1 Preventive services. 2  Medicare Part B helps pay for a number of tests, screenings, vaccinations, and a one-time physical exam to help you stay healthy. 3  Many of these services are available at no cost at the time of the visit.ou’ll pay a lifetime 10% penalty for every 12 months you delay your enrollment. 1  Medical and other services. 2  Medicare Part B pays 80% of most doctor's services, outpatient treatments, and durable medical equipment (like oxygen or wheelchairs). 3  You pay the other 20%.