Does new medical insurance coverage automatically become the primary coverage?

Not necessarily. When a person has multiple health insurance policies, the order in which they are applied is determined by the coordination of benefits (COB) rules. These rules are set by the insurance companies and can vary. However, in general, the primary coverage is the one that is responsible for paying for the majority of the medical expenses, while the secondary coverage is responsible for paying for the remaining expenses.

The primary coverage is usually the one that:

- Is provided by the employer of the person who is the main policyholder

- Has been in effect the longest

- Covers the person who has the most medical expenses

- Is specifically designated as the primary coverage in the policy documents

If the COB rules do not clearly indicate which policy is the primary coverage, the insurance companies will work together to determine the appropriate order of payment.