Medicare Advantage
A second Medicare Advantage window for Missoula enrollees
MISSOULA, Mont. — For Montanans already enrolled in a Medicare Advantage plan, the calendar just opened a second chance. From January 1 through March 31, the Medicare Advantage Open Enrollment Period gives current enrollees one more window to change course if the plan they picked in the fall isn't working out.
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Key takeaways
- The Medicare Advantage Open Enrollment Period runs January 1 through March 31 and is only for people already enrolled in a Medicare Advantage plan on January 1.
- During this window you can switch to a different Medicare Advantage plan or drop your plan and return to Original Medicare, with a chance to add a stand-alone Part D drug plan.
- You get one change during this period — not unlimited swaps — and it takes effect the first of the month after the plan receives your request.
- If you miss March 31, your next regular opportunity is the Annual Enrollment Period, October 15 through December 7, unless you qualify for a Special Enrollment Period.
It's a narrower door than the fall Annual Enrollment Period, and it comes with its own rules. Missing the March 31 deadline usually means waiting until next fall to make another move.
Who this window is actually for
The January–March window is often confused with the fall Annual Enrollment Period. They are not the same.
The Medicare Advantage Open Enrollment Period is only for people who are already in a Medicare Advantage plan as of January 1. If you're on Original Medicare on New Year's Day, this window does not let you jump into a Medicare Advantage plan. You would need to wait for the fall or qualify for a Special Enrollment Period.
If you enrolled in Medicare Advantage for the first time during the fall and your new plan started January 1, you are eligible to use this window to change your mind.
What you can — and can't — do between Jan. 1 and March 31
Inside this window, you can:
- Switch from one Medicare Advantage plan to another Medicare Advantage plan.
- Drop your Medicare Advantage plan and go back to Original Medicare (Parts A and B).
- If you return to Original Medicare, join a stand-alone Part D prescription drug plan.
You cannot:
- Move from Original Medicare into a Medicare Advantage plan for the first time.
- Join or switch a stand-alone Part D plan if you're staying on Medicare Advantage with drug coverage.
- Make more than one change. This period gives you one switch, not a series of do-overs.
Any change you make becomes effective the first day of the month after the plan gets your enrollment request.
Why the deadlines matter more than the choice
The dates are strict. According to CMS, the Medicare Advantage Open Enrollment Period ends March 31 with no automatic extension. If your new plan isn't a good match, the calendar — not the plan — decides how long you're stuck with it.
Here's how the windows fit together:
- Oct. 15 – Dec. 7: Annual Enrollment Period. Anyone with Medicare can join, switch, or drop Medicare Advantage or Part D coverage. Changes take effect January 1.
- Jan. 1 – March 31: Medicare Advantage Open Enrollment Period. One change allowed, for current Medicare Advantage enrollees only.
- Anytime: Special Enrollment Periods can open if you move, lose other coverage, qualify for Extra Help or Medicaid, or fall into certain other categories.
Missing all three usually means waiting until the next fall enrollment window to adjust your coverage.
A few scenarios Missoula readers ask about
"I switched plans in December and my doctor isn't in the new network." You can use the January–March window to change to a different Medicare Advantage plan, or drop back to Original Medicare and pick up a stand-alone Part D plan.
"I want to leave Medicare Advantage and go back to Original Medicare." You can do that now. Keep in mind that if you want a Medicare Supplement (Medigap) policy to go with Original Medicare, medical underwriting rules may apply outside your initial Medigap enrollment window. Call your State Health Insurance Assistance Program (SHIP) before you drop coverage.
"I'm on Original Medicare and want to try Medicare Advantage." This window isn't for you. Mark October 15 on your calendar, or check whether you qualify for a Special Enrollment Period.
The local picture
Missoula is in Missoula County, where Medicare Advantage plan availability is set at the county level. The exact list of plans, along with each plan's benefits, network and drug formulary, is on the Medicare Plan Finder at medicare.gov. That is the tool CMS points to for accurate, side-by-side comparisons in your ZIP code.
If you'd rather talk to a human, Montana's SHIP program — through the State Health Insurance Assistance Program — offers free, unbiased counseling.
By the numbers
Medicare Part B premium, 2006–2026
The standard monthly Part B premium has climbed from $88.50 in 2006 to $202.90 in 2026. Hover any point for that year’s premium.
Source: CMS. Standard premium shown; in some hold-harmless years many existing enrollees paid less. Confirm at Medicare.gov.
By the numbers
How people get Medicare in Missoula County
(MA penetration in Missoula County)
MA penetration from CMS enrollment data; Medigap share is an estimate. U.S. average is about 54% Medicare Advantage. These are area-level figures, not plan-specific.
Key dates
Medicare enrollment periods at a glance
- Around your 65thInitial Enrollment PeriodA 7-month window around the month you turn 65 — your first chance to sign up.
- October 15 – December 7Annual Enrollment PeriodAnyone with Medicare can join, switch, or drop a Medicare Advantage or Part D plan.
- January 1 – March 31Medicare Advantage Open EnrollmentIf you're already in a Medicare Advantage plan, you can make one change.
- January 1 – March 31General Enrollment PeriodFor people who missed their first chance to sign up for Part B.
- VariesSpecial Enrollment PeriodTriggered by life events like moving or losing other coverage.
Dates are set by Medicare and apply nationwide. Confirm your personal windows at Medicare.gov or 1-800-MEDICARE.
Explore
When can you enroll? An interactive year
Enrollment windows are federal and the same nationwide. Confirm your personal dates at Medicare.gov or 1-800-MEDICARE.
Explore
The parts of Medicare
Good to know
Frequently asked questions
Can I join a Medicare Advantage plan for the first time between January and March?
How many changes can I make during this window?
When does my new coverage start?
What if I miss the March 31 deadline?
- CMS — Medicare enrollment periods (medicare.gov)
For personalized answers, contact Medicare.gov, 1-800-MEDICARE, or your local SHIP.
Also for Missoula
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This page was last updated: September 2026.