ACER updates its REMIT Manual and FAQs to report inside information

ACER has updated Annex VII of its Manual of Procedures and related FAQs on how to report ‘inside information’ under REMIT. The aim is to further harmonise the disclosure of inside information by providing additional guidance and improve overall data quality of inside information.

What is ‘inside information’ and why does it matter?

The Regulation on Wholesale Energy Market Integrity and Transparency (REMIT) is the EU-wide framework that aims to prevent wholesale energy market abuse and support fair competition.

Under REMIT, information is considered ‘inside information’ if it is:

• precise in nature;
• not yet public;
• directly or indirectly related to wholesale energy products; and
• likely to significantly affect wholesale energy prices if made public.

REMIT requires companies to disclose inside information (such as planned power outages for maintenance, or disruptions to transmission or gas storage), so that all players have the same information at the same time. This helps energy market transparency and integrity.

ACER’s REMIT Manual of Procedures provides guidance on how to report data, including inside information.

What’s new in the Manual?

The update focuses on Annex VII of the Manual (concerning inside information) and introduces clarifications and improvements, including:

• clearer terminology;
• updates to urgent market messages (related to the public disclosure and reporting of inside information);
• guidance on the disclosure of overlapping unavailability events; and
• revised definition of the affected asset code. 

Five of the six updates clarify existing guidance, while the remaining one introduces a change to enhance data quality and surveillance activities. Key improvements include: 

• Message ID (data field 1): Clarification of key terms such as “urgent market messages” (UMMs), "UMM Thread ID" and "version number", to help users better identify and track messages.
• Event status (data field 2): Clearer guidance on how to report the status of an event (e.g. whether an outage is ongoing or resolved), including the principle that published information should remain unchanged and updates should be published as a new version.
• Type of information (data field 3): Clarification on how to classify unavailability events (such as outages or maintenance), while remaining consistent with the Gas Transparency Regulation (EU) 2024/1789.
• Unavailable and available capacity (data fields 9 & 10): Improved guidance on reporting overlapping events, by extending the FAQ 5.1.9 in the Manual and including an example to provide clarification.  
• Affected asset or unit EIC code (data field 17): This field becomes mandatory (both at guidance and schema level), meaning market participants must always identify which asset is affected by the event. Additionally, EIC codes for substations can be reported.

This update is based on the reporting requirements under the current Implementing Regulation (2014) and represents a step towards the development of future inside information reporting under the revised REMIT Regulation (2024). 

Next steps

Market participants have nine months to implement these changes and comply with the new version of the guidance (i.e. by December 2026).

See all updated documents on ACER REMIT Portal.

Coming soon

• ACER public consultation on a new guideline on REMIT transaction reporting. 
• ACER and European Commission webinar: New rules for energy market integrity and transparency (23 April 2026).
• ACER and European Commission annual REMIT workshop (11 June 2026).