Arriving with solid coverage from home makes a second, Dutch policy feel redundant, and plenty of new residents delay on exactly that reasoning. The verzekeringsplicht (insurance obligation) is triggered by working or registering here rather than by whether cover already exists elsewhere, and the window that follows is shorter than most people assume.
Yes, once you're actually working or otherwise registered as a resident here — foreign coverage, even good coverage, doesn't exempt you from the Dutch system if you're subject to it. The verzekeringsplicht (insurance obligation) kicks in from the date you start working under a Dutch employment contract, or in some cases from formal residence registration, regardless of what you're still paying for back home. You get four months from that trigger date to take out a Dutch basisverzekering (basic policy); register within that window and it's backdated to the start, so there's no coverage gap. Miss it and CAK — the body that cross-checks insurance records against municipal and tax data — will eventually catch it, and you'll owe backdated premiums plus penalties on top. The real exceptions are narrower than people assume: full-time students here only to study, not working, are exempt and shouldn't try to enrol at all; certain cross-border workers who live in the Netherlands but are insured through an employer in another EU/EEA country can stay on that scheme instead under EU coordination rules; and posted workers on a genuinely temporary assignment sometimes keep home coverage too. Outside those specific cases, assume you're obliged and register promptly rather than waiting to see if anyone notices.