What is "The Birthday Rule" in Health Insurance?

Like many dual-income couples, you and your spouse may have both included your kids on each of your group health insurance plans. However, without some sort of system in place to help the insurance companies coordinate benefits, it's possible that either you or your doctor would be reimbursed for more than 100 percent of the actual cost of your claim.

To prevent this, insurance companies typically designate one parent's health insurance plan as the primary plan and the other as the secondary plan. The primary plan is responsible for paying covered expenses up to the limits of the policy. If any unpaid costs are left over, the secondary coverage kicks in.

The birthday rule is often used to determine which health insurance plan is primary. Under this rule, the health insurance plan of the parent whose birthday occurs first in the calendar year is designated as primary. The date of birth is the determining factor, not the year, so it doesn't matter which spouse is older.

The birthday rule has exceptions:
If both parents share the same birthday, the parent who has been covered by his or her plan longest provides the primary coverage for the children.

If one spouse is currently employed and has health insurance through a current employer, and the other spouse has coverage through a former employer (e.g., through COBRA), the plan belonging to the currently employed spouse would be primary.

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