From January 1st to March 31st, individuals enrolled in Medicare Advantage, also known as Part C, can switch to a new Medicare Advantage plan or can leave the program altogether and return to Original Medicare (Parts A and B, with the option of buying a stand-alone Part D drug plan). Typically, this window closes February 14th, but this year the open-enrollment period has been extended through March 31st. Each eligible person is allowed only one change during this period. One reason someone might opt for a new plan, or switch out of Medicare Advantage altogether, is if he/she discovers that one of his/her doctors doesn’t participate in the plan, or if he/she wants to see a specialist the plan won’t pay for. Another reason is that reimbursements for drugs might be better under one plan that another.
Source: Money.com, March 2019