Part D

Prescription coverage, priced by your own drug list.

Two plans with similar premiums can differ by a wide margin once your actual prescriptions are entered. Here is how Part D is built and what to check before you pick one.

A person checking health information while walking outdoors

Review your drug plan every fallFormularies, tiers, and pharmacy networks change at the plan year boundary. The Annual Enrollment Period from October 15 through December 7 is when you can switch, and the new plan starts January 1.

Two ways to get it

Standalone, or bundled into an Advantage plan.

Which route you take follows from the bigger Medicare decision you have already made.

01Standalone

A Part D plan next to Original Medicare

If you stay on Original Medicare, with or without a Medigap policy, you buy prescription coverage as its own plan. It is often called a PDP, and it has its own premium, drug list, and pharmacy network.

See standalone drug plans

02Built in

Drug coverage inside an Advantage plan

Most Medicare Advantage plans include Part D. Those are called MA-PD plans, and joining one means your medical and drug coverage come from the same insurer and the same card.

How Advantage works

03Formulary

Every plan covers a different list

A plan drug list, or formulary, puts covered drugs into tiers that determine your share of the cost. A drug can also require prior authorization, step therapy, or a quantity limit.

Check your drugs by ZIP

04Pharmacies

Where you fill matters

Plans have pharmacy networks, and many have preferred pharmacies where the same prescription costs less. Mail order can change the price again for maintenance medications.

Compare plans near me

See how the two Medicare paths compare

What you pay

Premium, deductible, copays, and a yearly ceiling.

You may pay a monthly plan premium, and depending on the plan, a yearly deductible before the plan starts paying its share.
After any deductible, you pay a copay or a percentage for each prescription, based on the tier the drug sits on in that plan formulary.
Federal law now sets an annual cap on what you pay out of pocket for covered Part D drugs. Once you reach it, covered prescriptions cost you nothing for the rest of the calendar year. The cap amount is set by the government and adjusted each year.
Medicare also offers a payment option that spreads your out-of-pocket drug costs across monthly payments over the plan year rather than paying them all at the pharmacy counter.
Extra Help, also called the Part D Low-Income Subsidy, lowers or eliminates premiums, deductibles, and copays for people whose income and resources qualify.
People with higher incomes pay an income-related monthly adjustment amount on top of the plan premium, based on their tax return from two years earlier.

The annual check

Six steps that take about twenty minutes.

The plan that was cheapest for you last year is frequently not the cheapest this year, because plans move drugs between tiers and change which pharmacies are preferred. Running this check each fall is the single most reliable way to avoid an unwelcome January.

Compare drug plans in my area See the enrollment windows

Read the Annual Notice of Change your plan mails in the fall. It lists next year premium, deductible, tier changes, and any drugs being removed.
List every prescription you take, with the dose and quantity, before you compare anything.
Check each drug against the plan formulary for the coming year, not the current year.
Confirm your pharmacy is still in network, and check whether it is a preferred pharmacy for that plan.
Compare the full year cost, premium plus deductible plus copays, rather than the premium alone.
Make any change between October 15 and December 7 so it takes effect January 1.

Dates and rules

Part D in four numbers.

Annual Enrollment Period, new plan starts January 1: Oct 15 to Dec 7
without creditable coverage can trigger the late penalty: 63 days
the late enrollment penalty stays on your premium: For life
on out-of-pocket costs for covered Part D drugs: Yearly cap

Good to know

Questions people ask about Part D.

Do I have to enroll in Part D?

It is voluntary, but delaying it has a lasting cost. If you go 63 days or more in a row after your Initial Enrollment Period without Part D or other creditable drug coverage, Medicare adds a late enrollment penalty to your premium, and that penalty stays with you for as long as you have Part D coverage. Creditable coverage means drug coverage expected to pay at least as much as standard Part D, such as many employer or union plans.

What if my drug is not on the plan list?

You can ask the plan for an exception, with your prescriber supporting the request, or ask whether a covered alternative would work. Plans have to follow a defined appeals process with deadlines, and there is a faster track when waiting would seriously harm your health.

Can I have a standalone Part D plan with a Medicare Advantage plan?

Generally no. If your Advantage plan includes drug coverage and you enroll in a separate Part D plan, you can be disenrolled from the Advantage plan and returned to Original Medicare. The main exceptions are certain plan types that do not offer drug coverage at all, such as Medical Savings Account plans and some Private Fee-for-Service plans.

When can I change drug plans?

During the Annual Enrollment Period from October 15 through December 7, with the new plan starting January 1. If you are in a Medicare Advantage plan, the January 1 through March 31 Advantage Open Enrollment Period also lets you make one change. Special Enrollment Periods can open after events such as moving, losing other creditable coverage, or qualifying for Extra Help.

Does Part D cover the drugs I get at the doctor office?

Often not. Drugs administered in a clinical setting, such as many infusions and injections given by a provider, are usually covered under Part B rather than Part D. Vaccines and self-administered prescriptions are typically the Part D side. If a specific medication matters to your budget, ask which part covers it before you choose a plan.

Part D

Compare drug plans against your own prescription list.

Enter your ZIP code to see the Part D plans offered in your area and what they cover.