You enroll in Part D through Medicare or a private insurance company, during specific enrollment periods

Medicare Part D is prescription drug coverage you add to Original Medicare (Parts A and B) or to a Medicare Advantage plan. You do not get it automatically — you have to choose a plan and enroll. Most people enroll during their Initial Enrollment Period, which is the seven months that includes the month you turn 65. If you miss that window, you can still enroll during the General Enrollment Period (January 1 to March 31 each year), but you may pay a penalty for each month you were without coverage.

You can enroll through Medicare.gov, by phone at 1-800-MEDICARE, or by working with a licensed insurance agent. The process takes about 15 minutes online. You will need your Social Security number and information about your current medications and pharmacies, though you can complete enrollment without that information and update it later.

Key Takeaways

  • Your Initial Enrollment Period is the seven-month window that includes the month you turn 65; enrolling during this time avoids a lifetime penalty.
  • Part D plans vary widely in cost, deductibles, and which drugs they cover, so comparing plans before you choose matters even if you have used the same pharmacy for years.
  • You can enroll online at Medicare.gov, by phone, or with an insurance agent, and the process takes about 15 minutes.
  • If you have limited income, you may pay little or nothing for Part D through the Low-Income Subsidy program, which you can request when you enroll.
  • You can change your Part D plan once a year during the Annual Enrollment Period (October 15 to December 7), even if you are already enrolled.

When you can enroll in Part D

Your Initial Enrollment Period runs for seven months: three months before the month you turn 65, the month you turn 65, and three months after. If you enroll during this window, your coverage starts on the first day of the month you turn 65 or the first day of the following month, depending on when in the month you enroll. If you turn 65 in March, for example, your Initial Enrollment Period runs from December through June.

If you miss your Initial Enrollment Period, you can enroll during the General Enrollment Period from January 1 to March 31 each year. Coverage would start July 1 of that year. However, Medicare charges a penalty for each month you went without Part D coverage after your Initial Enrollment Period ended. The penalty is roughly 1% of the national average Part D premium per month, and it stays on your premium for as long as you have Part D. If you were without coverage for 24 months, for example, your penalty would be about 24% higher than the base premium.

You can also enroll if you have a may have access to life event — losing employer coverage, moving out of your plan's service area, or becoming may be able to access for Medicaid. You have 63 days from the event to enroll, and coverage starts the first of the month after you enroll.

How to enroll through Medicare.gov

Go to Medicare.gov and sign in with your username and password. If you do not have an account, you can create one with your email address and Social Security number. Once you are logged in, click "Prescription Drug Plans" and enter your zip code. Medicare will show you all Part D plans available in your area, ranked by estimated yearly cost.

You do not need to know your medications before you enroll. If you want to compare how much each plan will cost for your specific drugs, you can enter them into the plan comparison tool. Type the name of each medication, the strength (such as 10 mg), and how often you take it. The tool will show you the cost under each plan, including what you pay at the pharmacy and what Medicare pays. This step takes longer but helps you pick the plan that costs least for your actual prescriptions.

Once you have chosen a plan, click "Select Plan" and follow the prompts to complete enrollment. You will be asked to confirm your contact information and review the plan's details. After you submit, you will receive a confirmation number. Medicare will mail you a membership card within 7 to 10 days. Your coverage starts on the first of the next month or on January 1, whichever comes first, if you enroll by December 7.

Enrolling by phone or with an agent

You can call 1-800-MEDICARE (1-800-633-4227) to enroll over the phone. Have your Social Security number and Medicare number ready. The call usually takes 15 to 20 minutes. A Medicare representative will ask which plan you want and confirm your address and phone number. You will receive a confirmation number at the end of the call.

You can also work with a licensed insurance agent who represents Part D plans. Agents can help you compare plans, explain coverage details, and complete enrollment at no cost to you — the insurance company pays the agent's commission. To find an agent, search "Medicare insurance agent near me" or ask your doctor's office for a referral. Make sure the agent is licensed by your state's insurance department before you give them personal information.

Understanding Part D plan types and costs

Part D plans fall into two main types: Prescription Drug Plans (PDPs), which you add to Original Medicare, and Medicare Advantage Prescription Drug Plans (MA-PDs), which bundle medical coverage and drug coverage together. If you have Original Medicare and want drug coverage, you choose a PDP. If you switch to Medicare Advantage, drug coverage is included in that plan.

Every Part D plan has a deductible — the amount you pay out of pocket before the plan starts paying. In 2024, deductibles range from $0 to $545, depending on the plan. After you meet the deductible, you pay a copay (a fixed amount per prescription) or coinsurance (a percentage of the drug's cost). These amounts vary by plan and by drug tier — generic drugs usually cost less than brand-name drugs.

Part D plans also have a coverage gap, sometimes called the "donut hole." Once you and your plan have spent a combined $5,850 on covered drugs in 2024, you enter the gap and pay a higher percentage of drug costs until you reach $7,050 in out-of-pocket spending. After that, you pay a small copay for the rest of the year. The exact amounts change each year, so check your plan's details annually.

If you have limited income: the Low-Income Subsidy

If your income is below 150% of the federal poverty level, you may pay little or nothing for Part D through the Low-Income Subsidy (LIS) program. In 2024, that means a monthly income below roughly $1,550 for a single person or $2,100 for a married couple, though these amounts change yearly. The subsidy covers your deductible, copays, and coinsurance, and it protects you from the coverage gap.

You can request the Low-Income Subsidy when you enroll in Part D by checking the box on the enrollment form. Medicare will review your income and assets and tell you within two weeks whether you may have access to. If you do, your plan will be adjusted automatically, and you will pay the reduced amounts starting the month your coverage begins. You do not need to explore separately or contact Social Security.

If your income changes during the year, tell Medicare right away. You can update your information by calling 1-800-MEDICARE or by logging into your Medicare account online. If you become may be able to access for Medicaid, you automatically may have access to for the full Low-Income Subsidy.

Changing your plan or coverage

You can change your Part D plan once a year during the Annual Enrollment Period, which runs from October 15 to December 7. Any plan you choose during this period will start January 1 of the next year. You do not need a reason to change — you can switch to a different plan straightforward because you want to.

If you have a may have access to life event (such as losing employer coverage or moving), you can change your plan outside the Annual Enrollment Period. You have 63 days from the event to make the change. If you are already enrolled in a plan and your medications or costs change during the year, you can contact your plan to ask about coverage exceptions or to request that a non-covered drug be added to the plan's formulary (the list of covered drugs).

What to do if you have questions about your plan

Your Part D plan's customer service number is on your membership card. Call that number if you have questions about whether a specific drug is covered, what your copay will be, or whether you need prior authorization (approval from the plan before the pharmacy fills the prescription). Many plans also have online portals where you can check your deductible status, see what you have spent so far, and find in-network pharmacies.

If you think your plan made a mistake or denied coverage for a drug you believe should be covered, you have the right to appeal. Your plan will explain how to file an appeal in its materials, or you can call customer service and ask. Appeals usually take 30 to 60 days.

Frequently Asked Questions

What happens if I do not enroll in Part D when I turn 65?

You can still enroll later, but you will pay a penalty for each month you were without coverage. The penalty is roughly 1% of the national average Part D premium per month and stays on your premium permanently. If you go without coverage for two years, your penalty would be about 24% higher than the base premium for life.

Can I use my current pharmacy with any Part D plan?

Most Part D plans use large pharmacy networks that include chain pharmacies and many independent pharmacies. However, not all pharmacies are in-network for every plan. Before you enroll, check whether your current pharmacy is in-network for the plan you are considering. If it is not, you can ask the pharmacy to join the network or switch to a different plan.

Do I need to know my medications before I enroll?

No. You can enroll in a Part D plan without listing your medications. However, if you enter your medications into the plan comparison tool before you choose, you can see exactly how much each plan will cost for your prescriptions. This takes extra time but helps you pick the cheapest plan for your situation.

What if my doctor prescribes a drug that my Part D plan does not cover?

You can ask your plan for a coverage exception, which means asking them to cover a drug that is not on their formulary. Your doctor will need to submit a request explaining why that specific drug is medically necessary. The plan usually decides within 72 hours. If they say no, you can appeal or ask your doctor about a covered alternative.

Can I switch Part D plans if I am unhappy with mine?

Yes, during the Annual Enrollment Period (October 15 to December 7) you can switch to any other Part D plan available in your area. The new plan starts January 1. If you have a may have access to life event like moving or losing employer coverage, you can switch outside this window within 63 days of the event.