Register for your MESOS account to ensure compliance.

Register for your MESOS (Manage your Energy Savings Opportunity) reporting account now to ensure compliance with ESOS Phase 3.

As mentioned in our previous ESOS Phase 3 – Latest Update, the Phase 3 ESOS compliance deadline. which was previously the 5th of December 2023, has been extended to the 5th of June 2024. 

This extension was granted to allow for necessary time for participants to meet the new ESOS Phase 3 requirements, as well as allowing time for the Government to launch their new online notification system Manage Your Energy Savings Opportunity Scheme Reporting’ (MESOS).

As of March 2024, the MESOS system is now live and representatives from the responsible undertaking can create an account for their organisation. However, users cannot yet submit a notification of compliance. An update is scheduled for the end of April 2024, which will allow users to complete their notifications of compliance.

  • Once a relevant organisation administrator (Advanced User) has set up an organisation’s account, they can add additional users onto the account via their email address.
  • After a user has been added onto an organisation’s account, they will receive an email asking them to confirm their account, alongside instructions on how to sign up for a MESOS account (if they have not already done so).
  • Once the user has followed the instructions within this email, their account status shall be updated to ‘Accepted’.
  • It is then the Advanced User’s responsibility to manually change MESOS account MESOS account the user’s account status from ‘Accepted’ to ‘Active’. It is important this final step is completed, otherwise the additional user shall not be able to access the organisation’s account.
  • An individual can be a representative for more than one organisation and added onto multiple MESOS accounts (such as a consultant acting on behalf of an organisation). An external ESOS Lead Assessor can also be added onto an organisation’s account, following the same steps as above.
  • There are two types of users on the MESOS System: Advanced Users and Restricted Users. Only Advanced Users can add additional users onto an organisation’s account.


It is stated within the MESOS guidance, that an external lead assessor should only be added as a ‘Restricted User’ onto an organisation’s account.

The deadline for submitting a notification of compliance is still the 5th of June 2024.

However, as a result of the new Phase 3 requirements and the launch of the new MESOS system, the Environment Agency has stated that if this compliance deadline is not met, no enforcement action shall be taken, providing the following conditions are met:

  1. You have registered for an account on MESOS by the 5th of June 2024, and
  2. You have submitted your notification of compliance by the 6th of August 2024.

If you have any questions regarding the information within this blog, then please contact

For further details on the requirements of ESOS, check out our ‘ESOS Know How’ page.


Bethany Bailey

Carbon Analyst