OH, WHY, OH, WHY Did you not get Part B when 1st eligible ESPECIALLY if you were planning to come back to the states.? Part B premiums pay for 25% of the Part B total cost of the program each year - it's insurance - you pay premiums for it regardless of whether or not you use it in any given year. You cannot just sign up for it after this long of time and not have to pay your dues.
You maybe in for a big ($$$$$) surprise when you sign up for Part B since you are WAY LATE signing up for Part B. There is gonna be a hefty Part B late sign-up penalty.
Medicare.gov - When Does Medicare Coverage Start
Medicare.gov Part B late enrrollment penalty
In fact, you may want to go ahead and sign up to avoid even MORE Part B late sign-up penalty.
Then there is the Part D they you will also have to get (and there will be more late sign-up penalty there too).
What Does Medicare Cost?
In fact, you may want to give Medicare a call and get the actual premium cost (including penalty) to see if you really want to even use it or even come back.
If you do want it, you may need to talk to Medicare about when to start the process and your effective date cause it is probably gonna take awhile to get it set up since it will involve going back and calculating the penalty from year to year.
AARP.org - How Much is the late Enrollment Penalty for Part B
The Balance - Current and Past Medicare Part B Premiums
This link will give you the standard Part B premiums through the years - the penalty is cummulative.
Sorry - It is what it is -
It's Always Something . . . . Roseanna Roseannadanna