CardsFan
Thinks s/he gets paid by the post
You can no longer enter plan F or F-HD starting 1/1/2020. So if you DH retires on 12/31 and needs insurance beginning the next day, Plan F or F-HD are not any of your choices. That is if he is first eligible for Medicare on that date.
Not sure this 100% correct. As I understand there are some exceptions. I believe one exception is if you Medicare eligible prior to 2020, but covered on an employer plan, you may still have the ability to enroll in Plan F.
So, if meleana's DH will be 65 before the end of this year, he may be able to enroll in F. If not, then you are correct and Plan F is not an option.