Remember, if you chose an Advantage plan, you cannot change over to a Supplement Plan in the future without a physical, a health review, etc. You may be turned down.
This is fundamentally correct however there are exceptions. Most should assume once in Advantage always in Advantage unless you meet one of the exceptions below.
1. If new to Medicare and choose an Advantage Plan you can switch back to traditional medicare in your first year without underwriting/guaranteed placement. Its called a trail period.
2. In a limited number of states they allow you to switch back without underwriting and guarantee going back to Medicare
3. If your current Medicare Advantage plan is not going to be offered the following year, you can select another Advantage plan or GO back to Traditional Medicare with guaranteed acceptance.
4. If you move to another area that your Advantage plan is not offered you can chose another or go back to Medicare
Note: Medicare Advantage plans are one year contracts for medical insurance. It will automatically renew at the end of that year if the plan is still offered. Also at that time of year you can switch out to another Advantage plan if you wish.
There is the annual enrollment period of October 15th to Dec 7th of each year.
There is a second period Jan 1st to March 31st of each year that if you are unhappy with the Advantage plan you chose you can switch to another Advantage plan.
To
@ZZman - you dont mention your state but BCBSNC offers a deal that if you have one of their Advantage plan they will allow you to switch to a BCBSNC Medigap plan. They market themselves as Blue to Blue. Im sure this is unique to the state of North Carolina. As I know of no other company that allows this.
BTW- CONGRATULATIONS Turning 65. It is no secret that I love the Medicare system. Far more protections than any company health insurance. I had an Advantage plans for 3 years. 2 years with UHC and 1 Year with Aetna. Not once did I have a complaint with them. Aetna was not going to offer the plan I had in 2024 for 2025 so with a fresh diagnosis of cancer in late 2024 that Aetna paid all expenses for while being diagnosed without question nor hesitation which included PSMA Pet Scans, hours long meeting with a panel of doctors at Duke Cancer Clinic and gosh a handful of other specialists near the coast where I live. NOT one hold up or question.
I went back to Medigap Plan N for 2025. For 2026 I am going back to Advantage with Humana. The reason I went back to Medicare and Plan N is at the time to change plans from October to Dec 7th I had no idea where I was going to be treated and being new to the area in a new home. I had no clue as the networks here. Plus the cost was similar, paying the extra 150 a month vs the Advantage with MOOP. Im actually excited about having the perks of the Advantage again.
Good luck to you! Best wishes for your wife. Life is precious which becomes more apparent as we get older.
Enjoy retirement, my only regret about retiring is not being rich enough to retire when I was 30. 
