Medicare beneficiaries can enroll directly through the plan's sponsor, or indirectly via an insurance broker or the exchange—called Medicare Plan Finder—run by the Centers for Medicare and Medicaid Services (CMS) for this purpose; the beneficiary's benefits and any additional assistance payments and rights are the same regardless of enrollment channel. Beneficiaries already on a plan can choose a different plan or drop Part C/D during the annual enrollment period or during other times during the year under special circumstances. For some time, the annual enrollment period has lasted from October 15 to December 7 of each year but that is changing for Part C in 2019. In particular, low-income seniors on Social Security Extra Help/LIS and many middle-income seniors on state pharmaceutical assistance programs can choose a different plan or drop Part C/D more often than once a year.