That is correct – you would have to qualify medically to change from hdG to regular G. A physical is not required, but you have to answer medical questions on an application and the company would review your electronic medical records and possibly do a phone interview to determine whether or not you are “approved”. The open enrollment period you referenced – assuming you are referring to the Oct 15-Dec 7 annual election period – is just for Part D (drug coverage) plans and does not apply to Medigap plans at all. After your initial 6-month period when you turn 65 or start on Part B for the first time, there is not an open enrollment for Medigap. Hope this helps – let me know if you have other questions!

Thanks for taking the time to comment! You may be confusing the high deductible Plan F, which is the plan for people who turned 65 before 2020. The high deductible Plan G, is only available to people new to Medicare after 1/1/2020. Medicare is not a good resource for Medigap information since they don’t oversee those plans, but this page on the Medicare website, specifically the note under the chart, explains: https://www.medicare.gov/health-drug-plans/medigap/basics/compare-plan-benefits. And this CMS press release details again: https://www.cms.gov/medicare/health-drug-plans/medigap/f-g-j-deductible-announcements#:~:text=High%20deductible%20Plan%20G%20is,or%20after%20January%201%2C%202020. Definitely can’t rely on Reddit Medicare or Bogleheads for accurate/complete Medicare information.