it looks like you meant to say patient OR the insurance company. What I would look at first is the charge, the posted amount and the write off. If its an insurance credit, that can only happen if someone adjusted too much off, or the insurance company double paid and you need to refund the money especially if its medicare/medicaid/tricare
if its a patient credit, (providers HATE to give refunds), you should determine why the patient also has a credit. In my experience this usually happens when the incorrect copay is received. Before you refund the patient check to see who has been there. If a patient hasn't been seen since 2004 you should definitely try to reach them to refund the money. You just can't make it "disappear" For those that are true credits and are being seen often, you can still contact them, but its just as easy to not take the next visit copay (which should have happened anyway) so that the credit can be applied to that visit. Most of our clients preferred to keep the credit since they generally came for thier check ups and follow up visit.