Wiki Birthday Rule

[CGephart]

If you have a married couple who have a baby. The mother covers the child on her insurance. The father does not cover the child with his insurance.
Is the fathers insurance still primary for the first 31 days of the child's life. (the father's birthday is before the mother's)

 

[RebeccaWoodward*]

If the mother, and only the mother carries insurance, this will be the primary plan. It's when both parents carry insurance that the "birthday rule" applies. Under this rule, the plan of the parent whose birthday occurs earliest (month and day) in the year is the primary plan for dependent children (in typical circumstances).