Background: Several healthcare systems have elements of managed competition in which citizens can choose between multiple insurers. In order for this principle to function properly, all citizens should have equal opportunities to switch insurer. Studies, conducted around 2015, have shown that the supplementary insurance policy is perceived by citizens as a barrier to switching, which could have negative consequences for the intended goals of the system. We aim to explore whether a supplementary insurance policy still has a restraining role on the opportunity to switch among citizens in the Netherlands from 2015 to 2020. Furthermore, we will examine if the extensiveness of the supplementary insurance policy relates to the switching behaviour of citizens. This element has not been addressed in previous studies. Methods: We obtained information on the role of the supplementary health insurance policy in the switching behaviour of citizens by sending questionnaires, yearly in February from 2015–2020, to 1,500 members of the Dutch Health Care Consumer Panel (DHCCP) each year. As such, we were able to examine whether having a supplementary insurance policy plays a role in the decision of Dutch citizens to switch insurer. The response rates were consecutively from 2015 to 2020: 60% (n = 896), 47% (n = 703), 44% (n = 659), 50% (n = 751), 48% (n = 715), and 54% (n = 806). Results: Citizens with a supplementary insurance policy switch less often than citizens without one. The extensiveness of the supplementary insurance policy is significantly associated with the decision of citizens to switch insurer; the more extensive citizens are insured, the less often they switch. Additionally, our results show that every year a small group of citizens does not switch insurer because they are concerned that they will not be accepted for a supplementary insurance policy. Conclusions: Our results indicate that having a supplementary insurance policy holds citizens back from using their opportunity to switch. This contributes to the ...