Insurance companies require 80% participation in their group health insurance plans. They do this to avoid “adverse selection.” This just means that by demanding 80% participation they know that they will get lots of healthy people in the plan. If they did not require a participation rate then they might just get employees with medical problems to enroll.
Now the 80% participation rate becomes a problem with international organizations. For example if an organization has 20 employees, 10 being in Africa and 10 in Western Europe, the 10 in Western Europe may be perfectly happy with European government sponsored health insurance. Thus the organization can not get them into a group plan and because of that can not get the required 80% participation.
The way around that situation is to “carve out” the African group and request a group health insurance plan with parameters as follows “Group Health Insurance for Employees in Africa Only.” Of course this means that any new employees joining the organization and heading for Western Europe will not be able to join the group health plan. But it also means that those employees in Africa can now have their own group health insurance plan.