Do I Need to Notify the CMA for a Joint Venture? UK Guide for Deal Teams (2026)

Getting the joint venture notification UK question right early can be the difference between a clean, on-schedule closing and a costly retrospective inquiry. This guide is built for deal teams who need a binary answer, notify the Competition and Markets Authority (CMA) or don’t, and the paper trail to stand behind that decision. In 2026, the coming into force of the merger-control changes under the Digital Markets, Competition and Consumers Act 2024 has sharpened the uncertainty around how partial and non-full-function joint ventures are treated, so the safe assumptions of a few years ago should be revisited.

Below you will find a decision framework, the statutory test, a side-by-side comparison table, an operational checklist and template language you can adapt for your internal memo.

For the wider regulatory backdrop, read our UK competition law reform 2026 (context) guide, which sets out the reform programme this JV note sits within.

Executive decision summary, a quick “Do I need to notify?” framework

Most joint venture notification UK decisions reduce to two questions: is the JV treated as a “merger” for UK purposes, and are the jurisdictional thresholds met? If the answer to both is yes, notification (or at least active CMA engagement) belongs at the centre of your deal plan. If the answer is a clear no, you can proceed, but you must document why.

Choose to notify (or engage the CMA) when:

• Full-function JV. The JV will operate as an autonomous economic entity on a lasting basis and the jurisdictional thresholds are met.
• Threshold trigger. The turnover or share-of-supply thresholds under the Enterprise Act 2002 are satisfied.
• Control shift. There is a substantial change in the control of an existing business, or a material overlap in a sensitive market.
• Genuine legal uncertainty. The characterisation is borderline and the deal is strategically valuable, voluntary filing or early CMA advice reduces execution risk.

Choose not to notify (but document the decision) when:

• Non-full-function. The JV does not operate autonomously and the parents do not jointly exercise decisive influence over an independent business.
• Purely contractual cooperation. The arrangement is a supply, distribution or R&D contract with no own legal personality and no lasting change of control.
• No material coordination. There is no meaningful overlap and no realistic competition concern.

Immediate triggers to retain external merger counsel: a full-function JV in a concentrated market; a share-of-supply overlap approaching the statutory 25% threshold; any transaction with public interest sensitivity; or a JV where the internal team cannot reach a confident view on full-function status.

The legal test and jurisdictional thresholds for a joint venture notification UK decision

Statutory basis, the Enterprise Act 2002

UK merger control is governed by the Enterprise Act 2002, as amended by the Digital Markets, Competition and Consumers Act 2024. The regime asks whether a “relevant merger situation” arises and, if so, whether it may result in a substantial lessening of competition (SLC) in a UK market. A joint venture engages this regime where it constitutes the acquisition of control of an enterprise, which is why the characterisation of the JV (full-function or not) matters so much to the notifiability question.

The UK regime is voluntary: there is no obligation to pre-notify. But that does not make notification optional in a commercial sense. The CMA can call in a qualifying merger, including a completed one, and can impose interim measures that freeze integration. The practical question, therefore, is not simply “must we file?” but “what is the risk of proceeding without filing?”

CMA jurisdiction and the share-of-supply test

The CMA assesses transactions using its Merger Assessment Guidelines, which set out how market definition and the SLC test are applied. Jurisdiction over a joint venture notification UK matter typically arises on one of two bases: a turnover threshold linked to the target enterprise, or a share-of-supply threshold where the parties together supply or acquire at least 25% of goods or services of a particular description in the UK (or a substantial part of it), with the transaction increasing that share.

The share-of-supply test is deliberately flexible. The CMA can define the relevant “description of goods or services” in a way that captures narrow overlaps. That flexibility is a double-edged sword: it gives the CMA jurisdiction in cases deal teams might assume fall outside the net, so internal screening should stress-test the narrowest plausible market definition, not only the broadest.

Turnover, share thresholds and voluntary notification

Where the turnover or share-of-supply thresholds are met, the CMA has jurisdiction and a voluntary notification becomes a realistic protective step. The Digital Markets, Competition and Consumers Act 2024 revised the jurisdictional thresholds, including the target turnover figure and the addition of an alternative “hybrid” threshold; verify the current figures against the CMA’s guidance before relying on them. Where the thresholds are not met, no filing is required, but the analysis showing that they are not met is precisely the evidence you must retain. Practically, run two internal screens at the earliest opportunity:

• Turnover screen. Aggregate UK-attributable turnover of the enterprises being combined, tested against the current statutory threshold.
• Share-of-supply screen. Estimate combined supply or purchasing shares on a “most likely” market and on the narrowest defensible market, flagging any figure that approaches the 25% threshold.

If either screen produces a figure close to a threshold, treat the JV as potentially notifiable and escalate. The margin for error in market definition is wide enough that “close” should mean “get advice”.

Full-function versus partial (non-full-function) joint ventures

What is a full-function joint venture?

A full-function JV is one that performs, on a lasting basis, all the functions of an autonomous economic entity. In practice, that means it has its own management dedicated to day-to-day operations, its own resources, assets, staff, finance, and it operates in a market in the same way as any other independent player, rather than merely performing an ancillary function for its parents.

The tell-tale features to assess are: operational autonomy; dedicated decision-making structures; sufficient assets and employees to trade independently; a lasting (not short-term project) character; and a market-facing role rather than dependence on the parents as its only customers or suppliers.

Consequences if the JV is full-function

A full-function JV may be treated as giving rise to a relevant merger situation. If the jurisdictional thresholds are met, it is capable of review by the CMA and the joint venture notification UK question is live. The prudent course for a full-function JV in an overlapping market is early engagement, either a voluntary filing or a pre-notification discussion, because the alternative is proceeding under the shadow of a possible call-in.

Partial and non-full-function JVs, where the line falls

Non-full-function JVs are more nuanced. Consider three patterns:

• Contractual cooperation. A distribution or joint-purchasing agreement with no separate entity and no change of control, generally not a merger situation, though it may still raise questions under the Competition Act 1998 if it coordinates competitive behaviour.
• JV with own legal personality but limited autonomy. A vehicle that exists on paper but depends on its parents for supply, customers and decisions, often non-full-function, but the analysis turns on the detail of governance and dependence.
• Partial-ownership JV with material influence. A minority stake can still confer control (including “material influence”) through veto rights over strategic decisions. Where it does, a change of control may arise even without a majority holding, this is the classic borderline case where you should seek CMA advice or counsel.

2026 reforms, what changed and the practical impact on notifiable joint ventures UK

Summary of the reform elements affecting JVs

The merger-control provisions of the Digital Markets, Competition and Consumers Act 2024, which took effect from 1 January 2025, have refined how the regime approaches jurisdiction and, in particular, the treatment of transactions that sit at the edges of the “merger situation” concept. For joint ventures, the practical significance is concentrated in three areas: revised jurisdictional thresholds (including the target turnover figure and a new “hybrid” threshold), a small-merger safe harbour, and continued attention to partial and non-full-function structures. The full reform picture is set out in our UK competition law reform 2026 (context) guide.

Where any reform element remains subject to guidance or transitional arrangements, treat it as subject to change and verify against the latest CMA and Government publications on the Competition and Markets Authority hub before relying on it for a filing decision.

Practical implications for deal teams

The net effect for a joint venture notification UK assessment is continued uncertainty at the partial-JV end of the spectrum. Structures that deal teams previously waved through as obviously non-notifiable still deserve a documented look. The practical effect, in the view of experienced practitioners, is that early CMA engagement and contemporaneous internal memos remain expected practice for any JV with a real market overlap.

Two behavioural changes follow. First, build the notifiability assessment into the deal timetable rather than treating it as a closing-eve check. Second, where the characterisation is genuinely finely balanced, budget for a short piece of merger counsel input, it is far cheaper than a retrospective inquiry that unwinds integration you have already begun.

Side-by-side comparison, notify the CMA versus do not notify

This table is the decision centrepiece. Use it to structure the internal debate, then retain the evidence noted in each row.

Read the table as a risk-allocation tool. The right-hand column is not “do nothing”, it is “do the analysis, then keep it”. The gap between the two columns is narrowest for partial JVs with veto rights, which is exactly where the recent reforms have raised the stakes. Where a row pushes you toward the left-hand column on any material dimension, escalate.

Practical steps, an operational checklist for a joint venture notification UK assessment

Pre-deal screening, a three-point quick screen

1. Legal form. Will the JV have its own legal personality, or is it a contractual arrangement? Does it acquire an existing business or its assets?
2. Governance. Who controls strategic decisions? Are there veto or reserved-matter rights that confer control or material influence?
3. Market thresholds. Run the turnover and share-of-supply screens on both the most-likely and narrowest markets.

Evidence and documents to assemble

• Turnover schedules. UK-attributable turnover for each enterprise being combined.
• Governance documents. Shareholders’ agreement, articles, board composition and reserved-matters list.
• The JV agreement. Scope, duration, dependence on parents for supply and customers.
• Financials and assets. Capitalisation, staff, and assets transferred to the vehicle.
• Market data. Internal or third-party estimates of combined shares.

Internal memo template, justifying a “no filing” decision

Copyable sample text: “On [date], the deal team assessed whether [JV name] gives rise to a relevant merger situation under the Enterprise Act 2002. The JV is [full-function / non-full-function] because [autonomy / assets / dependence on parents / duration]. Applying the CMA Merger Assessment Guidelines, combined UK turnover is estimated at [figure] and the combined share of supply of [description] is estimated at [figure] on the narrowest defensible market. On this analysis the jurisdictional thresholds are [met / not met]. The team has decided [not] to notify the CMA. This memo and its supporting screens are retained as the contemporaneous record supporting that decision, reviewed by [name/role] on [date].”

When to instruct merger counsel and what to brief

Instruct merger counsel where the JV is full-function in an overlapping market, where any share estimate approaches the 25% threshold, or where veto rights make control or material influence finely balanced. Brief them with: the JV agreement and governance documents; the turnover and share screens; a one-page transaction summary; and your target timetable. Ask for a clear deliverable, a notifiability opinion and, if needed, a filing or pre-notification strategy. For a shortlist of specialists, use the GLE lawyer directory, UK competition lawyers.

Download: the “Merger notification checklist UK, JV edition” packages this screening into a single working document your team can complete on each deal.

Examples and short case studies

Example A, full-function JV in manufacturing (notifiable)

Two manufacturers combine assets, staff and a dedicated management team into a new company that trades independently in an overlapping product market. The vehicle is full-function and combined shares are material. Here the joint venture notification UK analysis points to early engagement: a voluntary filing or pre-notification discussion avoids the risk of a completed-merger call-in and interim measures freezing integration.

Example B, non-full-function marketing JV (not notifiable)

Two firms create a contractual co-marketing arrangement with no separate entity, no transfer of assets and no change of control. Neither party acquires an enterprise. The documented conclusion is non-notifiable, but the team keeps the memo and governance analysis on file in case the arrangement is later scrutinised for coordination under the Competition Act 1998.

Example C, partial-ownership JV with material influence (borderline)

An investor takes a minority stake but negotiates veto rights over budget, strategy and senior appointments. Those rights may confer control (including material influence) despite the minority holding. This is the classic borderline case: seek CMA advice or counsel before completing, and do not assume the minority percentage settles the question.

Risks, remedies and enforcement, what to expect if the CMA investigates

The CMA process

Where the CMA reviews a JV, the assessment runs in phases. A Phase 1 review considers whether there is a realistic prospect of an SLC; if concerns cannot be resolved (for example, through undertakings in lieu of a reference), the matter proceeds to an in-depth Phase 2 investigation. The Competition and Markets Authority publishes the procedural framework and contact points for parties who wish to engage before completion.

Remedies, behavioural versus structural

If concerns are found, remedies fall into two families. Structural remedies, such as divestment of a business or asset, change the market structure. Behavioural remedies, such as access, supply or ring-fencing commitments, regulate conduct. The CMA can accept undertakings in lieu of a reference or prohibition. Practically, structural remedies tend to be preferred where a clean fix is available; behavioural remedies invite ongoing monitoring and are harder to negotiate. Early engagement gives parties more room to shape the remedy.

Penalties and gun-jumping

Proceeding without regard to the merger regime carries real exposure. The CMA can impose interim measures (an initial enforcement order) and can take enforcement action, including financial penalties for breach of those measures. For a JV that turns out to raise concerns, the downside of skipping the analysis is not merely delay, it can be forced unwinding of steps already taken. That asymmetry is the strongest argument for documenting the decision even when you conclude no filing is required.

Templates and annexes

Internal memo, sample paragraph: “The deal team concludes that [JV name] is non-full-function and does not give rise to a relevant merger situation because [reasons], and the jurisdictional thresholds are not met on any defensible market definition. Accordingly, no notification to the CMA is proposed. This conclusion is recorded contemporaneously and supported by the attached screens.”

• Checklist download. “Merger notification checklist UK, JV edition” (deal-team working document).
• Merger counsel brief template. Transaction summary, governance pack, turnover and share screens, target timetable, requested deliverable.

Supporting drafting resources, such as guides on structuring a JV to manage CMA notification risk and on partial acquisitions versus full-function JVs, extend these templates for transactional teams.

Conclusion and recommended next steps

The joint venture notification UK decision comes down to disciplined screening and a documented conclusion. Run the legal-form, governance and threshold screens early. If the JV is full-function and thresholds are met, engage the CMA. If it is clearly non-full-function with no change of control, proceed, and keep the memo that proves you looked. In the borderline partial-JV cases that the recent reforms have made riskier, instruct merger counsel before completion rather than after. To move fast on your next deal, complete the JV screening checklist and, where the answer is not obviously clear, brief a specialist through the GLE lawyer directory, UK competition lawyers.

Sources

1. Enterprise Act 2002
2. Competition Act 1998
3. Digital Markets, Competition and Consumers Act 2024
4. Merger Assessment Guidelines (CMA / GOV.UK)
5. Competition and Markets Authority
6. The Law Society, Competition Conference 2026