Coordination of Benefits, commonly called COB, is the process insurance companies use when someone is covered under more than one medical or dental plan. While dual coverage can reduce your out-of-pocket costs, it does not mean you can collect twice for the same service.
Understanding how Coordination of Benefits works can help you avoid claim delays, unexpected bills, and confusion about which plan pays first.
What is Coordination of Benefits?
COB applies when you are enrolled in two plans at the same time. This commonly happens when:
- You are covered under your own employer’s plan and under your spouse’s plan
- A child is covered under both parents’ plans
- You have active employee coverage and are also enrolled in Medicare coverage
When dual coverage exists, one plan is designated as the primary plan and pays first. The other plan becomes the secondary plan and may pay some or all of the remaining eligible balance, depending on its provisions.
Here is the key rule. You cannot double dip. The total payment between both plans cannot exceed 100 percent of the allowable expense. Insurance is meant to cover costs, not create a financial gain. If the primary plan pays the full allowable amount, the secondary plan may pay little or nothing.
How is the Primary Plan Determined?
For employees, your own employer-sponsored plan is typically primary over a plan where you are covered as a dependent.
For dependent children, insurers generally follow the birthday rule. The parent whose birthday falls earlier in the calendar year has the primary plan for the child.
If parents are divorced or separated, court orders and custody arrangements may determine which plan is primary.
It is also important to note that medical and dental plans coordinate benefits separately. The primary order under your medical plan may not mirror your dental plan.
Why Does COB Matter?
If your insurance carriers do not have accurate information about other coverage, claims can be delayed, denied, or processed incorrectly. Many carriers periodically request verification of other insurance to keep records current.
If a claim is processed in the wrong order, it may need to be reprocessed once the correct primary and secondary plans are established.
Keeping both insurers informed, especially after marriage, divorce, or a job change, helps ensure your medical and dental claims are paid accurately and efficiently.