March 5, 2026

Bridging the Channel: A New Era of EU-UK Competition Enforcement Cooperation

Euan Burrows, Peter Citron, Dr. Michael Engel, Marc Israel, James Killick White & Case LLP + Follow Contact LinkedIn Facebook X Send Embed

The European Commission and the United Kingdom have signed a landmark EU-UK Competition Cooperation Agreement ("Agreement"), establishing the first formal post-Brexit framework for structured cooperation between EU competition authorities (including Member State authorities) and the Competition and Markets Authority ("CMA").

Whilst EU and UK authorities have cooperated informally since Brexit, this Agreement institutionalises notification, coordination and information-sharing mechanisms for antitrust and merger enforcement. Although it does not harmonise substantive law or guarantee aligned outcomes, it marks a significant step towards deeper cross-Channel enforcement coordination.

The Agreement is not yet in force and must be ratified by both the EU and the UK. Whilst no significant obstacles to ratification are anticipated, the exact timeline remains uncertain.

Key Takeaways

• First structured enforcement framework since Brexit: The Agreement formalises cooperation between the European Commission, EU national competition authorities and the CMA in relation to antitrust enforcement and merger control.
• Reciprocal notification obligations: Authorities must notify one another of enforcement activities likely to affect the other’s "important interests" shortly after the first public investigative step.
• Scope for coordinated enforcement activity: Where authorities pursue related matters, they may coordinate enforcement steps if mutually beneficial.
• Negative comity mechanism: Authorities must seek an "appropriate accommodation" where enforcement activity may adversely affect "the important interests" of the other party.
• Information exchange subject to safeguards: Confidential information may be shared where lawful under domestic law. In practice, company waivers will often remain necessary.
• Limited scope: The Agreement applies to competition law and merger control enforcement. It does not extend to regulatory matters (such as technology regulatory matters covered by the EU Digital Markets Act or the UK Digital Markets, Competition and Consumers Act), or the EU Foreign Subsidies Regulation. However, continued informal cooperation on technology regulatory cases can be expected, especially as these are likely to be a key plank of enforcement in the next few years. The Agreement covers only the enforcement of EU and UK competition law and does not extend to the national competition laws of individual EU Member States.

Background

The December 2020 EU-UK Trade and Cooperation Agreement envisaged cooperation in competition matters but did not provide a detailed operational framework. Since Brexit, cooperation between the European Commission and the CMA has largely relied on informal engagement and ad hoc coordination.

In practice, the CMA and the European Commission have demonstrated a capacity for close operational coordination, by conducting dawn raids simultaneously on the same day (as seen, for instance, in the fragrances and construction chemicals sectors), and by issuing separate fining decisions on the same date (as exemplified by enforcement action in the recycling of end-of-life vehicles sector). The two authorities have also discussed potential remedies in parallel merger cases. Close operational coordination has not necessarily led to convergence of outcome.

Core Provisions

The Agreement, signed on 25 February 2026, is a "supplementary agreement" to the December 2020 EU-UK Trade and Cooperation Agreement (which broadly provided for cooperation in competition law matters but expressly contemplated the subsequent conclusion of a dedicated agreement).

The stated aim of the Agreement is “to promote cooperation and coordination in competition matters”. The Agreement 1 includes the following key provisions:

Notification Obligations (Article 3): Where an enforcement activity may affect the "important interests" of the other party, the authority concerned must notify its counterpart promptly after "the first publication of an investigative step". The term "important interests" is undefined in the Agreement and leaves each authority discretion in determining when its important interests have been engaged. Whilst it remains to be seen how the authorities will interpret this provision in practice, it is likely to increase transparency in parallel investigations and merger reviews. Notification following the first public investigative step is a relatively late stage, so, in practice, the authorities can be expected to begin coordinating informally with each other at an even earlier stage.

Coordination of Enforcement Activities (Article 4): Where authorities pursue the same or related enforcement matters, they may agree to coordinate aspects of their activity. The provision is permissive rather than mandatory, preserving discretion on whether and how to coordinate.

Negative Comity (Article 5): If enforcement activity risks adversely affecting the important interests of the other party, authorities must make reasonable efforts to reach an "appropriate accommodation". The Agreement does not contain a positive comity mechanism (i.e. one authority cannot require the other to initiate enforcement action).

Information Sharing and the Consent Requirement (Articles 6 and 7): Competition authorities may share information "to the extent that the sharing of that information is lawful under applicable domestic law, including that on confidentiality and data protection". Written consent from the company which provided confidential information will generally remain necessary unless domestic law permits disclosure without consent, which will rarely be the case. Information shared may be used only for competition law enforcement purposes and, typically, only for the specific proceeding for which it was collected.

Practical Implications for Business

The Agreement will have meaningful practical consequences for companies subject to parallel EU and UK scrutiny.

Parallel Investigations Will Become More Structured: Formal merger control notification obligations increase the likelihood that EU and UK authorities will be aware of each other’s enforcement steps at an early stage. Whilst informal cooperation has already occurred, the new framework makes parallel processes more predictable and potentially more synchronised.

Business should assume a higher probability of aligned requests for information, coordinated investigative steps and closer dialogue between authorities in antitrust and merger cases. However, coordination does not guarantee convergence of substantive conclusions. In mergers, the statutory timeframes are not aligned, but authorities will often seek to coordinate to be able to take steps at similar times. This may lead to one authority asking merging parties to delay notification so that the deadlines for a decision by the different authorities can end up being aligned.

Waiver Strategy Becomes Even More Important: The Agreement preserves the central role of waivers for confidential information exchange. In practice:

• Authorities will often request waivers to facilitate meaningful cooperation.
• Granting waivers may streamline investigations and reduce duplication.
• However, waivers can increase transparency between authorities and potentially narrow room for jurisdiction-specific positioning, especially where there may be a debate as to whether the relevant geographic market is national or wider (say, EEA- or Europe-wide). Parties should be strategic in their approach to waivers, considering the timing of waiver submissions, the scope of information covered, potential implications for remedy discussions and the risks of divergent enforcement approaches.

Consistent Submissions and Internal Alignment Are Critical: Given the likelihood of closer cooperation, inconsistencies in submissions between jurisdictions will be more visible. Business should ensure aligned market definition arguments (where defensible), consistency in economic evidence and data sets, coordinated engagement with authorities and careful management of internal documents and evidence (particularly in antitrust investigations). Parallel teams should operate within a unified cross-border strategy from the outset.

Diverging Outcomes Remain Possible: Despite enhanced cooperation, the Agreement does not harmonise substantive law. The EU and UK operate under distinct legal frameworks and policy priorities. Authorities may still reach different conclusions on market definition, competitive effects, theories of harm, remedies or proportionality of fines. Business should prepare contingency plans for divergent outcomes, including differing remedy packages or procedural timelines.

Timing and Deal Planning Considerations: Whilst greater coordination may improve predictability, it may also affect timelines. For instance, authorities may seek to align review stages and negative comity discussions could introduce additional dialogue. Parallel investigations may require greater resource allocation. Transaction planning should factor in potential cross-Channel coordination dynamics, particularly for complex Phase II merger reviews.

Next Steps

The Agreement must undergo ratification in both jurisdictions. On the EU side, this requires a Council decision to conclude the Agreement and the consent of the European Parliament. The UK must also complete its domestic ratification procedures.

The Agreement provides for a joint review within two years of entry into force, potentially paving the way for further deepening of cooperation.

1 The Agreement has not yet been published in the Official Journal. This analysis of its key provisions is based on the draft text that was included in the European Commission’s proposal for a Council Decision (COM(2025) 232 final), which is which is expected to be identical in all material respects.

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DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.
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