Why it matters
When a child is covered under both parents' plans, the birthday rule (not the older parent's age) usually determines which plan pays first -- confirming this early avoids claim delays.
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Birthday Rule
The birthday rule is a common coordination-of-benefits rule that decides which parent's health plan is primary for a dependent child: whichever parent's birthday falls earlier in the calendar year.
Example
If one parent's birthday is in March and the other's is in September, the March birthday's plan is typically primary for the child, regardless of which parent is older.
Common mistake
A common mistake is assuming the parent's age, rather than birth month and day within the calendar year, determines which plan is primary.
Quick comparison
| Topic | Birthday Rule |
|---|---|
| Coverage area | health |
| Best next step | Review how this term applies to your plan, state, timing, and coverage question. |
Questions about Birthday Rule
Why should I understand Birthday Rule before calling?
Understanding Birthday Rule helps you describe your question clearly, compare tradeoffs, and avoid focusing on only one number when a licensed review may need more context.
Can Birthday Rule change by plan or policy?
Birthday Rule can vary by carrier, plan type, state, network, timing, and policy language, so use this explanation as education rather than a personal coverage decision.
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Information on this site is educational and does not guarantee eligibility, enrollment, pricing, or availability. It is not a recommendation to buy any specific plan or policy.