Dear Medicare Applicant,
According to the SSA website, Part A can go retro-effective 6 months. I would think Part B is the same and it should go back to December 1, 2015. Is United Health your medicare provider? If you can during the next sign up date, use the traditional, pure medicare, the coverage is best beneficial under this choice in general. It is with the minimum limitations in general. Of course, everyone needs to get supplemental insurance to get complete coverage. I hope this answer your question and please feel free to follow up with your question. Otherwise, I am ready to be rated by you for your satisfaction of my answer to your question. See link and quotation below please. Thank you.
Fiona Chen, MPA, Ph.D., CPA, ABV, CFF, CITP
You can sign up for free Part A (if you’re eligible) any time during or after your Initial Enrollment Period starts. If you sign up within 6 months of your 65th birthday, your coverage will start the first day of the month you turn 65, or the month before you turn 65 (if your birthday is ***** first of the month). After that, you’re coverage start date will go back (retroactively) 6 months from when you sign up.