Child is a dependent on parents health insurance and a spouse on her husband health insurance who would be primary?

The governing body National Association of Insurance Commissioners (NAIC) has not yet determine the coordination of benefits rule for dependent adult children who are also on their spouse's plan.

However, most group insurance policies have "coordination of benefits" rules to determine which plan is primary under various circumstances. Each health plan's rules would have to be reviewed in each specific case, but common coordination of benefits rules are:

1. If one of the plans doesn't have coordination rules, that plan will be the primary plan.
2. A plan that covers you as an employee, rather than as a dependent, will be your primary plan.
3. If you are covered as a dependent by more than one plan, the plan of the employee/policyholder whose birthday is first in the calendar year will be primary for you. For example, you're covered by your parent's health plan and your spouse's health plan. Your parent's birthday is June 3 and your spouse's birthday is November 11. Since your parent's birthday is earlier in the year than your spouse's birthday, your parent's plan will be primary for you.
4. If a determination can't be made, the plan that has covered you longer will be primary.

It's also possible that the parent's plan will no longer cover the child once she is married - but some plans do have very liberal eligibility rules, and a married child might be able to continue coverage under her parent's plan.

Keep in mind that the above are just general examples of coordination rules, and the rules that are specified in your plans may be different.