When both parents have the same birthday, which insurance should be primarily used to cover their child?

The correct choice is based on the guidelines established for determining the primary insurance for dependents when both parents have the same birthday. In situations where both parents have identical birthday details, the policy that has been active the longest is typically considered primary. This guideline is part of the "birthday rule," which usually applies to children who are covered under both parents' health insurance plans.

Using the longest active policy ensures that the child benefits from the stability of coverage and the most established insurance plan, which might offer better overall benefits and continuity of care. It creates a standardized approach to avoid confusion and disputes over which parent's insurance should be billed first.

The other options, such as using the insurance based on income, procedure coverage, or deductible structure, do not align with the standard practices set forth by insurance guidelines regarding dependent coverage. They introduce unnecessary complications and do not reflect the methods typically recognized in determining primary payer responsibility.