Final answer:
Providers must obtain an Advance Beneficiary Notice of Noncoverage prior to providing a service or item that Medicare is not expected to cover.
Step-by-step explanation:
Providers are responsible for obtaining an Advance Beneficiary Notice of Noncoverage (ABN) prior to providing a service or item to a beneficiary that is not considered medically necessary. So, the correct answer to when providers are responsible for obtaining an ABN is 3) Prior to providing a service or item to a beneficiary. An ABN is a written notice given to Medicare beneficiaries to convey that Medicare is not expected to provide coverage for a specific medical service or item, thus making the beneficiary responsible for payment should they choose to receive the service or item.