The law covers operating systems, office productivity software, email infrastructure, and document management systems. It exempts specialised technical systems — air traffic control, tax processing, defence — where no open-source equivalent exists and where migration risk is assessed as operationally unacceptable. Approximately 60 percent of current government IT expenditure falls within scope.
The practical challenges are significant. Dutch government IT staff have spent careers on Microsoft environments; retraining costs are estimated at €180 million. Legacy documents in proprietary formats number in the billions. Vendor contracts with exit clauses will cost an estimated €240 million to terminate early.
Proponents argue that the long-term economics are compelling: annual Microsoft licensing costs alone run to €340 million, which will be largely eliminated within three years of migration. They also cite the security argument — government software whose source code is publicly auditable is less vulnerable to undisclosed backdoors.
"We are paying every year to rent software we do not control, running on servers we do not own," said State Secretary for Digitalisation Alexandra van Huffelen. "That is not a technology strategy. That is a dependency."