How to Navigate UK–EU Competition Cooperation in 2026: Step‑by‑step for Businesses Facing Cross‑border CMA/EC Investigations

Understanding how to navigate UK–EU competition cooperation in 2026 is now an operational necessity for any business that trades across the Channel. The UK–EU Competition Cooperation Agreement, signed on 25 February 2026, establishes the first dedicated framework for formal enforcement cooperation between the UK’s Competition and Markets Authority (CMA) and the European Commission together with EU Member State national competition authorities (NCAs). For in-house counsel and compliance leads, this means coordinated investigations, parallel information requests, synchronised dawn raids and shared enforcement intelligence, are no longer theoretical but procedurally embedded. This guide sets out the cross‑border competition investigation process from first contact to final decision, with the timelines, document requirements and pitfall warnings that businesses need to act on immediately.

Overview of the Process and Who It Applies To

The Agreement, presented to the UK Parliament on 25 February 2026 as a supplementary agreement to the December 2020 EU–UK Trade and Cooperation Agreement, has a stated objective of enhancing “the effective enforcement” of both EU and UK competition law. In practice, cooperation covers three domains: antitrust and cartel enforcement, merger control and, to a more limited extent, State aid and subsidy control.

CMA coordination with the EC and EU NCAs operates through several mechanisms defined in the Agreement:

• Notification. Each side must notify the other when an enforcement activity may affect the other’s important interests.
• Coordination and liaison. Authorities may coordinate the timing and scope of parallel investigations, including dawn raids.
• Information exchange. The Agreement provides for the exchange of confidential information between authorities, subject to safeguards.
• Case allocation discussions. Where both sides have jurisdiction, they may discuss which authority is better placed to act.

The cases most likely to trigger cooperation are cross‑border cartels, vertical agreements with effects in both UK and EU markets, and mergers with overlapping competitive assessments. Any business with customers, suppliers or competitive interactions spanning the UK and at least one EU Member State should treat this framework as directly relevant to its enforcement risk profile.

Eligibility and Prerequisites: Is Your Business Exposed?

Not every investigation will involve both regulators, but the threshold for coordination is lower than many businesses assume. The question is not whether you are headquartered in the UK or the EU but whether your conduct or transaction affects markets on both sides.

Use the following checklist to assess whether your case is likely to trigger coordination:

• Market overlap. Your products or services are sold in both the UK and one or more EU Member States.
• Multi-jurisdictional conduct. The alleged infringement involves participants, meetings or communications in both territories.
• Merger with parallel filings. A transaction meets both CMA and EC notification thresholds.
• Cross-border victims. Affected customers or competitors are located in both the UK and the EU.
• Leniency or whistleblower reports. A leniency application has been filed with one authority and the conduct also affects the other jurisdiction.

If any of these apply, coordination is probable rather than merely possible.

When to Notify Counsel

Engage external competition counsel the moment you receive a formal information request under section 26 or section 26A of the Competition Act 1998, a European Commission request for information, or any indication that a dawn raid is planned. Early notification is critical because privilege assertions made after documents have been produced are typically ineffective.

Internal Team and Privilege Preparation

Before any disclosure occurs, designate a single point of contact for regulator communications, brief your IT team on document preservation obligations and ensure that all communications with legal advisers about the investigation are clearly marked as privileged. Inconsistency at this stage creates problems that are difficult to correct later.

How to Navigate UK–EU Competition Cooperation 2026: Step‑by‑Step Procedure

The following steps for businesses provide a structured response framework from the point of first contact with a regulator through to the final decision. Each step should be treated as sequential, although in practice steps may overlap during a fast‑moving investigation.

Step 1, Immediate Intake and Assessment (0–48 Hours)

Preserve all documents immediately. Issue a litigation hold notice covering emails, messaging applications, shared drives and personal devices for all individuals connected to the subject matter. Identify the likely jurisdictions by reviewing the legal basis cited in the request, a section 26 notice under the Competition Act 1998 signals CMA jurisdiction, while a Commission request will reference Regulation 1/2003.

Assemble an incident response team comprising in-house counsel, a senior business representative with authority to make decisions, IT security and your external competition lawyers. Restrict access to the relevant document repositories to prevent inadvertent deletion or alteration. Begin drafting a privilege log template that can be populated as documents are reviewed.

Step 2, Initial Liaison and Early Disclosure Decisions (Days 1–7)

Confirm the scope of the investigation with the regulator. Seek clarity on the legal basis for the request, the specific information sought and the deadline for response. Under the Agreement, the CMA and EC may share the fact that parallel investigations are underway; early indications suggest businesses should assume that anything disclosed to one authority could, in principle, be communicated to the other.

Decide whether to offer limited voluntary disclosure or to respond only to compulsory requests. Prepare a short factual chronology, a neutral statement of the relevant commercial events, that can be shared with external counsel and, if appropriate, with the regulator. This chronology should not contain legal analysis or strategic commentary.

Step 3, Formal Document Production and Parallel Requests (Days 7–30+)

Coordinate document production across both jurisdictions. Where both the CMA and the EC have issued requests, negotiate staggered deadlines to avoid overwhelming internal resources. The CMA typically allows businesses to agree reasonable extensions where requests are complex, but this should be sought formally and in writing.

Assert privilege over any documents that qualify for legal professional privilege under UK law. Prepare a privilege log listing each withheld document by date, author, recipient and a brief, non-revealing description of its subject matter. Apply a consistent redaction protocol: redactions should be clearly marked with the legal basis for withholding and a reference to the corresponding privilege log entry.

Where the EC has issued a parallel request, be aware that the scope of legal professional privilege differs between the UK and EU. Under EU law, in-house counsel communications are generally not protected by legal professional privilege, a distinction that can have significant practical consequences when both authorities are involved in the same matter.

Step 4, Interviews, Leniency/Settlement Strategy (Weeks 4–12)

Prepare witnesses before any formal interview. Witnesses should understand the scope of the investigation, the subjects likely to be covered and their right to have counsel present. Ensure consistency between witness statements given to the CMA and any statements or submissions made to the EC, contradictions between parallel proceedings create serious credibility risks.

Evaluate whether a leniency application or settlement is appropriate. A leniency application to one authority does not automatically extend to the other; separate applications must be filed with each. The timing and sequencing of parallel applications is a critical strategic decision that requires specialist advice. Assess the commercial risk of each option, including the impact on civil follow-on damages claims in both jurisdictions.

Step 5, Decision, Remedies, Appeals and Post‑Decision Compliance (Months 3–24)

Analyse the potential outcomes in each jurisdiction. Fines under the CMA regime are calculated as a percentage of relevant UK turnover, while EC fines can reach up to 10 per cent of worldwide group turnover. Remedies may include behavioural commitments, structural divestments or compliance monitoring programmes.

If a decision is adverse, consider the right to appeal, to the Competition Appeal Tribunal in the UK and the General Court of the EU. Post-decision, implement any required compliance programme and update internal competition law training to reflect lessons learned. The likely practical effect of the Agreement is that compliance deficiencies identified by one authority may be communicated to the other, increasing the reputational and enforcement risk of inadequate follow-through.

Required Documents and Information

The following table sets out the categories of documents most commonly requested during coordinated investigations. Businesses should be prepared to locate, review and produce these materials within the timescales specified by the regulators.

Privilege and Legal Professional Privilege Across UK/EU

Under UK law, communications between a client and an independent external lawyer made for the dominant purpose of obtaining legal advice are protected by legal professional privilege. This extends to in-house counsel in the UK. Under EU law, the position is narrower: communications with in-house lawyers are generally not privileged in Commission proceedings. When both regulators are involved, the safest approach is to assume that any document shared with in-house counsel could be demanded by the EC and to channel sensitive legal analysis through external counsel where possible.

Confidentiality and Non‑Disclosure in Information Sharing

The Agreement contains confidentiality protections that restrict how information shared between the CMA and EU authorities may be used. Information received under the Agreement may only be used for the purpose for which it was transmitted. However, businesses should not treat these protections as absolute, they are safeguards between regulators, not a guarantee that disclosed material will remain confidential in all circumstances.

Data Protection and Cross‑Border Data Transfer

Document productions involving personal data must comply with the UK GDPR and, where relevant, the EU GDPR. Transfers of personal data from the EU to the UK benefit from the EU’s adequacy decision, but businesses should verify that their productions do not include special-category data without appropriate safeguards. The ICO provides guidance on international transfers that should be consulted before any cross‑border disclosure.

Investigation Timeline and Key Deadlines

The following timeline maps the typical phases of a coordinated investigation. Actual durations vary depending on complexity, the number of parties and the degree of cooperation between authorities.

Industry observers expect the CMA’s revised decision model, outlined in its 2026 Annual Plan, to accelerate early-phase case assessment. The likely practical effect will be faster initial engagement and shorter windows for businesses to prepare their first substantive response.

Costs, Fees and Tax Considerations

Cross‑border competition investigations carry substantial costs. The following table provides indicative ranges; actual costs depend on the scope and duration of the matter.

Legal costs incurred in defending an investigation are generally tax-deductible as a business expense. Fines imposed by competition regulators are, in most jurisdictions, not tax-deductible. Businesses should confirm the position with their tax advisers in each relevant jurisdiction.

What Changes in 2026: The UK–EU Competition Cooperation Agreement and CMA Reforms

The 2026 landscape differs materially from prior years. Three developments converge to reshape the cross‑border competition investigation process:

• UK–EU Competition Cooperation Agreement. Signed on 25 February 2026 and presented to the UK Parliament the same day, this is a supplementary agreement to the 2020 Trade and Cooperation Agreement. On the EU side, the Council must still approve the Agreement with the consent of the European Parliament. The Agreement formalises notification, coordination and information sharing rules between the CMA and EU authorities, including the European Commission and Member State NCAs, in relation to antitrust, mergers and State aid matters.
• CMA Annual Plan 2026. The CMA’s 2026 plan signals a commitment to stronger international cooperation and an updated decision model designed to accelerate case outcomes. Early indications suggest this will involve streamlined Phase 1 assessments and earlier engagement with parties under investigation.
• Enhanced information sharing. The Agreement permits the exchange of confidential information between authorities, subject to specified safeguards. Industry observers expect this to be the most consequential operational change, it means that documents or data provided to the CMA in response to a UK investigation could, in principle, be shared with the Commission or an NCA investigating related conduct in the EU.

For businesses, these changes mean that a silo approach to regulator engagement, treating the CMA and the EC as separate, unconnected processes, is no longer viable. A coordinated defence strategy across both jurisdictions is essential from day one.

Common Pitfalls and How to Avoid Them

Privilege Traps

• Failing to assert privilege at the point of production. Privilege must be claimed when documents are withheld, not retrospectively. Prepare a privilege log at the start of the document review process and update it continuously.
• Relying on in-house counsel privilege in EC proceedings. Communications with in-house lawyers are not privileged under EU law. Route sensitive legal analysis through external counsel to preserve protection.
• Inconsistent privilege claims across jurisdictions. If a document is disclosed voluntarily to one authority, the privilege claim in the other jurisdiction may be undermined. Maintain a single, unified privilege log covering both proceedings.

Data and eDiscovery Traps

• Inadequate document preservation. A failure to issue a litigation hold within hours of receiving notice can result in the destruction of relevant evidence, even unintentionally through automated deletion policies. Issue the hold immediately and confirm compliance in writing.
• Overlooking messaging platforms. Regulators increasingly request communications from WhatsApp, Signal, Teams and Slack. Ensure preservation extends to all platforms used by relevant individuals, including personal devices where business communications occur.

Communication and PR Traps

• Uncoordinated public statements. Statements made in one jurisdiction can be used against the business in the other. All external communications about the investigation should be cleared through external counsel first.
• Inconsistent witness accounts. Witnesses interviewed by the CMA and the EC must give consistent accounts. Contradictions between parallel proceedings create credibility risks that regulators will exploit. Prepare witnesses centrally and ensure they understand that both sets of interviews form part of a single factual record.

Sources

1. GOV.UK, UK/EU: Agreement regarding Cooperation on the Application of their Respective Competition Laws [MS No.4/2026]
2. European Commission, EU and UK agree to cooperate closely on competition matters
3. European Parliament, Legislative Train: EU‑UK Competition Cooperation Agreement
4. UK Parliament, Written Statement HCWS1364: UK-EU Competition Cooperation Agreement
5. Competition and Markets Authority (CMA)
6. Competition Act 1998, legislation.gov.uk
7. Information Commissioner’s Office (ICO)