I'm happy with my existing prescription drug plan and it is "creditable" - what should I do?
You may wish to simply stay with your current plan.
Because your plan is creditable, you can always decide later to join a Medicare Part D plan without paying an increased premium. During the open enrollment period, each year from October 15 through December 7, you may want to reevaluate your options and decide then which alternative is economically and practically most advantageous.