Which Parent’s Insurance Is Primary?

When a child has multiple health insurance policies, identifying the “primary” plan, which pays first, and the “secondary” plan, which covers eligible remaining costs, is important for managing medical expenses. This hierarchy helps families navigate claims and affects out-of-pocket expenses. Rules for determining primary coverage prevent duplicate payments and ensure combined benefits do not exceed total care costs.

Determining Primary Coverage for Married Parents

For married parents, the “birthday rule” is a widely adopted standard used by insurance companies to establish which parent’s plan is primary for a dependent child. This rule dictates that the health plan of the parent whose birthday falls earlier in the calendar year is considered the primary insurer. Only the month and day of birth are considered, not the year of birth or the parent’s age.

For example, if one parent’s birthday is March 15th and the other’s is October 20th, the parent with the March birthday would have the primary coverage. The plan of the parent with the October birthday would then serve as the secondary coverage.

Specific situations modify the birthday rule. If both parents share the same birthday, the plan that has covered the child longer typically becomes primary. If one parent has active employer coverage and the other has coverage through a former employer like COBRA, the active employee’s plan is generally primary.

Determining Primary Coverage for Divorced or Separated Parents

When parents are divorced or separated, the determination of primary health insurance for a child often involves considerations beyond the birthday rule. The most significant factor is typically a court order or divorce decree, which may explicitly state which parent is responsible for providing health insurance coverage. These legal documents supersede other general rules and must be followed.

Without a specific court order, the health plan of the custodial parent (the parent with whom the child lives most of the time) is usually primary. This rule provides a default mechanism when legal directives are absent. State laws consistently require both parents to provide for their children, including health insurance.

Remarriage and new family structures can influence primary coverage. If the custodial parent remarries and the child is added to a step-parent’s health plan, the custodial parent’s plan usually remains primary. The step-parent’s plan would typically be secondary, with the non-custodial biological parent’s plan potentially acting as a third payer.

Understanding Coordination of Benefits

After the primary insurance plan processes a claim and pays its share, coordination of benefits (COB) takes effect. COB is the system insurers use to determine how multiple health plans work together to pay for medical services. This prevents overpayment and ensures each insurer contributes appropriately.

The remaining balance of a medical bill, after the primary insurer has paid, is then submitted to the secondary insurance plan. The secondary plan reviews the claim and may cover additional costs that the primary plan did not, such as deductibles, copayments, or coinsurance, up to its own coverage limits. For example, if a medical procedure costs $1,000 and the primary plan pays $700, the secondary plan may cover part or all of the remaining $300.

Even with both primary and secondary insurance, there might still be some out-of-pocket expenses. The secondary plan will only pay for services that are covered under its own policy terms. The process involves submitting the claim to the primary insurer first, waiting for their explanation of benefits (EOB), and then submitting the claim along with the EOB to the secondary insurer.