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 mergersmerger 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.Act. 

TheThis Octoberguidance 2025reflects the jurisdictional and procedural changes to the mergers regime made by the Digital Markets, Competition and Consumers Act 2024 (DMCCA24) which commenced on 1 January 2025. 

2 January 2025: revised guidance reflectspublished

The updatesrevised guidance takes effect on 1 January 2025 and applies to embedall merger cases subject to the CMA’ssubject ‘4Ps’to frameworkthe –transitional pace,provisions predictability,in processthe Digital Markets, Competition and proportionalityConsumers –Act into2024 our(Commencement mergersNo.1 process.and Savings and Transitional Provisions) Regulations 2024 (SI 2024/1226) summarised below. 

For more information, gosee to the updated mergers guidance consultation page..  

WeThe havefollowing alsoforms and templates will be updated to reflect the Mergerrelevant NoticeDMCC Act changes in due course: 

• template phase 2 remedies form 

• updated andmerger guidancenotice forms 

• updated template waiver 

Any merger that qualifies for reference for a phase 2 investigation is subject to a fee. This is irrespective of whether a reference is made. Further information on the CMA’sfees mergersand intelligencehow functionto (CMA56)pay tothem reflectare thesein changes.the merger fees information document.

Summary of transitional provisions

The Octoberparts of the 2025 revised guidance dealing with the DMCC Act changes related to jurisdiction, ie the increased turnover threshold (paragraphs 4.3, and 4.52 to 4.57), the share of supply test incorporating the new safe harbour threshold (paragraphs 4.58 to 4.71), and the new hybrid test (paragraphs 4.72 to 4.91) will apply to (i) completed mergers where completion took effectplace on 28or Octoberafter 1 January 2025 and applies(ii) toanticipated mergers:

• mergers where the formal phasePhase 1 investigation (ie the start of the 40 working day initial period) commences on or after 281 OctoberJanuary 2025
• 2025. Chapter 4 of the April 2024 guidance will continue to apply to (i) completed cases where completion took place prior to 1 January 2025, (ii) anticipated cases where the formal Phase 1 investigation (ie the start of the 40 working day initial period) commenced prior to 1 January 2025. For the avoidance of doubt, Chapter 4 of the 2024 guidance will also apply to all cases referred to phase 2 prior to 1 January 2025.   

  The parts of the 2025 revised guidance dealing with the new statutory phase 2 fast track process (paragraphs 7.13 to 7.26) will apply to mergers (excluding mergers of water enterprises and mergers of energy networks) where the formal Phase 1 investigation (ie start of the 40 working day initial period) commences on or after 281 OctoberJanuary 2025

The CMAparts hasof startedthe applying2025 revised guidance dealing with the proceduralextension changesof describedthe phase 2 timetable by mutual agreement between the CMA and the merger parties (paragraph 11.70) will apply to mergers (including energy and public interest mergers) referred to Phase 2 on or after 1 January 2025. The extensions explained in the April 2024 guidance (paragraphs 11.69 and 11.70) will continue to apply to all cases referred to Phase 2 prior to 1 January 2025.  

The parts of the 2025 revised guidance dealing with penalties for supplying false or misleading information (paragraphs 9.34 to 9.37) will apply to cases where false or misleading information was provided in whichrelation to a section 109 notice or a section 5 information request issued on or after 1 January 2025. The April 2024 guidance (paragraphs 9.12 and 9.18) will apply to false or misleading information provided in relation to a section 109 notice or a section 5 information request issued prior to 1 January 2025.  

The parts of the initial2025 draftrevised Mergerguidance Noticedealing waswith submittedpenalties for breaches of section 109 notices (paragraphs 9.38 to 9.43) will apply in relation to section 109 notices issued on or after 201 JuneJanuary 2025. The April 2024 guidance (paragraphs 9.11, 9.19, and 11.22) will apply in relation to section 109 notices issued prior to 1 January 2025.