Which of the following is considered cost sharing by the beneficiary?

Coinsurance is a term that refers to the portion of healthcare costs that a beneficiary is responsible for paying after meeting their deductible. In a typical Medicare plan, after the beneficiary has paid their deductible, they may need to pay a certain percentage of the costs for covered services. This arrangement signifies the sharing of costs between the insurer and the insured, and thus is classified as a form of cost sharing by the beneficiary.

Premiums represent the monthly fees that beneficiaries must pay to maintain their Medicare coverage. Supplemental insurance, also known as Medigap, refers to additional insurance that covers costs not fully paid by Medicare. Lifetime limits, which are caps on the total benefits that can be paid out over a beneficiary's lifetime, are not directly related to cost sharing but rather reflect the limitations of insurance coverage. Each of these other factors affects overall costs and coverage but does not constitute the beneficiary's direct out-of-pocket responsibility in the way that coinsurance does.