If you travel abroad temporarily (for instance, for purposes of studies, leisure, temporary job, visiting relatives, etc.) and the center of your life is in Israel:
Before you leave the country, you must fill-out a multi-annual report form and provide it to the Insurance and Collection Department of the branch nearest to your place of residence or by means of the internet site.
If the goal of your travel abroad is to reside and establish your center of life outside of the country:
You have to fill-out a questionnaire for determining residency of persons living abroad, and provide it to the Insurance and Collection Department of the branch nearest to your place of residence or by means of the internet site.