ESOS progress report: what goes in it

The last round is already public, and it does not read well

On 5 June 2026 the Environment Agency published the phase 3 action plans and the first phase 3 progress updates as open data[6].

Nobody appears to have read them, so here is what they say.

One organisation in five that published an action plan did not file a first progress update against it.

That is 20.6% of the register, and it is visible to anyone who downloads the file.

Of the 5,549 updates carrying a readable submission date, 80.6% arrived in the final thirty days and 11.2% arrived after the deadline had passed.

Computed from the Environment Agency’s published phase 3 datasets, released 5 June 2026[6]. Method and cross-tabulations are set out in the record below.

Regulation 34B(3) requires three things, and they are not equal

This is the checklist almost nobody publishes, and it is short enough to publish.

The wording of 34B(3)(b) is worth reading twice: has been, or will be achieved.

A progress update is therefore prospective as well as retrospective, which is why a measure installed in month eleven can still carry a full twelve-month figure.

If you are looking for a fill-in form rather than the statutory contents, the ESOS templates page collects what the Environment Agency has published, and the ESOS action plan page covers the document this one reports against.

Regulation 34B(3), ESOS Regulations 2014[2].

Three questions per measure, and one of them is uncomfortable

Regulation 34B(3)(a) breaks into three sub-paragraphs, and they are asked of every measure in the plan.

In the published phase 3 filings, 896 measures — 12.3% of everything explicitly marked implemented — were implemented late against the filer’s own plan date.

A further 12,665 measures were reported as not implemented at the first update at all, which is 41.6% of every measure row on the register.

Not all of those are overdue: an action plan may set an implementation date years out, and the Environment Agency’s own worked example does exactly that.

You may also add measures that were never in the plan, and 1,919 rows did.

Regulation 34B(3)(a)[2]; counts from the published phase 3 progress updates[6].

The number is for twelve months, and that is the trap

The estimate in 34B(3)(b) is denominated over “the relevant reporting period”, and 34B(8) defines that as the window the update itself falls in — a single twelve-month period.

Your action plan’s estimate is not.

Regulation 34A(3)(a)(iv) asks the plan for the total energy savings expected during the relevant compliance period, which is four years.

So the two documents ask for numbers denominated over periods that differ by a factor of four, and nothing in either regulation tells you to divide.

The Environment Agency is explicit that the twelve-month framing governs: savings estimates cover only the twelve-month period regardless of whether the measure was implemented before or during it[5].

Regulations 34B(3)(b) and 34B(8)[2]; regulation 34A(3)(a)(iv)[3]; phase 4 guidance § 14.2[5].

You must declare which of three sources your number came from

Regulation 34B(4) does not accept free text. It requires the responsible undertaking to identify whether the estimate is based on one of three named things.

The Environment Agency’s guidance describes route (a) more broadly than the regulation does, as “data from the ESOS audit or alternative compliance route”[5].

The regulation itself points only at regulation 27(1)(d)(vi), which is an energy-audit provision[2].

Where the two differ, the regulation is the instrument that binds.

Regulation 34B(4)[2]; regulation 27(1)(d)(vi)[4]; phase 4 guidance § 14.2[5].

Route (c) adds a duty most filers do not notice

If your estimate rests on “another reasonable estimation method”, regulation 34B(5) requires two further records.

A brief description of the method used to estimate the reduction.

And the reason for using that method, recorded in the evidence pack.

The second one is easy to miss because it is a reason, not a calculation, and because it lives in a document nobody submits.

In the published phase 3 filings, 1,667 of 5,609 responsible officers confirmed that their evidence pack records the method and the reasons for it.

The remaining 3,942 did not need to, because they were not on route (c).

Regulation 34B(5)[2]; responsible officer confirmations from the published phase 3 progress updates[6].

What each method actually produces for the same measure

Set a measure’s four-year saving and pick a route. The panel shows the twelve-month figure each one produces, and what the published filings did.

Routes from regulation 34B(4)[2]. Distribution computed on the 7,301 measures explicitly marked implemented in the published phase 3 progress updates[6] — see the note on blanks. Not legal advice.

436 organisations reported a four-year total as a twelve-month figure

Of the 3,011 implemented measures whose estimate came from the action plan, the median filer divided by almost exactly four.

The median ratio of the reported twelve-month figure to the plan’s four-year total is 0.250, and 60.4% came in at 0.30 or below.

So most people apportion, correctly, without being told to.

But 436 measures — 14.5% — carried the four-year number across unchanged, and 124 measures — 4.1% — reported more saving in twelve months than the whole four-year plan estimate.

None of that is a penalty question, because there is no penalty here.

It is a signature question: a director has confirmed, to the best of their knowledge, that the undertaking complied with regulation 34B(1) to (5).

Computed on the 3,011 implemented measures declaring route 34B(4)(b)[6].

The published record, as it stands today

Every mark is a real filing. Switch between what was filed, when it arrived, and what happened to the measures inside it.

Environment Agency, published phase 3 action plans and first progress updates, released 5 June 2026[6].

Filing early loses you savings you cannot get back

The Environment Agency says you may notify at any time in the twelve-month window, and then advises you not to.

Its reason is that an early filing leaves out energy savings from measures implemented between your notification date and the deadline[5].

Those measures are not lost — the next update picks them up, because each update counts measures implemented since the last one was notified.

Their savings are a different matter, because the next update’s estimate is denominated over the next twelve-month window, not the tail of this one.

In the published phase 3 filings, 451 organisations — 8.1% — filed more than thirty days early.

The Environment Agency’s own advice is to file near the deadline, which also lets you report on actual data rather than estimates.

Phase 4 guidance § 14 and § 14.1[5]; filing dates from the published phase 3 data[6].

Each update measures only from the last one

Regulation 34B(8) defines the “relevant event” each update measures from, and it is not the action plan every time.

Two consequences follow, and neither is obvious from the form.

The updates are increments, not a running total, so nothing is restated and the three documents only make sense read together.

And the method you declare in update one is the method your later updates get compared against, because a reader lining up three filings is comparing three numbers that were supposed to be produced the same way.

Regulation 34B(8)[2]; regulation 34A(6)[3]; SI 2026/701 regulation 28[1].

Which twelve-month windows are yours?

Choose the compliance period your notification of compliance related to. The windows are computed from the anniversary arithmetic in regulations 34B(1) and 34A(10), not from a lookup table.

That distinction matters, because the statute defines windows and the published milestone table is a rendering of them.

Windows computed from regulation 34B(1)(a), (b) and (c) against regulation 34A(10)’s definition of the relevant compliance period[2][3], with 34B(1)(c) as inserted by SI 2026/701 regulation 28[1]. Not legal advice.

Phase 4 carries three progress updates, not two

SI 2026/701 regulation 28 inserted a third window into regulation 34B(1) for compliance periods ending on or after 5 December 2027.

Applied to a phase 4 notification, the arithmetic produces deadlines of 5 December 2029, 5 December 2030 and 5 December 2031, which is the set published on the ESOS deadlines page along with the mechanism behind it.

Those three dates are named here once and owned there.

What belongs on this page is what changes inside the document as a result.

A third update means a third estimate, on a third twelve-month window, produced by a method that has to stand next to the two before it.

SI 2026/701 regulation 28[1]; phase 4 guidance § 14 and § 14.4[5].

Does phase 3 get a third update too?

This is unresolved, we do not know the answer, and we are setting out the reasoning rather than a date.

Regulation 34A(10) defines the “relevant compliance period” as the compliance period following the one your notification related to.

For a phase 3 notification, that is 6 December 2023 to 5 December 2027.

Regulation 34B(1)(c) applies “for compliance periods ending on or after 5th December 2027”.

On one reading, the period being tested is the relevant compliance period — which ends exactly on 5 December 2027, and the trigger is met.

On the other, it is the compliance period the notification itself related to — which ended on 5 December 2023, and the trigger is not met.

The Environment Agency’s milestone table does not list a third phase 3 update[11], and its phase 4 guidance describes the third update as a new requirement “introduced for action plans for the fourth compliance period”[5].

We are not publishing a third phase 3 deadline, and no date for one appears anywhere on this page, in its tables or in its structured data.

The question is with the Environment Agency and unanswered as at 9 August 2026.

For what phase 3 does carry, including the second update, see ESOS Phase 3.

Regulation 34B(1)(c) as inserted by SI 2026/701 regulation 28[1]; regulation 34A(10)[3]; Environment Agency milestone table[11].

The official guidance contradicts itself twice

Both of these are in the Environment Agency’s phase 4 guidance published on 30 July 2026, and both were checked against the served page on 9 August 2026.

Neither is a trap so much as a reminder that the guidance is a rendering and the regulations are the instrument.

A third divergence sits in the consolidated legislation itself: regulation 34B on legislation.gov.uk still shows only windows (a) and (b), carries an “outstanding changes not yet made” banner, and annotates only the 2023 amending instrument[2].

For 34B(1)(c) the operative text is the one in SI 2026/701 itself[1].

The GOV.UK overview page is a fourth: it still describes an annual progress update “in the 2 subsequent years” and lists only 5 December 2025 and 5 December 2026[7].

That is correct for phase 3 as the regulations stood before the 2026 amendment, and silent on everything since.

For all Phase 4 requirements including the compliance checklist, see ESOS Phase 4.

The same number of directors who signed your compliance notification

Not one director by default, and not necessarily the same people.

The Environment Agency’s guidance is specific: each finalised progress update must be signed off by the same number of directors, or equivalent individuals with management control, as were required to sign the notification of compliance[5].

They are expressly not required to be the same individuals.

Regulation 34B(7) sets out what they are confirming, and it is two things.

Paragraph (1) to (5) is the whole of the duty, including the method under (3)(c) and the evidence-pack records under (5).

A director signing a progress update is therefore confirming something about how the estimate was produced, not only that it was produced.

Regulation 34B(7)[2]; phase 4 guidance § 14.4[5].

It goes through MESOS, like everything else

Regulation 34B(6) requires notification through the Notification System, providing the update itself and the confirmation required by 34B(7).

In practice that is Manage your Energy Savings Opportunity Scheme, the same service that takes your notification of compliance.

The submission must land inside the relevant reporting period.

If you later find that what you submitted was inaccurate, the Environment Agency asks you to email it directly so revised information can be published[5].

There is no correction workflow in the system itself.

Regulation 34B(6)[2]; phase 4 guidance § 14.5[5].

Everything you file becomes public, on a six-month clock

The Environment Agency publishes each progress update within six months of the submission deadline or of receipt, whichever is later[5].

Action plans and progress updates are both published; the ESOS report and the notification of compliance are not[9].

That is why the phase 3 register exists to be analysed at all.

The asymmetry is worth noting: the number is published and the reasoning behind it is not.

So the method label you pick is the only part of your estimation approach a reader ever sees.

Phase 4 guidance § 14.5 and Appendix B[5]; Environment Agency summary of phase 4 updates[9].

There is no fine for missing a progress update

The Environment Agency’s position is explicit: regulators will not take enforcement action or issue a penalty relating to the non-submission of an action plan or progress update[10].

The failure is published by the scheme administrator instead.

Several widely-read consultancy pages get this wrong, opening with fines starting at £5,000 and rising to £50,000.

Those figures are the penalties attaching to a missed notification of compliance, which is a different obligation with a different deadline.

They do not attach to a progress update at all.

What does still carry civil penalties is failing to complete a compliant ESOS assessment and notification by the compliance deadline, which is covered on ESOS penalties.

The practical consequence of a published failure is not regulatory, it is that the register is public, permanent and searchable by anyone assessing you.

Phase 4 guidance § 15[10]; Environment Agency enforcement and sanctions policy[12].

You may report more than you have to — and it is published too

The phase 4 guidance opens a door that is easy to miss: you can volunteer to apply the progress-update requirements to measures implemented before the point the rules make you start[5].

In the first update, that means measures added to the action plan voluntarily which had already been implemented before the plan was notified.

In later updates, it means carrying forward measures you reported on before.

You may also volunteer savings achieved in the twelve months between 6 December 2027 and 5 December 2028 — the year before the first phase 4 reporting period opens.

Anything you volunteer is added to your progress update and published with it.

So volunteering is a disclosure decision rather than a bookkeeping one, and it is worth taking before the first filing rather than during it.

Phase 4 guidance § 14.2.5[5].

The duty follows the undertaking, not the group

If an undertaking files an action plan and then leaves the group before the progress update falls due, the duty does not lapse.

It can be discharged with the previous group by written agreement with that highest parent, or with the new group by written agreement with its highest parent.

Absent an agreement either way, the undertaking must comply on its own behalf[5].

Where a qualifying undertaking is acquired by a non-qualifying group between the compliance date and the action plan deadline, the new highest parent is not required to submit for it.

Any change to the members of the participant should be notified alongside the update itself.

Because action plans and progress updates are published, an undertaking that has left a group can still see the filings it was included in.

Phase 4 guidance § 14.3[5].

Your updates become the evidence base for a review you have not written yet

Phase 4 adds a requirement that changes what a progress update is for.

The ESOS report and notification of compliance must identify measures proposed in the previous action plan that were not implemented, and explain why[9].

That review is written after the updates, and it is written against them.

So the progress updates filed in 2029, 2030 and 2031 are not three annual chores that end when they are submitted.

They are the measure-level record the review will be checked against, and they are already public by the time anyone writes it.

Which means the useful discipline is not “file the update”, it is keep the per-measure evidence in a form that survives four years and two changes of finance director.

Environment Agency summary of ESOS phase 4 updates[9].

Do these in this order, and the first one before the first filing

Nothing here is difficult. It is only expensive to do in the wrong sequence.

The first step is the one that cannot be redone.