You can bill the 3rd party insurance, but the funds ALWAYS go to the patient and then only after the claim has been settled. That often takes years. Your best option is to encourage the patient to use their own Auto insurance if they have Med Pay, then the two insurance companies will square up when the claim is finished. The patient shouldn't have an out of pocket, and you'll get paid faster.If they use their health insurance, all deductibles and co-pays still apply. Their health insurance will recoup anything they paid out when the claim settles.