I am not an insurance agent or financial planner, just a pancan patient. It's my understanding that if you're moving from Medicare Advantage (part C) to traditional Medicare (parts A/B), you will undergo underwriting in order to obtain a supplemental Medigap policy. Companies are NOT required to issue a Medigap policy to you. If you can't get the supplemental, that means that all copays would be on your nickel. Obviously, with an active cancer diagnosis, making it through underwriting would be impossible. But you're right, open enrollment is under way, so now is the time to ask questions.

If anyone out there is getting ready to move onto Medicare, I am an advocate for starting with traditional and a supplement rather than Advantage. Please examine your options carefully. I can tell you that in late 2020, I landed in the hospital for three months with cardiac issues likely related to covid. My bill was $1.7 million; I paid less than $100 out of pocket. So far this year, I've had multiple surgeries and lots of chemo, scans, MD visits and such. I've paid only my original deductible. For us, the higher monthly premiums are definitely worth it.