Netherlands Shifts from Microsoft to Open Source Solutions

The Dutch Tax and Customs Administration has decided to halt its planned migration to Microsoft 365, pivoting instead towards open-source software options. This crucial decision comes in response to an ongoing commitment to enhance digital sovereignty within Europe.

Contextualizing the Shift

This move aligns with insights revealed at the recent Open Source Summit Europe, hosted by the Linux Foundation. In their 2026 State of Open Source in Europe report, the LF highlighted that a remarkable 94% of organizations within the European Union (EU) prioritize digital sovereignty, further underscoring its importance for 61% of those surveyed.

Leaving Microsoft Behind

Initially, the Dutch government planned a comprehensive transition to Microsoft 365, slated for completion by the end of 2026. At that point, roughly 5,000 employees had already transitioned. However, following a recommendation from the Dutch Advisory Council on ICT Assessment in June, concerns regarding the rollout prompted a reconsideration. The government promptly paused the initiative in July, shifting focus towards an on-premises and open-source strategy instead.

Concerns Prompting the Change

One primary concern identified in the ICT assessment was the inadequacy of the Microsoft 365 public-cloud design regarding information security and data processing capabilities. Additionally, the risks associated with utilizing American servers for sensitive documents raised alarms about data control and confidentiality.

The proposed encryption methodology within Microsoft 365 was another point of contention. The setup recommended using standard Microsoft encryption, as opposed to the preferred Double Key Encryption, which would have provided the government with enhanced control over its data security. The lack of default end-to-end encryption for one-to-one Teams calls, along with group call limitations, was also problematic for the Dutch authorities.

A Look Ahead

For the immediate future, the Dutch Tax and Customs Administration will continue using existing Microsoft software for email services, including Outlook. However, they are moving towards open-source solutions for personal storage and collaboration tools. Looking into 2027, State Secretary for Finance Eelco Eerenberg outlined plans to realize an on-premises mail and calendar solution followed by the implementation of open-source alternatives for collaboration and storage needs in 2028.

Distinctly, no specific open-source applications have been finalized yet. There’s been discussion around developing the Digital Autonomous Work Environment for Government (DAWO), which aims to swap out the Windows desktop for the NixOS Linux distribution.

Exploring Open-Source Alternatives

As they explore options, the government is considering various European open-source suites, including France's La Suite and Germany's openDesk. In addition, the team is looking at assembling a customized solution called MijnBureau, a self-hosted environment combining open-source tools like Nextcloud for storage, Collabora for document creation, Element for messaging, and OpenProject for management tasks.

While the full scope of the transition remains uncertain, the abandonment of Microsoft 365 signifies a significant step toward a more controlled and secure digital environment for the Dutch Tax and Customs Administration.