You stay in the Netherlands for 4 months or longer
If you stay in the Netherlands for 4 months or longer, you must register as a resident with the municipality where you live. You must do so within 5 days after your arrival in the Netherlands. If your partner and/or children also stay in the Netherlands for 4 months or longer, they must also register with the municipality.
Apart from this registration with the municipality, you must also apply for any relevant permits, for example a residence permit or work permit.
More information about the registration
More information about registration as a resident and non-resident with a Dutch municipality can be found at rijksoverheid.nl (only available in Dutch).