When Does Medicare Part D Drug Coverage Begin?

By Patricia Barry

Copyright © 2018 by AARP. All rights reserved.

Your Medicare Part D drug coverage doesn’t start until the date it becomes effective, meaning the very first day you can fill a prescription under your Part D plan, even if you receive your membership card in the mail before then. In most situations, you don’t have to wait long. Coverage begins on the first day of the month after you sign up with a Part D plan during your initial enrollment period or during any special enrollment period.

The only variation here is if you enroll in a Part D plan during open enrollment (October 15 to December 7) — either because you failed to enroll in a plan when you should’ve, or because you’re already in a plan but want to change to another for the following year. In either case, your coverage begins January 1.

But what if the time you’d normally sign up with a Part D plan happens to overlap the open enrollment period? For example, say your 65th birthday falls in December and you want drug coverage to begin December 1, along with your Part A and Part B coverage. You’d need to sign up with a plan during November — bang in the middle of open enrollment. The information you provide on the sign-up form should alert the plan to the fact that this time frame is your initial enrollment period, so your coverage should begin December 1, not January 1. But you may have to call the plan to make sure coverage will begin on the right day; open enrollment is an exceptionally busy time for the plans, and you don’t want your coverage delayed in the tumult.