Short answer: Not the way they used to. Since 2025 the quarterly window is gone; instead, someone with Medicaid or Extra Help can join or switch a standalone Part D plan once per calendar month, which can also take them out of Medicare Advantage back to Original Medicare. It is not a monthly right to switch from one Medicare Advantage plan to another.
CMS’s contract year 2025 rule replaced the old quarterly special enrollment period for dual eligibles and Extra Help enrollees with a once-per-month SEP to enroll in a standalone prescription drug plan. The regulation (42 CFR 423.38(c)(4)) limits it to a one-time-per-month election into a PDP.
Medicare.gov describes what the person can do with it:
- Join or switch to a different Medicare drug plan.
- Drop a Medicare Advantage plan with drug coverage and return to Original Medicare by joining a standalone drug plan.
- The change takes effect the first day of the next month.
It isn’t available to someone the plan has identified as a potential at-risk or at-risk beneficiary under a Part D drug management program. Moving into a Medicare Advantage plan mid-year needs another window, such as the integrated D-SNP SEP for full duals.