Question: Answer: Billing would primarily depend upon whether the provider is "participating" or "non-participating" with Medicare. Private insurances could have their own rules. If it is a Medicare patient and your practice has agreed to be a "participating supplier" with Medicare, then the practice must accept the Medicare payment amount for the item. Even if a "participating supplier" gets an ABN signed, that still would not allow them to charge more than Medicare is willing to pay. Here is a link to a document that explains this: www.medicare.gov/publications/pubs/pdf/11045.pdf . If it's a private insurer, then billing would depend on that insurer's rules and state laws, and they vary widely. Contact a health care attorney in your state to be sure.