That’s when the facility requires you to sign a document that sez if Medicare or your insurance company doesn’t pay your responsible. (More)-In healthcare, an ABN, or Advance Beneficiary Notice, is a written notice that a healthcare provider gives to a patient before providing a service that Medicare may not cover. It essentially informs the patient, in advance, that they may be held financially responsible for the cost of that service if Medicare denies the claim.

Nothing to add to the other comments. The provider is required to have you sign that form in order for you to be responsible for the charges.