The UK Competition and Markets Authority has invited comments on Microsoft's business software ecosystem, prompting formal submissions from industry stakeholders including the Browser Choice Alliance.
The regulator is examining Microsoft's position across business software, with browsers emerging as a central issue. Published submissions argue that browsers are a key route to internet services and web-based workplace tools, making their treatment within Windows and related Microsoft products significant for competition.
One of the first published responses came from the Browser Choice Alliance, a coalition of browser providers seeking regulatory action on browser choice. Its submission argues that Microsoft uses its position in operating systems and productivity software to steer users toward its own browser.
"The BCA believes that this investigation is an important first step towards ensuring free and fair competition within Microsoft's business software ecosystem, including between browsers, which are the key gateway for PC users to access the internet and web-based services," said the Browser Choice Alliance.
The group also alleges that Microsoft's conduct affects competition beyond browser downloads. It argues that distribution arrangements and design choices within Microsoft's software environment can shape which services users adopt for work, including newer AI tools.
"Microsoft leverages [its] market power to hinder merit-based competition, user choice and innovation in the UK. Instead of competing on features and innovation, Microsoft relies on portfolio-wide distribution channel exclusivity and various anti-competitive steering practices to force the use of its own browser and thus undermine effective choice," said the Alliance.
Browser focus
The submission emphasises the role of Windows PCs in office work and the overlap between personal and business use. That matters because the CMA's inquiry focuses on business software, while many browser habits and software choices are formed across devices used for both work and personal tasks.
According to the Alliance, the distinction between consumer and professional use is often blurred. Employees may use one Windows device for both workplace productivity and personal browsing, making default settings and prompts more influential over time.
"The practical reality is that consumer and business use cases frequently overlap, making it difficult to draw a sharp distinction between them. There is often no clear-cut boundary between personal/work devices and personal/work use. A given Windows device may be used for both personal and professional activities," said the Alliance.
Windows shift
The filing also points to the migration from Windows 10 to Windows 11 as a relevant market development. The Alliance argues that as organisations move to newer versions of Windows, Microsoft has another opportunity to shape defaults and influence browser adoption in workplaces.
It adds that the regulator is right to pay close attention to Windows 11 because of its role as Microsoft's main operating system in the UK business market. Changes in operating system versions can affect how browser choice screens, prompts and settings are presented to users.
"The CMA is right to focus on Windows 11 as Microsoft's "main operating system in the UK". In October 2025, Microsoft ended support for Windows 10. Organisations and their users are therefore migrating to Windows 11 - a one-way and irreversible upgrade that is incentivised by the deprecation of support for Windows 10," said the Alliance.
AI implications
The submission links browser competition to the wider contest over AI assistants, productivity services and research tools. It reflects a broader industry view that browsers are no longer just access points for websites, but gateways to workplace software and AI products delivered through the web.
The Alliance argues that the importance of PCs is growing as companies adopt generative AI for document work, coding and research. In that context, control over browser distribution could influence which AI products users encounter first and which tools become embedded in daily workflows.
"The importance of Windows PCs is only increasing in the age of generative AI. Key generative AI use cases include productivity, deep research and coding. These tasks are all especially well-suited to being carried out on PCs," said the Alliance.
The filing also warns that competitive concerns in browsers could extend into AI if Microsoft applies similar methods to promote its own services. It argues that companies should be able to choose AI tools independently, rather than through prompts or defaults tied to Microsoft's wider software estate.
"... organisations and their users should be free to choose the AI tools that they want, not have to make do with the solution imposed by Microsoft. But, absent intervention, the BCA is concerned that Microsoft will deploy its tried-and-tested browser dark pattern tactics to similarly distort competition and user choice in the AI space," said the Alliance.
The Alliance concludes that browser competition has direct consequences for business users, developers and software markets linked to the browser. "Microsoft's tactics leverage its dominant Windows OS and M365 productivity software suite to frustrate users' choice of browsers, thereby damaging the user experience and lowering productivity for millions of businesses in the UK. This undermines the efforts of many differentiated, innovative browser developers to compete and reach new audiences..." said the Alliance.