What determines which parent's insurance coverage is primary for a child covered by both?

In situations where a child is covered by both parents' insurance plans, the primary insurance provider is determined through a method known as the "birthday rule." This rule states that the parent whose birthday falls earlier in the calendar year typically holds the primary coverage for the child.

This approach helps simplify coordination of benefits between the two plans, ensuring that one plan pays first and that there is no confusion over which insurance is responsible for covering medical expenses. The rationale behind using the birthday rule rather than other factors like age, amount of coverage, or parental income lies in its straightforwardness and ease of application. It avoids complex calculations or negotiations about financial capabilities or contributions to insurance premiums.

While factors such as age, coverage amounts, or income may influence personal circumstances or insurance choices for families, they do not dictate the primary insurance coverage for dependent children in this context. Hence, the birthday rule is widely accepted and utilized in practice for determining insurance responsibilities when both parents have coverage.