Once you have received your VVR, BSN number and by law, you have to get a basic medical insurance (basis ziektekosteverzekering). A comparison website you can look at: www.independer.nl. The insurance you choose has to cover you for admittance to a sanatorium or psychiatric institution. Most have it included but just double check. Please be aware that your medical aid will be back dated to the day you arrived in the Netherlands and that includes the costs as well. Recently we learned that for knowledge migrants they are only supposed to back date it to the date when your contract starts but the insurance companies are not always aware of this rule.