Medicare Part D: Prescription Drug Coverage

Original Medicare doesn’t cover most prescription drugs — that’s where a separate plan for prescription drug coverage (Part D) comes in.

Medicare Part D: Overview of Medicare Prescription Drug Coverage

Since 2006, Medicare Part D has helped beneficiaries cover the cost of prescription drugs, which are not insured through Original Medicare. Part D is offered via private companies as a stand-alone plan (PDP) for Original Medicare enrollees, or as a set of benefits included in a Medicare Advantage Plan. Each plan covers an extensive list of prescription drugs, called a formulary.  

Many plans organize the prescription drugs they cover, both brand name and generic, into “tiers” to help lower costs. Each tier costs a different amount, with those in the lower tiers generally costing less. Each plan establishes its own premiums annually, so there is no standard monthly premium for Part D coverage, so it's important to review your prescription costs each year. 

In most cases, even if you don’t currently take medications, enrolling in a plan could save you from paying a penalty for prescriptions later on.  If you don’t sign up for a Part D plan when you’re first eligible for Medicare you may have to pay a “late enrollment penalty”. This amount increases every month that you don’t have Part D and can get expensive quickly. The good news is that low-cost plans are available. If you have Medicare Part A and/or Part B and lack other drug coverage, the increasing costs of prescription drugs makes it advisable to enroll in a Part D plan as soon as possible.

Why Should I have Prescription Drug Coverage?

Prescription drug costs can add up quickly. Enrolling in a Part D plan helps relieve the financial burden of out-of-pocket prescription drug expenses. This is particularly true for those who need specialty prescriptions or require multiple brand-name medicines (you may also be charged a late penalty if you have no creditable drug coverage). 

Key Advantages of Medicare Part D

Choice of Plans

With many different Medicare Part D plans available, you can pick one that fits your budget and needs

Access to Preferred Pharmacies

Many plans have a network of preferred pharmacies where you can get your medication at a lower cost


These plans are designed to be flexible so you can change plans or make adjustments during Medicare enrollment periods as your needs change.

What do Medicare Part D plans cover?

All Part D plans must cover a wide range of prescription drugs, including those in certain “protected classes,” such as drugs that treat cancer or HIV/AIDS. Both brand-name and generic drugs are covered under Medicare Part D plans, though generics must include the same active ingredient as their brand-name versions and meet the same standards for quality, purity, and strength.

All Medicare drug plans must cover at least two drugs per drug category, though each plan can choose which Part D-covered drugs they’ll cover. While a plan’s formulary may not include an exact medication you need, a similar alternative option is available in most cases. You can request an exception if you or your prescriber believe that none of the drugs on your plan’s formulary will work for you.

Below is a sample of the kind of tier levels that prescription drug plans use to establish cost levels:

  • Tier 1: most generic prescription drugs, lowest co-payment
  • Tier 2: preferred brand-name prescription drugs, medium co-payment
  • Tier 3: non-preferred brand-name prescription drugs, high co-payment
  • Specialty drugs and biosimilars: high-cost prescription drugs, highest co-payment

What isn't covered by Medicare Part D plans?

Each Medicare Part D prescription drug plan decides which drugs not to include in its formulary, though most exclude prescription drugs for things like weight loss or gain, fertility, sexual dysfunction, hair growth and over-the-counter medications.

Prescription Drug Coverage & Medicare Advantage: What To Know

Medicare pays a fixed amount to companies that offer Medicare Advantage Plans. Medicare Advantage Drug Plans (MA-PDs), which help cover drugs as well as medical services, are generally utilized by people who receive Medicare benefits in a combined package via a PPO or HMO. A Medicare Advantage Plan may also provide coverage for things like basic vision, routine dental, and hearing services, as well as fitness-based activities*. 

*There may not be a plan in your area that has these benefits in one plan

Prescription Drug Coverage & Medigap: What To Know

Medigap policies purchased after 2006 do not include prescription drug coverage. If you have a Medigap plan that includes prescription coverage your insurer must remove that coverage if you enroll in a Part D plan. It’s important to bear in mind that most Medigap drug coverage is not considered creditable, so it may benefit you to join a Part D plan.  

Medicare drug coverage costs

Due to the inherent variability of drug coverage costs, SmartMatch is unable to provide specific costs. Numerous factors account for the variety of drug coverage costs, including:

  • Type of prescription
  • Whether or not it’s on your plan’s formulary
  • Which tier the drug falls under
  • Whether your deductible has been met, or if you’re in catastrophic coverage 
  • Whether your pharmacy is in or out of network

Drug coverage payments to expect

The cost of drug plans differ, as do the specific prescription drugs they cover. Checking a plan’s formulary will help you avoid selecting a plan that doesn’t cover the drugs you need.

You can expect to make the following payments for a Medicare drug plan (per

  • An annual deductible
  • Premiums
  • Coinsurance or copayments
  • Coverage gap costs
  • Costs for late enrollment

What influences drug coverage costs

Pharmaceutical companies take into consideration a drug’s effectiveness and uniqueness, as well as competition from other manufacturers when it comes to pricing. Research and development costs, which play a role in bringing new drugs to market, also factor into pricing.

Donut Hole: The prescription drug coverage gap

Most Medicare drug plans have a temporary limit on what the plan will cover commonly known as a “donut hole”. This limit may change from year to year; in 2023, once you’ve reached $4,660 you’re in the coverage gap aka the donut hole.

NOTE: The majority of people will not spend enough to enter the coverage gap.

How to compare Medicare drug coverage costs

A licensed insurance agent can help you comparison shop drug coverage plans and costs and identify the option that best fits your situation. SmartMatch Insurance Agency serves as a partner, analyzing a range of coverage options to help you find the one that most closely suits your needs. 

Medicare Part D: Enrolling and Changing Prescription Drug Coverage Plans

You can choose a Part D plan as soon as you become eligible to enroll in Part D coverage. Bear in mind that it’s best to enroll in a plan when you first become eligible. If not, you will most likely pay higher premiums later on. Medicare levies a 1% increase on premium costs for each month you delay enrollment, though there’s a 62-day grace period. Contact a SmartMatch licensed insurance agent for assistance in finding the best plan for you, or visit our Comparison Shopping tool to start the process.

If you wish to change drug coverage plans, you can do so during the Open Enrollment Period (Oct. 15 - Dec. 7), or during the Medicare Advantage Enrollment Period (Jan. 1 - March 31).

When to Enroll in a Prescription Drug Plan

Initial Enrollment Period

The Initial Enrollment Period (IEP) for Medicare Part D is usually the same as the IEP for Medicare Part B. The IEP for Medicare Part D is typically a seven-month window starting three months before you're eligible for Medicare (typically three months before your 65th birthday month). During this time you can sign up for a Medicare prescription drug plan.

Open Enrollment Period

You can join, switch, or drop a plan during the Open Enrollment, which runs from Oct. 15 - Dec. 7.  This is also referred to as the Annual Enrollment Period or the Annual Election Period. Your coverage will begin on Jan. 1 as long as your request is received by the Dec. 7 deadline. 

Medicare Advantage Open Enrollment Period

If you are enrolled in a Medicare Advantage Plan, you’re eligible to switch to a different Medicare Advantage Plan or enroll in a separate plan through Original Medicare from Jan. 1 - March 31 each year. Remember that you can only switch plans once during this three-month period. 

Special Enrollment Periods

Special Enrollment Periods (SEP) allow you to make changes to your prescription drug coverage when circumstances, such as loss of other coverage or relocation, occur.  

When to Change a Prescription Drug Plan

Open Enrollment Period

In most cases, you may only make changes to Medicare Part D prescription drug coverage during the fall Open Enrollment or Annual Enrollment Period (Oct. 15 - Dec. 7). You can change plans as many times as you need during Open Enrollment. It’s generally advisable to make as few changes as possible to avoid enrollment complications.

Medicare Advantage Open Enrollment Period

Part D coverage can be changed during Medicare Advantage Open Enrollment from Jan. 1 - March 31 annually. To do so, you must dis-enroll from your Medicare Advantage Plan and enroll in a different MA Plan with prescription drug coverage or Original Medicare with a stand-alone Part D plan. 

Special Enrollment Periods

You may be eligible to make changes to your Part D coverage during a Special Enrollment Period under certain circumstances, which may include:

  • Loss of creditable coverage through no fault of your own
  • Making a change to your job-based coverage
  • Moving out of your Part D plan service area
  • Dis-enrolling from a Medicare Advantage Plan and enrolling in Original Medicare as long as you joined the MA Plan upon becoming eligible for Medicare based on your age

Part D Late Enrollment Penalty: What To Know

A late enrollment penalty may be added to your Part D premium if, after your Initial Enrollment Period (IEP) is over, you go 63 or more consecutive days without Medicare or other creditable coverage. You will likely pay this penalty for as long as you have Medicare drug coverage. 

How much you’ll pay is determined by how long you went without Part D or other creditable prescription drug coverage. Your penalty amount is determined by multiplying 1% of the national base beneficiary premium by the amount of uncovered months you were without Part D or creditable coverage. The national base beneficiary premium in 2023 is $32.74, an amount that may change from year to year.  

Frequently Asked Questions About Medicare Part D: Prescription Drug Plans

The four prescription drug coverage stages are transitional phases during which your drug plan costs may change depending on which stage you are in. They include:

  • Annual deductible - Starts with your first prescription of the plan year. In this phase, you pay the full cost of your prescriptions until spending reaches the amount of your deductible.   
  • Initial coverage - During this phase, your plan covers a portion of your prescription drug purchases for medications covered under your plan’s formulary. You pay the rest in the form of a copayment or coinsurance (the amount depends on the drug’s tier level). 
  • Coverage gap - In the coverage gap, your plan is limited to how much it can pay for your medications. If you enter the gap, you pay 25% of the plan’s cost for covered brand-name drugs and 25% of the cost for generic drugs. You’ll pass out of the coverage gap once your out-of-pocket cost for covered medications reaches $7,400 (not including premiums).
  • Catastrophic coverage - You pass out of the coverage gap once you reach the $7,400 threshold. At this point, you transition into catastrophic coverage, which means you pay a low coinsurance or copayment amount for all covered prescription drugs. Your plan and the government cover the rest.

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