What are the general co-payment responsibilities under Medicare Part B?

The correct choice identifies that beneficiaries are typically responsible for a 20% co-payment for most services covered under Medicare Part B, after they have met their deductible for the year. This co-insurance means that Medicare will cover 80% of the approved amount for services, and beneficiaries are responsible for the remaining 20%.

Medicare Part B covers medically necessary services, which may include doctor visits, outpatient care, preventive services, and certain types of durable medical equipment. The deductible must be satisfied before the co-payment applies, ensuring that beneficiaries share in the cost of their healthcare beyond just paying premiums.

The other choices describe scenarios that do not align with the standard co-payment structure of Medicare Part B. No additional costs after premiums would imply full coverage without shared financial responsibility, which does not reflect the cost-sharing model of Medicare. A flat fee for all out-of-pocket costs misrepresents the graduated way that costs can vary by service, and full payment required at the time of service does not apply because Medicare typically bills beneficiaries after services are rendered, allowing for the insurance to pay first.