Mergers: guidance on jurisdiction and procedure
How the Competition and Markets Authority (CMA) operates the mergers control regime under the Enterprise Act 2002.
Documents
Details
This guidance sets out the procedures used by the CMA in operating the mergers control regime set out in the Enterprise Act 2002, as amended. It also sets out when we will have jurisdiction to review mergers under the Act.
The guidance is for merging parties and their advisers. We also have a simple guide to how mergers are investigated by the CMA.
Changes to the guidance
December 2025
In December 2025, the CMA updated this guidance – and our guidance on merger remedies (CMA87) to reflect procedural changes to merger remedies. We launched a review of our approach to remedies in March 2025, then consulted on changes to our guidance on merger remedies (CMA87).
The changes were designed to embed the ‘4Ps’ framework – pace, predictability, process and proportionality – in our approach to merger remedies and processes.
The revised guidance took effect on 19 December 2025, and applies to merger cases where the formal phase 1 investigation commences on or after 19 December 2025.
October 2025
In October 2025, the CMA updated this guidance to embed its ‘4Ps’ framework into its mergers process. For more information, go to the consultation page.
As part of the October 2025 review, we also updated the Merger Notice template and guidance on the CMA’s mergers intelligence function (CMA56) to reflect those changes.
The revised guidance took effect on 28 October 2025 and applied to mergers:
- where the formal phase 1 investigation commenced on or after 28 October 2025
- referred to phase 2 on or after 28 October 2025
The CMA had started applying the procedural changes described in the revised October 2025 guidance to cases in which the initial draft Merger Notice was submitted after 20 June 2025.
To request previous versions of the guidance, email: general.enquiries@cma.gov.uk
Updates to this page
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Guidance updated to reflect procedural changes to merger remedies.
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Guidance updated to embed the CMA's '4P's framework' in its mergers process
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Updated revised CMA2 guidance published.
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Updated guidance published
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Updated CMA2 guidance to reflect changes to the Enterprise Act 2002 brought about by the National Security and Investment Act 2021.
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Updated CMA2 guidance published.
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Explanatory note added in reference to the Enterprise Act 2002 (Specification of additional section 58 consideration) Order 2020, which adds a further public interest consideration to section 58 of the Enterprise Act 2002.
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Added Water mergers explanatory note
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First published.