Home › Knowledge › Medicare Part D
Vedanth Bhartee
Writer · Reviewed by Richard ChanUpdated Jun 12, 2026
3 min read
The Medicare Annual Enrollment Period (AEP), running from October 15 to December 7 each year, is the designated time for beneficiaries to switch, drop, or join a Part D prescription drug plan.
Medicare Part D plans update their formularies and tier pricing annually, meaning a medication covered fully one year might cost significantly more the next.
Beneficiaries can incur a lifetime late enrollment penalty if they go 63 or more consecutive days without creditable prescription drug coverage after their Initial Enrollment Period ends.
If you're enrolled in Medicare, reviewing your Medicare Part D drug plan during the Medicare Annual Enrollment Period isn't just a good idea — it's one of the most consequential financial decisions you can make each year.
Why does it matter so much? Here are just a few of the reasons why an annual review is worth your time:
The potential upside of this annual review is real and substantial. Some beneficiaries save as much as 200% to 300% after reviewing their drug coverage and switching to a plan that better covers their specific medications.
That kind of savings doesn't happen by accident — it happens because someone took the time to actually compare their current plan against what else is available. It's worth doing every single year.
Start by making a complete, current list of every prescription medication you take — including anything new you've started in the past twelve months.
You could then call individual insurance companies that offer competing Part D plans and ask them how each one covers your specific drugs. That approach works, but it's time-consuming and difficult to compare across plans in a structured way.
There is a better, faster, and more comprehensive way to conduct your review.
Simply enter the names of the prescription drugs you take into a plan comparison tool and see exactly how each available plan covers those medications.
You'll see how much each plan pays each month for the drugs on your list. You'll learn whether generic alternatives are now available that could lower your costs. And you'll be able to compare copayments across plans side by side — including how those costs shift throughout the year as you move through different coverage phases. (Remember: what you pay for prescriptions can change significantly from one month to the next depending on where you are in the coverage cycle.)
If lowering what you spend on medications is a priority — and for most Medicare beneficiaries, it should be — the path forward is clear.