Medicare Part D was introduced because Original Medicare doesn’t cover prescription drugs. You can get Part D prescription drug coverage either through a standalone Part D plan or through a Medicare Advantage plan that includes Part D.
It’s important to understand how much plans differ. In 2026, there are 360 standalone plans, each with different premiums, deductibles, and copays—and each covers a different set of medications. One plan may also have varying costs depending on which pharmacy you get your prescription filled.
This guide looks at Medicare Part D prescription drug plans. We’ll show you what they cover, who should enroll, and how to choose the right plan. If you need a free personalized consultation, Chapter’s licensed Medicare Advisors will help you compare plans from every insurance carrier to find one that best fits your specific needs.
Key takeaways
Medicare Part D prescription drug plans help cover the cost of prescriptions, but plans vary widely. A plan with the cheapest premiums may still cost you more overall if it doesn’t cover your medications.
Even if you don’t take any medications today, you should consider enrolling in low-cost Part D coverage to avoid late enrollment penalties later.
Plans change, so review your plan during the Annual Enrollment Period to confirm you still have the best option.
What is Medicare Part D?
Medicare Part D is prescription drug coverage. Parts A and B (often called Original Medicare) cover inpatient and outpatient treatment. Part D covers some of the cost of prescriptions and is offered by private insurance companies approved by Medicare.
You can get Medicare drug coverage in two ways:
A standalone Part D plan
A Medicare Advantage plan that includes Part D coverage
56.1 million Americans have enrolled in Medicare Part D as of 2026. Of those, 24.9 million are enrolled in a standalone prescription drug plan, and 31.3 million are on a Medicare Advantage plan that includes Part D coverage.
Many people are worried about rising prescription drug prices. A plan that helps lower your share of drug costs is important, especially for people who rely on regular prescriptions.
Even if you don’t take prescriptions right now, it’s usually still worth getting low-cost Medicare Part D coverage to avoid late enrollment penalties later.
What do Medicare Part D prescription drug plans cover?
All Medicare Part D plans must cover a range of common medications, but specific coverage varies. Each plan has a “formulary” that lists covered medications, including at least two drugs in the most commonly prescribed categories and classes.
Plans have different cost tiers, with generic or preferred drugs costing less than non-preferred brand name drugs. Here’s an example:
Tier 1: Generic drugs, lowest copayment
Tier 2: Preferred brand-name drugs, medium copayment
Tier 3: Non-preferred brand-name drugs, higher copayment
Tier 4: Specialty tier for expensive medications, highest copayment
Part D coverage sometimes covers medications only for particular uses. For example, most plans cover weight loss drugs, like Ozempic, for diabetes treatment. These drugs may not be covered for general weight loss. Coverage depends on how the drug is prescribed and whether the plan lists it for that condition.
If your prescription isn’t on a formulary or is only covered under a high tier, you can discuss alternatives with your doctor or request an exception with your insurance carrier. If the plan provider approves the request, you’ll receive coverage or pay a lower tier cost.
Who should enroll in a Medicare Part D plan?
Most people with Medicare should consider Part D coverage because even if you don’t need any prescriptions right now, your healthcare needs can change. Part D is especially important if you’re:
Taking regular medication: If you’re among the 60% of Americans over 65 who take four or more prescription medications, the right Medicare Part D plan can significantly reduce costs.
New to Medicare: You first become eligible for Medicare when you turn 65. The Initial Enrollment Period is the best time for most people to choose Part D coverage.
Without “creditable coverage”: If you go 63 consecutive days without prescription drug coverage at least as good as Medicare, you’ll incur the Medicare Part D late enrollment penalty. So even if you don’t take any medications, consider enrolling to avoid penalties in the future and to have insurance in the event you do need a medication
Adding Medicare Part D isn’t necessary for everyone. Some people already have strong prescription drug coverage through other programs, including:
An employer or union retiree plan
VA benefits
TRICARE
If you have one of these options, you may not need a Part D plan. Compare the cost and coverage, and only switch if the new plan offers a clear advantage.
When can you enroll in a Medicare Part D plan?
You can only join a plan or change your coverage during specific Medicare Part D enrollment windows. Here are the options:
Medicare Initial Enrollment Period: This seven-month window opens three months before your 65th birthday month and closes three months after it. When you enroll in Part A or B, you can add a Part D plan.
Medicare Annual Enrollment Period: Every year from October 15 to December 7, you can join or leave a Part D plan, or switch to a different plan. Because plans can change annually, this is an ideal time to review your Part D coverage and make sure your plan still meets your needs.
Medicare Advantage Open Enrollment Period: This window only applies if you have a Medicare Advantage plan on January 1. From January 1 to March 31, you can switch to a different Medicare Advantage plan. You can also drop Medicare Advantage and go back to Original Medicare. If you go back to Original Medicare, you may enroll in a standalone Part D plan.
Special Enrollment Period: Special Enrollment Periods allow you to make changes outside of these standard enrollment periods. Qualifying events include moving, losing your current coverage, and changes in eligibility for benefits like Extra Help. Check Medicare’s full list of reasons for SEPs.
How do you choose the right Medicare Part D prescription drug plan?
The right Part D plan depends on your prescriptions and pharmacy preferences. Follow this process to compare plans:
List your medications: Create a complete list of drugs you take, including exact names and dosages. This includes drugs you may need occasionally through the year.
Check plan formularies: Compare your list against each plan’s formulary. See if the medications are covered, which tier they’re on, and any restrictions.
Check other plan details: Look at what your prescriptions will cost at the pharmacy you go to. Plans can have preferred pharmacies that offer lower prices. If you’re considering Medicare Advantage plans that have Part D coverage, check plan details outside of prescription coverage.
Estimate your total annual costs: Add up the costs you can expect to pay for your prescriptions over the course of the year. Make sure to consider deductibles, coinsurance, and copays. Add this amount to plan premiums for your total estimated cost.
Keep in mind that the plan with the lowest premiums may not have the lowest overall cost. That’s because a higher deductible or copayments for the medications you need can make a cheaper plan more expensive over the year. Balance cost against factors like coverage, drug availability, and pharmacy networks. Doing all of this for each of the Part D coverage options available to you can be challenging. If you talk to a Chapter Medicare Advisor, we can compare your options against your healthcare needs in minutes, saving you the time and the stress.
We recommend reviewing your plan every year during the Annual Enrollment Period. Plans can change their coverage details, new plans may become available, and your prescriptions can change. An annual review can help you save money or get better coverage by switching to a different plan.
Get help comparing Medicare Part D plans
Although the overall process of enrolling in Medicare Part D prescription drug plans is quite straightforward, the comparison process can feel overwhelming. There are many different plans, each with their own formularies, tiers, preferred pharmacies, and costs.
Need help comparing plans or understanding your options? Give us a call to get free advice from a licensed Medicare Advisor who can help you choose the best Medicare coverage for your specific needs. We can also see if you qualify for valuable benefits like Extra Help.
Call us today at 855-900-2427 or book an appointment to find the right Part D plan for your needs.
Sources
Kaiser Family Foundation (2025). A Current Snapshot of the Medicare Part D Prescription Drug Benefit. https://www.kff.org/medicare/a-current-snapshot-of-the-medicare-part-d-prescription-drug-benefit/
Kaiser Family Foundation (2026). Analyzing Changes in Medicare Part D Enrollment for 2026. https://www.kff.org/medicare/analyzing-changes-in-medicare-part-d-enrollment-for-2026/
Kaiser Family Foundation (2026). Public Opinion on Prescription Drugs and Their Prices. https://www.kff.org/health-costs/public-opinion-on-prescription-drugs-and-their-prices/
Medicare.gov (2026). How do drug plans work? https://www.medicare.gov/health-drug-plans/part-d/what-drug-plans-cover/how-drug-plans-work
Medicare.gov (2026). Joining a plan. https://www.medicare.gov/basics/get-started-with-medicare/get-more-coverage/joining-a-plan
Medicare.gov (2026). What pharmacies can I use? https://www.medicare.gov/health-drug-plans/part-d/what-drug-plans-cover/pharmacies
