Most group health insurance plans have adopted the coordination-of-benefits rules developed by the National Association of Insurance Commissioners. Under these rules, if a dependent child is covered by both of the health insurance plans of the child's married parents, which health plan is primary for the child's medical expenses?

The health plan of the parent that first celebrate his/her birthday in the calendar year will be the primary for the child's medical care.

Explanation:

The National Association of Insurance Commissioners is a board that was set up to play role in protecting the interest of insurance customers.

They implemented a regulation which is known as the coordination-of-benefits rules, and has been adopted by most of the health insurance group.

The coordination - of -benefits rule is implemented for the elimination of benefits duplication or over-insurance. It is useful when a person is covered by two or more plan that include health benefits.

In this case of the child, the coordination-of-benefits rule must be implemented because he/she is covered by two health plan.