Part D is provided by multiple entities and the formularies are different for each. You need to compare your medication usage against the various plans to see which provide the drugs you use. You can make changes yearly during open season with no underwriting. Part D is not required if you have access to other creditable coverage such as a spouse’s plan, an employer, military, VA, etc. and there are no penalties incurred in those situations if you opt not to get a Part D plan. There is also no penalty if you need to switch to Part D at a later date due to loss of your current coverage.
I would like to amplify on this by noting when there IS a penalty, a life time one every month.
That is in the case where you cease to have a plan D or something that the government considers to be equivalent. After a certain lapse period, the penalty goes up for each month you went without.
As I’ve posted before, it is worth going to a senior center or other non-profit service to help pick a plan (or run the Med D formula yourself). I review my plan each year.
Several years ago, a senior center person recommended leaving out an expensive eye drop from the Med D formula and buying that one outside Med D using GoodRX. I got a much cheaper premium and, for whatever reason, it was cheaper to buy the eye drop outside of Med D, using GoodRX. Others, such as Mark Cuban, might also be cheaper.