Guidance
Information for advisers
Information and guidance for people who advise businesses on competition and consumer issues.
Advising a business on merger investigations
Information about the UK’s merger regime and how the CMA works, and guidance on how to begin a merger.
Before a merger investigation
| Mergers - the CMA’s jurisdiction and procedure: CMA2 | The CMA’s procedures for operating the merger control regime |
| Mergers: how they are investigated | How the CMA investigates mergers, including processes, timelines and possible outcomes |
| Mergers charter: how to work with the CMA on a merger investigation | How the CMA engages with businesses and advisors during merger investigations |
| Information for businesses involved in a merger investigation | Includes information for advisors |
Beginning a merger investigation
| How to notify the CMA of a merger | What you need to give to the CMA to start a merger investigation |
| Merger notice forms | Use these forms to notify the CMA of an anticipated or completed merger |
| Merger fees payment information | Fees for mergers investigations, and how to pay them |
Stay informed
Advising a business on consumer protection and market issues
| Unfair commercial practices: CMA207 | What’s prohibited under the law on unfair business-to-consumer trading |
| Fake reviews: CMA208 | How businesses should comply with consumer protection law on consumer reviews |
| Consumer protection: enforcement guidance (CMA58) | The CMA’s consumer protection role and approach to consumer law |
Get emails about our consumer protection guidance.
Get emails about our markets work.
Advising a business on anti-trust and cartel investigations and how to apply for leniency
Guidance on how to apply for leniency and our work on cartels.
| Competition Act 98 guidance: CMA investigations and procedures | CMA investigation procedures and prosecutions, and how we apply competition law |
| Cartels: come forward and apply for leniency | How to confess a cartel and the CMA’s leniency programme |
| Leniency and no-action applications in cartel cases | How the leniency process works, and when people are immune from criminal prosecution |
Get emails about our work to stop cartels, and guidance around Competition Act cases.
The CMA’s Subsidy Advice Unit and Office for the Internal Market
Find out about the CMA’s Subsidy Advice Unit.
Find out about the CMA’s Office for the Internal Market.
How the CMA works with businesses
The CMA’s 4Ps – pace, predictability, proportionality, and process – support growth, investment and business confidence:
- pace: streamlining our approach
- predictability: clarifying our remit
- proportionality: getting to the right outcomes while minimising burden on business
- process: more direct engagement with businesses
Read our blog post on the 4Ps.
Updates to this page
Published 10 June 2025