Federal health officials said they will soon address growing concerns about the lucrative commissions that some Medicare insurers plan to pay their agents and brokers this year. Documents obtained from some companies participating in Medicare Advantage show that their agents stand to make $500 to $550 this year for enrolling a beneficiary into one of their plans. In subsequent years, the agents could make another $500 for every year the beneficiary stays with the plan. After five years, an agent could have made more than $2,500, a big jump from previous years.