Part D is prescription drug coverage which is optional. You can choose from multiple plans that run from about $15/month up to ... $50(?) depending on a number of variables. Part D is optional only if you never take advantage of it. And if you do some day take advantage of it, there is a time-based penalty you must pay. It's in the Medicare booklet. Look it up. It's not something they scream and yell about.
I had Aetna last year at $27/mo. This year they went up to $64/mo. Guess who switched to Walart/Humana at $14.97/mo? Not as nice a plan but better than $64/mo. Especially since, thank the Good Lord, I have no non-generic prescriptions.
It's in the Medicare booklet. Look it up. Yes, I was aware of the penalty for taking the Part D option after originally declining it.
I'm not due for MC for almost two years, but decided to investigate during our long winter days.
It's confusing as hell, but quite frankly the
gov't website does a pretty good job.