Here we go again: Microsoft in UK court over cloud licensing
Summary
The Competition Appeal Tribunal (CAT) is hearing a bid to allow a collective action brought by Dr Maria Luisa Stasi alleging Microsoft overcharged UK organisations for running Windows Server on rival cloud platforms (Google, AWS, Alibaba) to push customers toward Azure. The proposed class covers roughly 59,000 members, with average losses reportedly in the tens of thousands of pounds and potential compensation exceeding £2 billion if abuse of market power is proven.
The case was filed in December 2024; this hearing is to decide whether the CAT will grant a Collective Proceedings Order so the matter can proceed to trial next year. Stasi’s team estimates trial costs of £18.4 million and has litigation funding from Litigation Capital Management to cover adverse costs. Microsoft calls the action opportunistic and tied to complaints by Google; regulators including the UK CMA have already flagged higher charges for Microsoft software on rival clouds earlier this year.
Key Points
- The CAT must decide whether to allow a class action over alleged cloud licensing overcharging by Microsoft.
- The Proposed Class is about 59,000 members across many sectors, with individual losses described as tens of thousands of pounds.
- Potential liability for Microsoft could exceed £2 billion if the claim succeeds at trial.
- Stasi estimates trial costs of £18.4 million and has litigation funding via Litigation Capital Management to underwrite risks.
- Microsoft disputes the claims as opportunistic; Google has previously complained about Microsoft’s licensing practices.
- The UK Competition and Markets Authority found evidence in July 2025 that Microsoft charged higher prices for software used on rival clouds; the company has made some concessions in response to regulatory scrutiny.
Context and relevance
This is a high-stakes competition-and-licensing fight that matters to cloud customers, resellers and smaller cloud providers. If the CAT allows the case to proceed and the claim later succeeds, it could reshape commercial terms for running Microsoft workloads off Azure, strengthen calls for interoperability and fair access, and encourage further regulatory or litigation action across Europe and the UK.
For cloud vendors and enterprises, the case sits at the intersection of pricing strategy, market power and platform lock-in — themes that have dominated regulatory scrutiny of big tech in recent years.
Why should I read this?
Short version: if you run Windows Server in the cloud, sell cloud services, or negotiate enterprise licences, this could hit your costs or change how vendors price cross-cloud usage. It’s about competition, a possible £2bn pay-out and whether the cloud market will stay open — so yeah, worth five minutes of your time.