We had a patient come in for partial hospitalization and an intensive outpatient treatment program for alcohol. They had a Health Net plan and we obtained precertification for the treatment. The claims recently denied as "not a covered service" due to the policy being a Medicare replacement plan which neither the patient or insurance told us about. The insurance is saying the codes are not covered by Medicare. We don't take Medicare and are unfamiliar with Medicare facility codes for MH and substance. The revenue codes for partial and IOP are 0912 and 0906 respectively and the HCPCS are H0035 and H0015 both of which are being denied. Although the insurance plan and the Medicare billing manual say substance abuse treatment is covered, we can't find anyone who knows the actual codes Medicare uses. Would any one here in this forum be familiar with these Medicare codes? Thank you.