Formalising the Familiar: What the EU–UK Competition Cooperation Agreement Means for Business

More than five years after Brexit, the UK and the EU now have a dedicated Agreement on cooperation in the application of their respective competition laws (the “Agreement”). Published on 19 October 2026, it sets a formal framework for cooperation between the UK Competition and Markets Authority (“CMA”) and both the European Commission (“Commission”) and the national competition authorities of the EU Member States (“NCAs”). It supplements the UK–EU Trade and Cooperation Agreement (“TCA”), which anticipated it. The Agreement will enter into force on the first day of the second month after both sides confirm approval, which the CMA’s 2026/27 Annual Plan expects in 2026, stating that it “should lead to more effective enforcement of competition law.”

What’s Changed

Brexit dramatically changed how competition law is enforced across Europe: the UK was carved out of the one-stop shop for mergers, and upon leaving the European Competition Network at the end of 2020, the UK lost access to its case allocation and extensive information-sharing mechanisms. Since then, cooperation has been conducted on an informal basis. While the Agreement does not turn back the clock, it signals a clear intention on both sides to work more closely than in recent years.

That said, how much difference it will make in practice remains to be seen, as the CMA and EU authorities already work closely together. For example, in the end-of-life vehicles recycling cartel, the Commission coordinated its investigation with the CMA and both authorities issued their decisions on the same day. Similarly, the CMA opened its ongoing fragrances cartel investigation in March 2023 in consultation with the Commission (as well as the US and Swiss authorities), years before any formal framework existed. Commission Executive Vice-President Teresa Ribera herself described the Agreement as “reinforcing the current good cooperation.”

Under the Agreement, cooperation remains voluntary and each authority retains full discretion. So, the Agreement largely formalises existing practice. But it matters nonetheless: it sets out how the authorities expect to work together, and businesses should factor that into their approach to future cross-border cases as set out below.

What’s In: Broad Coverage of Core Enforcement

Within the traditional pillars of competition enforcement, the Agreement is broad:

• Laws in scope: On both sides, the prohibitions on anticompetitive agreements and abuse of dominance, and merger control; for the UK, also market studies and market investigations, the criminal cartel offence and competition director disqualification. Public interest aspects of UK merger and market investigations are excluded.
• Early warning via notifications: Where an authority considers that an investigation is likely to affect the other side’s important interests, it must tell its counterparts promptly once the first investigative step is made public (in a UK merger review, this is typically when the CMA announces its initial investigation).
• Coordinating investigations: Authorities may align their work on parallel cases, including on information that businesses provide, but can step away from coordination at any time. Each must also take the other’s important interests into account and make all reasonable efforts to accommodate them (“negative comity”).
• Sharing information: Authorities may, but do not have to, share information, including confidential material, where their own laws allow. Confidential information generally needs the written consent of the business that provided it, typically through a waiver letter. Anything shared can be used only for competition enforcement, only as evidence in the same case, and cannot be passed on without the sending authority’s approval. Strict confidentiality rules apply, and personal data can only be used for purposes compatible with why it was originally collected.
• Protection for individuals: Shared information can be used to penalise individuals only if the sending authority could impose similar penalties, or if equivalent rights of defence were respected and the penalty is not imprisonment.

What’s Out: Significant Gaps, Notably Digital

The exclusions are notable: some of the most active and high-profile areas of current enforcement on both sides of the Channel, particularly digital markets, fall outside the Agreement altogether:

• Digital and other regimes: The new UK and EU digital markets regimes, EU rules on foreign subsidies, State aid, and Member States’ own national competition laws are all outside scope.
• UK sector regulators: Only the CMA is covered; regulators with concurrent competition powers (such as the FCA, Ofcom, Ofgem and Ofwat) are not.
• No right to request action, no obligations: Unlike some other EU agreements, one authority cannot formally ask the other to open a case. Nothing obliges an authority to share information, coordinate, or reach the same outcome, and “important interests” is not defined.

How it Works in Practice

Beyond its headline commitments, several features of the Agreement will shape how cooperation operates day to day:

• Direct links with national authorities: This is the first EU agreement of its kind to cover Member State authorities, so the CMA can deal directly with, for example, the German or French competition authorities without going via the Commission. Information received on the EU side may also be shared among EU Member State authorities.
• National law still governs: The Agreement changes no existing law. In the UK, the CMA’s existing rules on disclosure continue to apply: in practice it will usually share information either with the business’s consent (a waiver) or where needed for its own functions, and must exclude confidential information where practicable.
• Limited enforceability: Disputes cannot be taken to the formal UK–EU dispute resolution process;either side can end the Agreement on 60 days’ notice, and it falls away if the wider UK–EU trade agreement ends.
• Scope for future extension: Either Party can trigger a joint review within two years of entry into force “with a view to further developing their cooperation.” Given the current UK Government’s reported wish for a closer relationship with the EU, it would not be surprising if future reviews are used to widen the Agreement’s scope, for example to digital markets, but nothing is guaranteed and any extension would require a fresh round of negotiation and approval.

Key Takeaways for Businesses

For businesses active in both the UK and the EU, the Agreement shape how parallel investigations and merger reviews are run going forward. Businesses may wish to consider the following practical points:

• Assume authorities are talking: Once a UK or EU investigation becomes public, expect counterpart authorities to be informed promptly. The CMA has also said that, particularly in merger control and digital markets, it will consider whether action by international counterparts may address its concerns and will avoid unnecessary duplication where possible. Plan cross-border merger filings and investigation strategy on a joined-up basis.
• Keep submissions consistent: Arguments, evidence and remedy proposals put to the CMA and EU authorities should be aligned, as inconsistencies are more likely to surface.
• Prepare for waiver requests and protect your data: Consent remains key to sharing confidential information. Expect more requests for waivers and consider carefully their scope, the information covered and any conditions, including how personal data and commercially sensitive material will be handled once shared.
• Consider individual exposure: With the UK cartel offence and director disqualification in scope, cartel and leniency strategies should account for how shared information could be used against individuals.
• Do not expect identical outcomes: Closer cooperation may make parallel reviews more predictable and better synchronised, but the CMA and EU authorities can still reach different conclusions, and digital markets regimes sit outside the framework.
• Watch for entry into force and review: Monitor the completion of ratification and the two-year review, which is intended to develop cooperation further and may be the point at which the Agreement’s scope is widened, for example to digital markets.

The Agreement is a timely reminder of the multi-jurisdictional nature of competition law. While the enforcement of large-scale global cartels is somewhat in abeyance, traditional national barriers continue to fall away as markets become increasingly digital and cross-border. Authorities are responding by taking a more joined-up approach, thus seeking to understand the bigger picture and, in some cases, working more efficiently by building on work already done by their counterparts. Businesses should take an equally joined-up approach to their competition strategy across jurisdictions.

Mayer Brown's European Antitrust & Competition team comprises lawyers with a thorough knowledge of EU and UK laws and procedures, as well as extensive experience of dealing with enforcers at national and EU level. Please contact us to discuss any of the issues summarised above in more detail.