The main rule
The Cbw applies to essential and important entities that are established in the Netherlands and provide their services in the Netherlands or another Member State [1]. The establishment in the Netherlands is decisive, not the nationality of the shareholder.
Digital providers: the main establishment
For, among others, providers of cloud computing services, data centre services and managed (security) services, the Cbw applies if their main establishment or representative is in the Netherlands [2]. The main establishment is where the decisions on cybersecurity measures are mainly taken [3].
Size counts per group
Whether you are medium-sized or larger, you determine with the European SME definition, in which linked and partner enterprises may count. See the question on essential and important entities.
In practice
A group with establishments in several countries deals with several supervisory authorities and reporting points. Register the Dutch entity in the Dutch register and state there in which Member States you provide services [4].