My cardiologist office opted out of Medicare but there are 3 participating providers in that practice that takes these commercial insurances like BC/BS, Aetna, Cigna, UHC and Oxford secondary. Our office is accepting assignment with Medicare because of the participating secondary carrier. We are getting denials from the secondary insurance that there's no patient responsibility after Medicare denial. When we are submitting our claims, do we accept assignment on the claim so we can submit to secondary assigned as a primary carrier or do we not accept assignment because we opted out of Medicare so Medicare leaves a patient responsibility to submit to participating secondary carrier unassigned and process as primary carrier. Please help us in what we are doing wrong.