Not all Medicare Part D plans are the same. Plans may differ based on their networks of pharmacies, costs, or their formularies—the lists of covered prescription drugs. If you’re not happy with your plan, you may be able to switch, but only during certain times throughout the year. Read on to learn more about Medicare Part D enrollment periods and how to change your plan.

Know your Medicare Part D enrollment periods

If you are eligible for Medicare Part A and Part B (also called Original Medicare), you are also eligible for a Part D prescription drug plan. But you can only enroll during certain periods of the year. Your first opportunity is when you qualify for Medicare, or your Medicare Initial Enrollment Period (IEP). You can enroll in a Part D plan in the 3 months before you turn 65, the month of your 65th birthday or 3 months after. But there are other periods throughout the year where you may be able to change your Part D plan.

Open enrollment period

Your Medicare Annual Enrollment Period (AEP), sometimes called the Fall Open Enrollment Period, runs from Oct. 15 to Dec. 7 each year. During this time, you may make changes to your Part D plan or switch to a new one. Any changes you make will take effect on Jan. 1 of the next year.1

Medicare Advantage enrollment period

There is also a yearly enrollment period only for Medicare Advantage (MA) and Medicare Advantage prescription drug (MAPD) plan members, the Medicare Advantage Open Enrollment Period (MA OEP). This takes place from Jan. 1 to March 31 every year. You may switch, drop or make changes to your Part D plan during this time. Any changes you make will take effect the first day of the following month after your current plan processes your request.2

Special enrollment period

You could also drop, switch or make changes to a Medicare Part D plan after certain life events. This opportunity to change plans is called a Special Enrollment Period (SEP). Some life events that qualify for an SEP include changing where you live, losing your current coverage or your current plan changes its contract with Medicare.3

Explore Medicare prescription drug plans from Humana

Most Humana Medicare Part D plans come with added services, at no extra cost, to help you maintain your health and your budget. Compare available plans in your area today!

Compare Medicare Part D plans

Since Medicare Part D prescription drug plans may differ, it’s a good idea to shop for the right plan that suits your needs. offers a simple Part D plan comparison tool to help you find the plan that works for you.

Consider Medicare Advantage including prescription drug coverage

Many Medicare Advantage plans (Part C) include Part D prescription drug coverage. If you are already enrolled in Medicare Part A and Part B, you may qualify for Medicare Advantage.4

Some Medicare Advantage plans may offer other benefits beyond Original Medicare. See Humana’s Medicare Advantage plans to find one that may work for you and see if you’re eligible to enroll.

What you’ll need to change Medicare Part D plans online

If you are within the eligible enrollment periods for Medicare Part D, you can enroll in a new prescription drug plan online. You won’t need to cancel your old plan since your old coverage will stop once your new Medicare drug plan begins. Your new plan should send you a letter telling when your new drug coverage starts. Make sure you switch plans as soon as you can within your enrollment period. This may help ensure that you get your membership card for your new plan by the time your new coverage begins.5

Find the right Medicare Part D plan for your prescription needs

One Medicare Part D plan may be different from the next. The pharmacy networks,  list of covered drugs and costs can vary. Before you enroll in Medicare Part D or Medicare Advantage, compare plans and search for nearby pharmacies to find choose the prescription drug coverage that meets your needs.

Humana answers your Medicare questions


  1. Christian Worstell, “Medicare AEP vs. OEP: Know Your Enrollment Periods,”, last accessed August 9, 2023,
  2. “Medicare AEP vs. OEP: Know Your Enrollment Periods.”
  3. “Special circumstances (Special Enrollment Periods),”, last accessed August 9, 2023,
  4. “How to get prescription drug coverage,”, last accessed August 9, 2023,
  5. “How to switch your Medicare drug plan,”, last accessed August 9, 2023,

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