The Dutch tax office abandons Microsoft 365 and brings email and calendars on-premises in 2027

On October 7, 2026, the Dutch State Secretary for Finance announced that the Tax and Customs Administration is dropping its Microsoft 365 migration: email and calendars move on-premises in 2027, with European open source for storage and collaboration to follow. For European IT leaders, it is the most concrete signal yet that sovereignty is no longer a slogan but a budgeted trajectory.