Final answer:
In an ABN, the cost estimate should be within $100 or 25 percent of the actual cost. The ABN serves to inform Medicare beneficiaries about services not likely covered and helps them decide on receiving the service.
Step-by-step explanation:
When presenting a cost estimate on an Advance Beneficiary Notice of Noncoverage (ABN) for a potentially noncovered service, the cost estimate provided to the beneficiary should be within $100 or 25 percent of the actual cost. The ABN is a notice given to beneficiaries in Medicare to convey that Medicare is not likely to provide coverage for a specific medical service or item. The cost estimate assists beneficiaries in making informed decisions about whether to receive the service or item and accept potential financial responsibility.