When a faulty product, a misleading sales practice or an anti-competitive arrangement causes a small loss to a very large number of people, the arithmetic rarely works for an individual lawsuit. A loss of a few pounds cannot justify the cost, time and risk of taking a case to court. The UK’s answer to that problem is the consumer group claim: a single set of proceedings that stands in for a whole class of affected people.
The mechanics matter, because “group claim” covers more than one legal route and the rules differ sharply between them. This guide explains how consumer group claims work in the UK: who can bring one, how the Competition Appeal Tribunal (CAT) decides whether it may proceed, what opt-in and opt-out really mean, and what happens to any money that is recovered.
A group claim is not automatically a “class action”
The United States-style class action has no exact equivalent in the UK. Instead there are broadly two routes for bundling many similar consumer claims together, and the difference between them is not a technicality.
The first is a group litigation order (GLO), managed in the High Court under the Civil Procedure Rules. A GLO is used where a number of claims share common issues of fact or law, and it is generally an opt-in arrangement: people who want to be part of it have to register.
The second is a collective proceeding in the Competition Appeal Tribunal. This route was created for breaches of competition law, and it is the only one of the two that can operate on an opt-out basis. It is governed by section 47B of the Competition Act 1998, as inserted by the Consumer Rights Act 2015.
That split explains why so many high-profile UK “group claims” sit in a specialist tribunal rather than the ordinary courts. The remainder of this article focuses on the CAT route, because it is the one with the distinctive opt-out feature.
The gate the Tribunal keeps: certification
Nothing proceeds automatically. Collective proceedings may continue only if the Tribunal makes a collective proceedings order (CPO). The Tribunal is not a rubber stamp; it acts as a gatekeeper to prevent inappropriate claims from being brought in this form.
To obtain a CPO, a proposed class representative has to satisfy the Tribunal that it is “just and reasonable” for that person or body to act in the role, and that the claims raise the same, similar or related issues of fact or law and are suitable to be brought collectively. The representative does not have to be a member of the affected class, but the Tribunal must be persuaded that the arrangement is appropriate.
Claims come in two types. Follow-on claims rely on an earlier finding of infringement by a competition authority such as the Competition and Markets Authority. Standalone claims do not, and must prove the infringement from scratch. When the regime was designed, follow-on cases were expected to dominate. In practice the opposite happened: the government’s review of the regime notes that roughly 90 per cent of the current caseload is now made up of standalone claims.
Opt-in versus opt-out: the fork that decides everything
Once it certifies a case, the Tribunal must specify whether it proceeds on an opt-in or an opt-out basis. The definitions come directly from statute:
- Opt-in proceedings are brought only on behalf of class members who actively join by a specified date.
- Opt-out proceedings are brought on behalf of every class member in the defined class except those who opt out. A class member who is not domiciled in the UK at the relevant date must still opt in to be included.
| Feature | Opt-in | Opt-out |
|---|---|---|
| Who is included | Only those who actively join | Everyone in the defined class, except those who opt out |
| Action required by a class member | Must opt in by a set date | No action needed to be included |
| Non-UK domiciled members | Must opt in | Must also opt in |
| Who the outcome binds | Only those who opted in | All class members who did not opt out |
| Where it is typically used | High Court group litigation; some CAT cases | CAT competition claims, where the Tribunal directs |
| Main trade-off | Clearer participation; smaller class | Wider reach; larger burden on the defendant |
The definitions of opt-in and opt-out proceedings are set out in section 47B(10) and (11) of the Competition Act 1998, as inserted by the Consumer Rights Act 2015.
Which basis applies is a discretionary decision for the Tribunal, guided by the Competition Appeal Tribunal Rules 2015. The rules allow the Tribunal to weigh all matters it considers relevant and specifically single out two: the strength of the claims, and whether it is practicable for the proceedings to be brought as an opt-in case, including the estimated value of individual class members’ claims.
In December 2025 the Supreme Court addressed how that discretion should be exercised. It held that there is no general legislative presumption in favour of either opt-in or opt-out; the choice is for the Tribunal on the facts. The strength of the claim is not treated as a purely neutral factor either, and may carry weight depending on the circumstances, particularly in assessing whether certifying an opt-out claim can achieve a just outcome.
The argument on the other side
Opt-out proceedings are powerful precisely because they reach people who would never sign up to a lawsuit. That same reach is the source of the main objection, and it is worth stating fairly rather than dismissing.
Because a single case can bind a very large class, defendants may face substantial exposure and heavy defence costs. Critics of the model argue this can pressure companies to settle claims that might not succeed if tested individually. The Supreme Court itself has acknowledged this risk as part of the reason the Tribunal is given a gatekeeping role.
The counter-argument, made by consumer advocates and reflected in the regime’s design, is that without an opt-out mechanism, losses too small to litigate one by one would simply go uncompensated, and there would be little deterrent against conduct that harms many people in small amounts. The government’s framing of the issue is that the aim is to strike the right balance between access to redress and the burden placed on business, and it is reviewing whether the current rules achieve that. That review is set out in the government’s call for evidence on the opt-out collective actions regime.
Two structural safeguards sit between the two positions: certification, which decides whether a claim may proceed collectively at all, and the requirement that settlements be approved as just and reasonable.
What happens if a case settles
Most certified cases do not reach a full trial. Where the parties reach an agreement, the collective settlement regime applies and the parties ask the Tribunal to approve it. The Tribunal will only approve a settlement if it is satisfied the terms are just and reasonable. An approved settlement is generally binding on class members unless they opted out, and funds are then distributed to eligible members who come forward after they are notified.
How much an individual receives varies considerably from case to case. In the largest settlement to date, against Mastercard, the total was around £200 million, of which £100 million was set aside for class members. The government’s review notes that individual class members could expect approximately £45 each, and no more than £70. Those figures are specific to that settlement and that class, not a general rule.
A recurring practical problem is take-up. If not everyone eligible comes forward, residual funds arise. Under the regime, undistributed damages from opt-out cases go to a prescribed charity, the Access to Justice Foundation, which regrants them to free legal advice services. The Tribunal has also recognised the Foundation as an appropriate recipient of unclaimed funds in settled cases, and has approved a significant payment to it in at least one such matter. The rules on unclaimed settlement funds are one of the questions the government is consulting on.
What the record shows so far
The regime is now roughly a decade old, and the shape of the caseload has surprised those who designed it. According to the government’s review, claims have sought damages in the tens of billions of pounds, hundreds of millions have been spent on legal fees, and approximately 90 per cent of cases are standalone rather than follow-on.
Just as striking is how few cases have been decided on the merits. Only one opt-out claim has reached a full judgment in the Tribunal; it concerned residential landline pricing, and the claim was unsuccessful. Most certified cases have ended in settlement or have not yet concluded, which means there is still limited precedent on how damages are calculated and how funds are distributed at scale.
Because these cases can involve millions of people, they tend to attract sustained media attention as they move through the Tribunal. For further reporting, national business sections and specialist legal outlets often track the larger claims alongside the Tribunal’s own published judgments.
If you think you are part of a class
In an opt-out case, being included does not require you to do anything. But receiving a share of any money is different: in practice you usually have to make a claim when a settlement or award is confirmed and a notice is issued. If you do nothing, you may be included in the outcome but not receive a payment.
Notices about certified cases and settlements are published through official channels, and it is sensible to verify anything you receive against those sources rather than acting on an unexpected message alone. You are generally not required to pay an upfront fee to be included in an opt-out class, and a request for one should prompt questions.
If you are domiciled outside the UK, the opt-out default does not apply to you: you must opt in if you want to be included in a UK opt-out proceeding. And if you would rather pursue your own claim separately, the right to do so is preserved by the legislation, subject to the usual time limits.
Frequently asked questions
Can I bring a group claim for any kind of consumer problem?
No. The opt-out collective proceedings regime in the CAT applies only to losses caused by breaches of competition law. Other kinds of consumer harm, such as defective goods or poor services, may be pursued through a High Court group litigation order or through individual claims, but those routes are typically opt-in and follow different procedural rules.
What is the difference between opt-in and opt-out in one sentence?
In opt-in proceedings you have to join to be included; in opt-out proceedings you are included unless you ask to leave.
Do I have to pay to join a group claim?
Generally you do not pay an upfront fee to be included in an opt-out class. Cases are usually funded through third-party litigation funding or contingency arrangements, and the Tribunal reviews settlements and funding questions. The details vary by case, so the terms set out in the case-specific notice are what matter.
How much money will I get?
It depends heavily on the case. After legal and funding costs are accounted for and the class is distributed, individual payments are often modest. In the largest settlement to date, individuals could expect roughly £45 and no more than £70, according to the government’s review. Those figures are case-specific.
What happens to money that nobody claims?
For opt-out cases, undistributed damages go to a prescribed charity, the Access to Justice Foundation, which uses them to support free legal advice. For settled cases, the destination of unclaimed funds has been decided case by case and is the subject of an ongoing consultation.
How long does a group claim take?
Typically years, not months. Certification, evidence, trial or settlement, and the distribution of any money are all separate stages, and complex competition cases can take a long time to resolve.
Where the regime is heading
The most useful way to think about UK consumer group claims is that they are not one thing. They are a certification decision, a choice between opt-in and opt-out, a settlement or trial, and then a distribution process – and each stage has its own rules and its own way of determining who benefits.
That last stage is the one to watch. A regime can be judged by the damages it claims, but it is actually experienced by consumers through what lands in their hands, and the evidence so far suggests that the size of a headline figure and the size of an individual payout can diverge sharply. As the government reviews funding, certification, settlement and distribution together, the practical question – whether money reaches the people it was meant for – is likely to matter more than how large the claims have grown.
