You are only under a duty to notify if you are a foreign company established abroad. If your company is established in the Netherlands and your employees are employed according to Dutch job contracts, notification is not necessary.
The duty to notify does not apply if your employees work in the transport sector and your business is in one of the subsectors (see https://www.postedworkers.nl/werkgever/transportsector) or if your employees work in the public administration, government services or extraterritorial organisations sectors.
Furthermore, the duty to notify does not apply if incidental work is performed in the Netherlands, for example business meetings, attending congresses, or urgent repairs etc. Please note: this list is not exhaustive, and some additional requirements apply. For example, urgent maintenance / repairs / installation are not subject to the duty to notify if you, as a foreign contractor, have also supplied the asset in question yourself.
There is no duty to notify either for ongoing (temporary) assignments that started before 1 March 2020.