AWS estimates half of the workloads Microsoft enterprise customers run on Azure would migrate away from the Windows giant’s cloud if only the licensing costs of doing so were not prohibitively high and a competitive deterrent.

This claim is made in the latest submission by AWS to the UK’s Competition and Markets Authority’s (CMA) Cloud Services Market Investigation.

Changes introduced by Microsoft in 2019 made it up to four times more expensive to run Windows Server outside the Azure public cloud – for example, on AWS, Google, or Alibaba’s infrastructure. AWS has complained of this before, and Google filed a complaint with the European Union’s antitrust team in September to press for an inquiry.

AWS said that Microsoft’s licensing practices are harming competitors and competition for cloud workloads in the UK. It said that Microsoft does not have a credible justification for why it has made changes. AWS said that Microsoft is harming consumers, competitors, and competition by artificially raising prices, preventing price reductions and diverting customers to its own services