Guidance

Mergers guidance on jurisdiction and procedure

Guidance on how the Competition and Markets Authority (CMA) operates the mergers control regime under the Enterprise Act 2002.

• From: Competition and Markets Authority
• Published: 10 January 2014
• Last updated: 28 October 2025 — See all updates

Documents

Mergers: Guidance on the CMA’s jurisdiction and procedure (October 2025 – revised guidance)

PDF, 1.64 MB, 193 pages

Mergers: Guidance on the CMA’s jurisdiction and procedure (January 2025 – revised guidance)

Ref: CMA2

PDF, 1.53 MB, 180 pages

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Mergers: Guidance on the CMA’s jurisdiction and procedure (2024 – revised guidance)

Ref: CMA2

PDF, 1.32 MB, 162 pages

Mergers: Guidance on the CMA’s jurisdiction and procedure (2022 – revised guidance)

PDF, 1.05 MB, 140 pages

Details

This guidance provides advice and general information to companies and their advisers on the procedures used by the Competition and Markets Authority (CMA) in operating the mergers control regime set out in the Enterprise Act 2002, as amended. It also includes guidance on when the CMA will have jurisdiction to review mergers under the Act.

The October 2025 revised guidance reflects updates to embed the CMA’s ‘4Ps’ framework – pace, predictability, process and proportionality – into our mergers process. For more information, go to the consultation page.

We have also updated the Merger Notice template and guidance on the CMA’s mergers intelligence function (CMA56) to reflect these changes.

The October 2025 revised guidance took effect on 28 October 2025 and applies to mergers:

• where the formal phase 1 investigation commences on or after 28 October 2025
• referred to phase 2 on or after 28 October 2025

The CMA has started applying the procedural changes described in the revised guidance to cases in which the initial draft Merger Notice was submitted after 20 June 2025.

Published 10 January 2014

Last updated 28 October 2025 + show all updates

1. 28 October 2025

   Guidance updated to embed the CMA's '4P's framework' in its mergers process

2. 2 January 2025

   Updated revised CMA2 guidance published.

3. 25 April 2024

   Updated guidance published

4. 4 January 2022

   Updated CMA2 guidance to reflect changes to the Enterprise Act 2002 brought about by the National Security and Investment Act 2021.

5. 23 December 2020

   Updated CMA2 guidance published.

6. 23 June 2020

   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.

7. 11 April 2014

   Added Water mergers explanatory note

8. 10 January 2014

   First published.