How do I register with the CAK? Do you live in a treaty country? And are you receiving a statutory pension or statutory benefit from the Netherlands? If so, you need to apply for a document S1/form 121 from us. With the S1/121 you register with a healthcare fund in your country of residence. Only after registration you can use medical care in your country of residence. Tip Are you planning to emigrate to a treaty country? Find more information at I am moving abroad. On the website Netherlandsworldwide of the Ministry of Foreign Affairs you'll read what else you need to know besides health insurance.