For most Medicare Advantage enrollees, it allows the individual to make one switch to either another Medicare Advantage plan or back to Original Medicare during that window.  MSA plans are Medicare Advantage products; however, CMS excludes MSA plans from the OEP, whether entry or exit from the MSA plan.  The rationale is all around the front loaded annual deposit.  The full deposit amount occurs the first week in January and then if CMS allowed that same individual to pick another plan option, recouping those funds would be very challenging.  CMS is not willing to take the financial risk and therefore does not allow individuals to enter or exit MSA plans during OEP.