Lower out-of-pocket costs for Medicare beneficiaries.

As one of the Trump administration’s major drug price initiatives, this proposal aims to reduce the costs that many older residents face at the pharmacy. Medicare consumers are often forced to pay out-of-pocket costs based on a list price, even when — behind the scenes — private pharmacy benefit managers have negotiated bigger discounts, or rebates, with the manufacturer.

The Trump administration’s plan would eliminate the legal protections for rebates, and require discounts to be passed along to consumers. Alex M. Azar II, the health and human services secretary, has said he hopes the change will simplify a broken system and give manufacturers an incentive to lower their list prices.

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But the true impact of the rule is far from clear, and the change could raise costs in other parts of the chain. While it would save some people money on out-of-pocket expenses, it is expected to raise drug-plan premiums for all Medicare beneficiaries, and it also would quite likely cost the federal government money. The nonpartisan Congressional Budget Office concluded in May that the rule, if adopted, would cost taxpayers $177 billion within 10 years.

The rule is also unusual because — unlike many other proposals to bring down drug costs — it is supported by the pharmaceutical industry, which has put part of the blame for rising prices on pharmacy benefit managers. Insurers and pharmacy benefit managers say the rule would stymie their ability to effectively negotiate with drug makers.

The Trump administration has signaled that it is likely to finalize the rule some time this year.

Cap out-of-pocket spending under Medicare.

The drug coverage program known as Part D, for those who are 65 and older, has no limit on out-of-pocket spending. People who need expensive drugs (such as for cancer treatments or other serious diseases) can wind up paying thousands of dollars.

In addition, once a patient’s drug spending reaches a certain level in a year — $5,100 in 2019 — the federal government picks up most of the bill, rather than the private insurers who operate the drug plans.