Hopefully the below helps answer some questions you may have.
May 5, 2020, the Centers for Medicare and Medicaid Services (CMS) announced that the Special Enrollment Period (SEP) they have for beneficiaries affected by a FEMA-declared weather-related emergency or other major disaster is now applicable for COVID-19. This SEP is particularly for people who missed an opportunity to change their Medicare Advantage and/or Part D plans due to the COVID pandemic this spring. We have not yet heard about an official SEP for beneficiaries who missed their SEP to enroll in Medicare Part B after stopping work, or who missed enrolling in Part B during the annual General Enrollment Period from Jan 1 through Mar 31 each year. (Update 5/6/20: CMS now also granted equitable relief for those unable to enroll in Part A or B of Medicare due to COVID-19 related lack of access to Social Security. )
This SEP is available nationwide to beneficiaries of all states,
tribes, territories, and the District of Columbia effective March 1, 2020 and
runs through June 30, 2020.
Again, to be eligible for this SEP for MA and Part D plans, a beneficiary must have been unable to make a change to their coverage during a valid election period as a result of the COVID pandemic. This includes enrollments and dis-enrollment's.