Understanding the correct use of the Advance Beneficiary Notice of Noncoverage (ABN) Form CMS-R-131 is important to ensure billing compliance for traditional Medicare (Part B). Audiologists may face challenges determining when Medicare covers a service and when an ABN is required. Federal law requires that providers, including audiologists, must notify a Medicare beneficiary in advance when a service that Medicare typically covers is likely to be denied and/or when the item or service is not considered by Medicare to be medically reasonable and necessary. The ABN meets this requirement.