When a child is covered by both parents’ health plans, the birthday rule for child health insurance decides which policy pays first: the parent whose birthday falls earlier in the calendar year holds the primary plan, and the other parent’s plan is secondary.1Virginia Code Commission. 1VAC55-20-430 The rule looks at month and day only. The birth year does not matter, and neither does which parent earns more or has the better benefits.
How the Birthday Rule Decides the Primary Plan
Insurers use a set of rules called coordination of benefits to sort out the order of payment when a dependent is on more than one plan.2Connecticut Office of the Healthcare Advocate. Coordination of Benefits (COB) For a child covered by both parents who live together, the birthday rule is the standard tie-breaker. Compare the two birthdays by month and day. Whichever parent’s birthday lands earliest in the year provides the primary coverage. The other parent’s plan sits in the secondary spot.1Virginia Code Commission. 1VAC55-20-430
A parent born on March 12 with a spouse born on September 4 holds the primary plan for their child, regardless of who carries the more generous policy. A parent born on January 30 whose spouse was born on January 8 is secondary, because January 8 comes first.
When Both Parents Share a Birthday
If both parents were born on the same month and day, insurers fall back on a length-of-coverage tie-breaker. The plan that has covered a parent for the longer period is treated as primary for the child.3Illinois General Assembly. 50 Ill. Adm. Code 2009.40 – Section: (b) Dependent Child/Parents not Separated or Divorced
How Primary and Secondary Coverage Pay Together
The primary plan processes the claim first and pays its share. The secondary plan then reviews what is left and may cover some or all of the remaining eligible expenses. Coordination of benefits caps the combined payments so that both plans together do not pay more than the total allowable cost of the service.2Connecticut Office of the Healthcare Advocate. Coordination of Benefits (COB) How each plan treats deductibles and maximums under secondary status varies, so it’s worth checking your policy documents directly.4Ohio Legislative Service Commission. Ohio Admin. Code 3901-8-01 – Section: (C) Definitions
When the Birthday Rule Does Not Apply
Divorce, legal separation, and custody arrangements change the order of payment. In those situations, legal documents or specific policy terms take priority over the birthday-based order.1Virginia Code Commission. 1VAC55-20-430
If a court order names the parent responsible for providing the child’s health insurance, insurers follow that order to determine the primary plan. When no court order addresses coverage, the plan of the parent with primary physical custody is usually treated as primary. Send a copy of the divorce decree or custody agreement to both insurers so the correct rule is applied from the start.1Virginia Code Commission. 1VAC55-20-430
Joint custody works the same way. If the court order specifies which parent’s plan is primary, insurers follow it. If the order is silent, insurers fall back on the birthday rule or the length-of-coverage tie-breaker.1Virginia Code Commission. 1VAC55-20-430
Making Sure the Rule Works for Your Family
Two practical steps keep the coordination of benefits process running smoothly.
First, enroll the child on both plans within the required window. Federal law requires employer-sponsored health plans to offer a special enrollment period of at least 30 days after a child is born or adopted. Miss that window and the child may not be covered at all, which shuts down any coordination of benefits before it starts.5Office of the Law Revision Counsel. 29 U.S. Code § 1181
Second, read the coordination of benefits section in each plan’s documents. That section spells out exactly how the insurer handles a dependent covered under more than one policy, and confirming it in writing avoids surprises when a claim is filed.2Connecticut Office of the Healthcare Advocate. Coordination of Benefits (COB)