams check compliance registers, and for anyone whose sustainability reporting elsewhere claims an energy management position the register contradicts.
Do not write, and do not believe, that a missed ESOS action plan carries a fine.
The compliance-date obligations in the previous chapter are where the money is.
What you actually file, and where
Every ESOS deadline in the lattice resolves to a submission through the same system.
Notifications, action plans and progress updates are all filed through MESOS — Manage your ESOS, the Environment Agency's reporting service [1].
All three require sign-off by one or more directors, or equivalent officers [1].
The Phase 4 notification of compliance carries the audit findings, the energy intensity ratios, the savings opportunities identified, the savings actually achieved during the period, and the review of the previous action plan [4].
The sequencing constraint noted earlier applies here in its strongest form: the action plan and progress update forms do not become available in MESOS until the compliance notification for that period has been accepted.
An organisation carrying an unfiled Phase 3 notification therefore has a blocked queue rather than a single missed deadline.
The regulator you file with follows your registered office — the Environment Agency in England, Natural Resources Wales, the Scottish Environment Protection Agency, or the Northern Ireland Environment Agency — with the Secretary of State for DESNZ where activities are wholly or mainly offshore [1].
The Environment Agency is the UK scheme administrator regardless of which body regulates you.
What the notification must contain in detail is covered on the ESOS notification guide.
Working backwards from 5 December 2027
The compliance date is the only fixed point. Everything that has to happen before it is yours to schedule, and most of it has a lead time.
A lead assessor has to be appointed from an approved register, unless ISO 50001 covers your total or significant energy consumption, or you use under 40,000 kWh a year [1].
Twelve months of verifiable energy data has to exist, and the reference period must include 31 December 2026.
Site visits have to be scheduled, and assessor availability tightens sharply in the last two quarters of any compliance period.
Board sign-off has to be obtained, which is a calendar constraint rather than a technical one.
The savings-achieved duty is new and reaches backwards: it needs records of what you implemented from your Phase 3 action plan, in kWh, by category.
Organisations that treat that as a 2027 data-gathering exercise generally find the evidence was never captured.
Five periods. Two rules. One date that ever moved.
ESOS has no single deadline — it has a four-year lattice, and the only two dates that bind you this year are 5 December 2026 if you hold a Phase 3 action plan and 31 December 2026 if you are large enough to be caught by Phase 4.
Knowing the date is the easy half. The Phase 4 submission is the first one that marks your last action plan — and that evidence has to exist before December 2027, not be reconstructed after it.
See what the action plan has to contain Or check whether Phase 4 applies to you at all
UKSRS — independent reference on UK sustainability and energy reporting. Every date on this page is cited to a named primary source.
The complete ESOS date register, 2014 to 2031
Every date the scheme has set or published, in order, with the instrument or guidance that establishes each one.
Dates in the past are marked as such; nothing here is a projection.
No third Phase 3 progress update is listed. GOV.UK states the Phase 3 deadlines as 5 December 2025 and 5 December 2026, and the open question raised by regulation 34B(8) is set out in chapter 14 rather than resolved into a date here.
Where each ESOS subject is covered in full
This page owns the dates and the sequence. Every other ESOS subject has a page that owns it.
ESOS Phase 3
Phase 3 status, late compliance, action plans and the second progress update in practice.
Phase 4ESOS Phase 4 compliance guide
Who qualifies, the 95% coverage rule, audit routes, lead assessors and penalties.
Action plansESOS action plans
What the plan must contain, director sign-off, and the progress update format.
EnforcementESOS penalties
The civil penalty regime, the enforcement process and the appeal route.
Complete guideESOS compliance guidance
The full route from qualification through audit to notification, step by step.
AssessmentESOS energy audits
Audit methodology, scope, site visits and the evidence pack.
ProfessionalESOS lead assessors
Approved registers, qualifications and when you do not need one.
FilingESOS notification
What the notification of compliance must contain and how MESOS submission works.
RequirementsESOS requirements
The full obligation set: coverage, audits, responsible officer sign-off, notification.
ReportingESOS reporting
Reporting requirements, the 95% floor and mandatory site visits.
LegislationESOS legislation
SI 2014/1643 and every amending instrument, with what each one changed.
The schemeThe Energy Savings Opportunity Scheme
What ESOS is, who administers it and how the four-year cycle works.
RoutesISO 50001 vs ESOS
When certification substitutes for an audit, and when it only covers part of you.
IntegrationESOS and UK SRS
How ESOS energy data feeds UK SRS S2 Scope 1 and 2 disclosures.
UK SRSThe UK SRS timeline
How the sustainability reporting calendar sits alongside the ESOS lattice.
ESOS date vocabulary
The words the regulations use, and what each one actually fixes.
Common questions about ESOS deadlines
Direct answers on qualification dates, compliance dates, extensions and what happens when a deadline is missed.
For Phase 3 participants, the next major deadline is 5 December 2026 for Progress Update 2 covering the period 6 December 2025 to 5 December 2026. For all qualifying organisations, the Phase 4 qualification date is 31 December 2026, followed by the Phase 4 notification deadline on 5 December 2027.
ESOS Phase 4 has two key deadlines: 31 December 2026 is the qualification date used to determine which organisations are in scope, and 5 December 2027 is the compliance notification deadline by which audits must be completed and submitted via the MESOS portal, signed off by a responsible officer: a director within section 250 of the Companies Act 2006, or a person exercising management control (regulation 30(2)).
The Phase 3 action plan deadline was 5 December 2024, extended by the Environment Agency to 5 March 2025 due to delays in the MESOS portal. The Phase 4 action plan is due by 5 December 2028 and covers 6 December 2027 to 5 December 2031, followed by three progress updates — 5 December 2029, 5 December 2030 and 5 December 2031.
The Environment Agency can issue compliance, enforcement and civil penalty notices. Maximum penalties are £50,000 initial plus £500 per working day, capped at 80 working days (£40,000), for failure to undertake an ESOS assessment, and £5,000 plus the same daily penalty for failure to notify. Breaches are also published on a public register.
No. The Environment Agency's phase 4 guidance states that regulators will not take enforcement action or issue a penalty relating to the non-submission of an action plan or progress update. The Scheme Administrator publishes the failure instead, so the absence is visible on the public register. Penalties attach to the compliance-date obligations — failure to notify, failure to undertake an energy audit, failure to maintain records, failure to comply with a notice, and false or misleading statements.
A lead assessor is not strictly required for Phase 3 progress updates, but responsible officer sign-off is mandatory: a director within section 250 of the Companies Act 2006, or a person exercising management control (regulation 30(2)). Many organisations choose to involve their lead assessor where implemented actions go beyond the original ESOS recommendations to ensure accurate reporting.
Once. The Phase 3 compliance date moved from its statutory date of 5 December 2023 to 5 June 2024 — a 183-day extension granted because the MESOS notification system was not ready. That is the only ESOS deadline that has ever moved, and it is the only date in the Environment Agency's five-period compliance table that is neither a 5 December nor a 31 December. The Phase 4 compliance date of 5 December 2027 has not moved: SI 2026/701, in force 22 July 2026, changed the compliance routes and added new duties but left the date unchanged.
The Phase 4 qualification date is 31 December 2026. It is a snapshot rather than an average: your organisation's size on that single day determines whether the entire four-year compliance period applies to you. Meeting the large undertaking test that day puts you in scope even if you shrink below the thresholds in January 2027, and being below the thresholds that day keeps you out of scope however much energy you used during the rest of the period. Acquisitions completing before the date count toward qualification; disposals completing before it do not.
Five, and the Environment Agency publishes all of them. Period 1 ran 17 July 2014 to 5 December 2015, period 2 ran 6 December 2015 to 5 December 2019, period 3 ran 6 December 2019 to 5 December 2023, period 4 runs 6 December 2023 to 5 December 2027, and period 5 runs 6 December 2027 to 5 December 2031. Period 1 is the only irregular one, at just under seventeen months, because it began when the regulations came into force rather than on a 6 December.
The reference period must be 12 consecutive months that include 31 December 2026 and end on or before 5 December 2027, using verifiable data where reasonably practicable. Those two constraints mean the earliest possible window opens on 1 January 2026 and the latest closes on 5 December 2027. Most organisations align the reference period to a financial year that straddles the qualification date, because the meter data and invoices already exist in that shape.
Because each compliance period's follow-on duties last longer than the gap to the next period's start. Phase 4's compliance period opened on 6 December 2023 while Phase 3's extended compliance date did not fall until 5 June 2024 — an overlap of 182 days. Phase 3's action plan obligations then run to 5 December 2026, which is deep inside Phase 4's period. Every ESOS compliance period has overlapped the next one, and always will.
Phase 3 requires two, due 5 December 2025 and 5 December 2026 according to GOV.UK's ESOS guidance. Phase 4 requires three, due 5 December 2029, 5 December 2030 and 5 December 2031. The third Phase 4 update is new: regulation 28 of SI 2026/701 amends regulation 34B to require a final progress update for compliance periods ending on or after 5 December 2027. Most published Phase 4 timetables stop at 2030 and are a year short.
Primary references
Every numbered citation on this page resolves here. Every date on this page comes from one of these sources.
Independent reference. This page states deadlines and their sources; it is not legal or compliance advice, and where a date turns on a point of construction — as regulation 34B(8) does — the position is flagged as open rather than resolved.