Annual Enrollment Period: October 15 to December 7
Every fall, anyone with Medicare can join, switch or drop a Medicare Advantage plan or a Part D drug plan, or move between Original Medicare and Medicare Advantage. The last choice you make by December 7 is the one that starts January 1. Plans change their costs, benefits, drug lists and networks each year, so read the Annual Notice of Change your plan sends in September before you decide. See enrollment periods.
Medicare Advantage Open Enrollment Period: January 1 to March 31
If you're in a Medicare Advantage plan on January 1, you can make one change by March 31:
- Switch to a different Medicare Advantage plan, or
- Drop Medicare Advantage, go back to Original Medicare, and join a Part D plan.
The change starts the first of the following month. This window isn't for people with Original Medicare who want to join Medicare Advantage, or for switching from one standalone Part D plan to another. People new to Medicare Advantage get the same option during their first three months of Medicare.
Special Enrollment Periods
Certain events let you change coverage at other times. Common ones in Arizona:
- Your plan is leaving your area. When a plan doesn't renew its contract with Medicare, you can choose new coverage from December 8 through the last day of February of the following year, on top of the Annual Enrollment Period. See plans ending in 2027.
- You move. If you move out of your plan's service area, or move permanently to Arizona, your window starts the month you move and lasts two full months after.
- You have AHCCCS or Extra Help. You can make changes to your drug coverage once a calendar month, with the change starting the first of the next month.
- You lose job-based coverage. You have two full months after the month your employer or union coverage ends, including COBRA, to join a Medicare Advantage or Part D plan.
Plan leaving for 2027? If you take no action, you'll be in Original Medicare on January 1 without drug coverage unless you join a Part D plan. Check the letter from your plan and your options before December 7, 2026 if you can.
What about Medigap?
Medigap policies aren't tied to the Annual Enrollment Period. You can apply any time, but outside your Medigap open enrollment period or a guaranteed-issue right, the company can use your health history. Leaving a Medicare Advantage plan that is ending in your county gives you a guaranteed-issue right. See when you can buy Medigap in Arizona.
Get help
A licensed insurance agent with Benefits Life can review your options and compare plans from the companies they work with, at (602) SENIORS (602-736-4677), TTY 711. You can also see plans in your ZIP code.
Related questions
When can I buy Medigap in Arizona?
Open enrollment and guaranteed-issue rights.
Can snowbirds keep their Medicare plan?
The six-month rule and moving to Arizona.
Does AHCCCS pay Medicare premiums?
Medicare Savings Programs and the monthly change option.
Sources
- Medicare.gov — Joining a health or drug plan
- Medicare.gov — Special Enrollment Periods
- Medicare.gov — Understanding Medicare Advantage and Medicare drug plan enrollment periods
- Medicare.gov — When can I buy Medigap?
- CMS — Medicare Advantage and Part D plan data (2027 Landscape files)
Frequently asked questions
My Medicare Advantage plan is leaving my county for 2027. What can I do?
You can choose a new plan during the Annual Enrollment Period, through December 7, 2026. If you don't, a Special Enrollment Period lets you pick a new plan from December 8 through the last day of February 2027. If you take no action, you'll have Original Medicare on January 1, and you also have a federal right to buy certain Medigap policies without health questions.
Can I switch Part D plans in the middle of the year?
Usually not, unless you qualify for a Special Enrollment Period. People with AHCCCS or Extra Help can change once a calendar month, and moving out of your plan's area or losing other drug coverage also opens a window.
Can I go back to Original Medicare after the AEP?
If you're in a Medicare Advantage plan, you can switch to Original Medicare and join a Part D plan during the Medicare Advantage Open Enrollment Period, January 1 to March 31. Buying a Medigap policy then may require answering health questions unless you have a guaranteed-issue right.
Can I change my Medigap policy any time?
You can apply for a different Medigap policy at any time, but outside your Medigap open enrollment period or a guaranteed-issue right, the company can ask health questions and turn you down or charge more. Medigap isn't part of the Annual Enrollment Period.
