KEY TAKEAWAYS
- The UK’s Competition Appeal Tribunal certified the collective action against Microsoft, finding the claim “comfortably passes” the reasonable prospect of success threshold.
- Nearly 60,000 UK businesses and organizations are represented in the case, which alleges Microsoft charges higher wholesale prices for Windows Server on AWS and Google Cloud than on its own Azure platform.
- Total liability could reach up to £2.1 billion if Microsoft is found to have abused its market position.
- Microsoft confirmed it plans to appeal the tribunal’s certification decision, while also disputing the underlying allegations.
London’s Competition Appeal Tribunal ruled on 22 April 2026 that Microsoft must face a collective action lawsuit representing nearly 60,000 UK businesses. It dismissed Microsoft’s objections and granted a Collective Proceedings Order, allowing the case to proceed to trial.
As reports note, the tribunal found the claim has a reasonable prospect of success. This is an early procedural win for lead claimant Dr. Maria Luisa Stasi.
Filed in December 2024, the case alleges Microsoft’s Windows Server licensing creates an uneven cloud market. Businesses are charged more when they run Windows Server on rival platforms such as Amazon Web Services and Google Cloud than on Microsoft’s own Azure.
What the Case Alleges Against Microsoft’s Pricing Structure
The core allegation, reported by Tom’s Hardware, is that Microsoft uses a two-tier pricing model for Windows Server that disadvantages cloud rivals to Azure.
Businesses running Windows Server on Amazon Web Services, Google Cloud, or Alibaba Cloud pay higher wholesale licensing rates than on Azure. These costs are passed to customers, making Azure cheaper for the same software due to licensing, not efficiency.
The claim argues this exploits Microsoft’s dominant position in enterprise operating systems to steer customers towards Azure, harming competition. This tension persists even as the UK launches its £500M Sovereign AI Unit to bolster domestic tech independence.
The proposed class includes about 59,000 UK businesses, each estimated to have lost tens of thousands of pounds. At the upper end of the damage estimate, the claim is valued at £2.1 billion.
The Tribunal’s Decision and Microsoft’s Response
At this stage, the Competition Appeal Tribunal did not assess whether Microsoft is guilty.
It only decided whether the case can proceed as a collective action. As reported by The Register, the tribunal found the claim meets that threshold and granted a Collective Proceedings Order on an opt-out basis.
A final order, including opt-out deadlines and hearing dates, is expected within weeks.
Dr. Maria Luisa Stasi said Microsoft’s practices caused real financial impact, and she is preparing for a trial to recover losses. Civo CEO Mark Boost said a level playing field is essential for innovation and choice, reflecting wider UK tech trends favouring competition.
Microsoft responded that it will appeal, arguing the tribunal failed to follow recent Supreme Court of the United Kingdom precedent on class action certification. It also disputes the claims, noting the decision makes no final ruling on the allegations.
The company previously argued the claim lacks a workable method to calculate losses and that its integrated model, using Windows Server for Azure while licensing it to rivals, can support competition.
The Broader Regulatory Picture
This ruling is part of wider scrutiny of Microsoft’s cloud licensing. Tom’s Hardware reports that regulators across multiple regions are examining its practices.
In July, the Competition and Markets Authority found Microsoft’s licensing disadvantaged Amazon Web Services and Google Cloud in the UK market. The Federal Trade Commission is also investigating, alongside authorities in Japan.
In Europe, Microsoft settled with CISPE in 2024, agreeing to change its practices and pay compensation to avoid an EU antitrust probe. Google has also filed a complaint with the European Commission on the same issue.
According to Windows Central, the UK case is Microsoft’s largest legal challenge in cloud licensing so far. With a trial confirmed, it is likely to become the key competition test of its cloud business.
Source: Microsoft must face $2.8 billion UK lawsuit over cloud
