ESOS progress update: what's due on 5th December 2026

If your organisation took part in the Energy Savings Opportunity Scheme, known as ESOS, circle 5th December 2026. GOV.UK says that if you qualified in Phase 3, between 6th December 2019 and 5th December 2023, an annual progress update on the action plan you submitted is due by that date.

ESOS is the mandatory energy assessment for larger UK organisations. Every four years you measure the energy used by your buildings, industrial processes and transport, and identify where you could save. You then set out, in an action plan, what you intend to do. The Phase 3 guidance confirms this is the second progress update, and the last Phase 3 deadline.

What you need to send

The Phase 4 guidance, which GOV.UK points you to for this update, asks you to set out:

• which energy-saving measures you have put in place since your last notification, including any that were not on the original plan
• whether each measure in the plan was done by the date you set
• which measures you have not done by that date
• an estimate of the energy those measures have saved, or will save, over the 12 months to 5th December 2026, and how you worked the figure out

A board-level director or equivalent must sign it off. You submit it through MESOS, the online ESOS system. The Environment Agency publishes the updates. If you have not yet submitted an action plan, GOV.UK says you should contact the Environment Agency.

What it means for you

ESOS asks you to plan and report, not to carry out every measure. It does require an honest account of progress, and that account will be public. Dig out the action plan, check what has happened on site, and get a director lined up to review it.

Also check whether you will be in Phase 4. Qualification is tested on 31st December 2026. A large undertaking is one that employs 250 or more people, or has turnover above £44 million and a balance sheet above £38 million. If you qualify, the notification of compliance is due by 5th December 2027.

If you would like a plain-English look at whether the 5th December update applies to you, or help gathering what it needs, I am happy to have a quick, no-obligation chat.