The Basic Rule: If You Have Medicare, You Can Enroll in Part D

Medicare Part D is prescription drug coverage available to anyone who has Medicare Part A or Part B. You do not need to have both parts — either one is enough. If you are already receiving Medicare, you can enroll in a Part D plan. If you are not yet on Medicare but will be soon, you can enroll in Part D at the same time you sign up for your other Medicare coverage.

Part D is run by private insurance companies, not by Medicare directly. Each company offers different plans with different drugs covered and different costs. You choose which plan to join, and you can change plans once a year during the open enrollment period in the fall.

Key Takeaways

  • You must have Medicare Part A or Part B to enroll in Part D; having either one is sufficient.
  • Part D is optional — you do not have to take it, but waiting to enroll can result in a permanent penalty on your premiums.
  • You can enroll in Part D when you first become may be able to access for Medicare, during the annual open enrollment period, or if you have a may have access to life event.
  • If you have low income, you may be able to get help paying Part D premiums and out-of-pocket costs through the Low-Income Subsidy program.
  • People with employer or union retiree drug coverage should check whether that coverage is at least as good as Part D before declining Part D enrollment.

When You First Become may be able to access for Part D

You become may be able to access for Part D the month you turn 65 and enroll in Medicare Part A or Part B. You also become may be able to access if you are under 65 and already receiving Social Security Disability Insurance (SSDI) or have end-stage renal disease (ESRD) or ALS (amyotrophic lateral sclerosis).

When you first become may be able to access, you have a seven-month window to enroll in Part D without penalty. This window starts three months before the month you turn 65 (or the month you become may be able to access for Medicare for another reason) and ends three months after. For example, if you turn 65 in June, your enrollment window runs from March through September. If you enroll during this window, your coverage can start as early as the first day of the month you turn 65.

If you miss this window and do not have other drug coverage, you will pay a late enrollment penalty. The penalty is calculated as 1% of the national average Part D premium for each month you were not enrolled. Once you pay this penalty, it stays on your premiums for as long as you have Part D coverage.

Exceptions: When You Can Enroll Outside the Initial Window

Even if you miss your initial seven-month window, you can still enroll in Part D without penalty if you have what Medicare calls a may have access to life event. These include losing employer or union retiree drug coverage, moving out of your plan's service area, or having a change in your income that makes you newly may be able to access for the Low-Income Subsidy.

You also can enroll during the annual open enrollment period, which runs from October 15 through December 7 each year. Coverage from a plan you choose during this period starts on January 1. However, if you enroll during the open enrollment period and you missed your initial window, you will still owe the late enrollment penalty — the open enrollment period does not waive it.

People with Other Drug Coverage

If you have drug coverage through a current or former employer, a union, TRICARE (military coverage), the Veterans Administration, or a state Medicaid program, you may not need Part D. Before you turn down Part D enrollment, check whether your current coverage is at least as good as Part D. This is called creditable coverage.

Your employer, union, or other coverage provider should tell you in writing each year whether your coverage is creditable. If you are not sure, ask them directly. If your coverage is creditable, you can decline Part D without penalty. If you later lose that coverage, you will have a two-month window to enroll in Part D without penalty.

If your coverage is not creditable and you decline Part D, you will owe the late enrollment penalty when you eventually join, even if you were covered by something else in the meantime.

Low-Income Help with Part D Costs

If your income is below a certain level, you may be able to get help paying Part D premiums and out-of-pocket costs through the Low-Income Subsidy (LIS) program, also called "Extra Help." The income limits change each year. In 2024, you may be may be able to access if your monthly income is below about $1,550 for an individual or $2,100 for a married couple living together, though these figures vary by state and change annually.

You can explore for the Low-Income Subsidy through Social Security, by phone at 1-800-772-1213, or online at ssa.gov. You can also explore through your state Medicaid office. If you are approved, you will pay little or nothing for your Part D premiums, and your out-of-pocket costs for drugs will be capped at a much lower amount than they would be without the subsidy.

Part D and Other Medicare Coverage

Having Part D does not affect whether you can have Medicare Part A, Part B, or Part C (Medicare Advantage). Part D is separate from all of these. If you have a Medicare Advantage plan (Part C), that plan may include drug coverage, and you usually cannot also enroll in a standalone Part D plan. However, if your Medicare Advantage plan does not include drug coverage, you can enroll in Part D.

If you have Original Medicare (Part A and Part B), you can enroll in any standalone Part D plan. You can also enroll in a Medicare Advantage plan that includes drug coverage, but if you do, you must drop your standalone Part D plan.

What to Ask Your Doctor and Pharmacist

Before you choose a Part D plan, talk to your doctor and pharmacist about the drugs you take. Ask them which Part D plans cover your current medications and whether there are any restrictions — such as requiring you to try a cheaper drug first or limiting how much you can get at once. Your pharmacist can often tell you which plans in your area have the best prices for your specific drugs.

If you are already enrolled in a Part D plan and your doctor prescribes a new drug that is not covered, ask whether there is a covered alternative. If there is not, your doctor can request an exception from your plan, and the plan must respond within 72 hours.

Frequently Asked Questions

Do I have to enroll in Part D when I turn 65?

No, Part D is optional. However, if you do not enroll when you first become may be able to access and you do not have other creditable drug coverage, you will owe a late enrollment penalty for as long as you have Part D. The penalty is permanent and does not go away.

What happens if I miss my initial enrollment window?

You can still enroll during the annual open enrollment period (October 15 to December 7), but you will owe the late enrollment penalty. You can also enroll without penalty if you have a may have access to life event, such as losing employer coverage or moving out of your plan's service area.

Can I have Part D if I am still working and have employer drug coverage?

Yes, but check first whether your employer coverage is creditable. If it is, you can decline Part D without penalty. If it is not creditable, you should enroll in Part D to avoid the late enrollment penalty later.

How do I know if I may have access to for help paying Part D costs?

You can explore for the Low-Income Subsidy through Social Security at 1-800-772-1213 or ssa.gov. Income limits vary by state and change each year. If you are approved, you will pay much less for premiums and drugs.

Can I change Part D plans after I enroll?

Yes, you can change plans once a year during the open enrollment period (October 15 to December 7). If you have a may have access to life event, you may be able to change plans outside this window. Your new coverage will start on January 1 if you enroll by December 7.