You open a letter from your drug plan and see a line you did not expect: a “late enrollment penalty” added to your monthly premium. The charge is small at first, but it does not go away on its own, and it can follow you from plan to plan. Before you pay it for years, check whether it is correct. This guide explains how Medicare figures the Part D penalty, what counts as “creditable” drug coverage, and how to ask for a review if the penalty is wrong.
Every figure below comes from Medicare.gov, a CMS fact sheet, or the official reconsideration request form. Where a detail depends on your own plan or paperwork, I say so instead of guessing.
The rule in plain language
The penalty applies when your Initial Enrollment Period for Part D ends and you then go 63 or more days in a row without Medicare drug coverage or other creditable prescription drug coverage. If that happens and you sign up later, Medicare adds a penalty to your monthly Part D premium.
According to Medicare.gov, the penalty is worked out like this:
- Count the number of full, uncovered months you were eligible for Part D but had neither a Part D plan nor creditable coverage.
- Multiply that number by 1%.
- Multiply the result by the national base beneficiary premium. That benchmark is $38.99 for 2026, and CMS announced on July 28, 2026 that it will be $41.33 for 2027.
- Round to the nearest $0.10. The result is added to your monthly premium.
Medicare’s own example is a person with 14 uncovered months, who pays a 14% penalty. Because the base premium changes each year, the dollar amount can change even when your count of months does not.
What the penalty looks like in 2027
The table applies the formula above to the 2027 base premium of $41.33. I did the arithmetic myself and rounded each result to the nearest $0.10, as Medicare does. Your plan’s letter is the final word on your own amount.
| Full months without coverage | Penalty percentage | Added to monthly premium (2027) | Added over 12 months |
|---|---|---|---|
| 3 | 3% | $1.20 | $14.40 |
| 6 | 6% | $2.50 | $30.00 |
| 12 | 12% | $5.00 | $60.00 |
| 14 | 14% | $5.80 | $69.60 |
| 24 | 24% | $9.90 | $118.80 |
| 36 | 36% | $14.90 | $178.80 |
| 60 | 60% | $24.80 | $297.60 |
A worked example
Assume you turned 65, kept working, and had no drug coverage at all for 24 full months after your Initial Enrollment Period ended. Then you joined a Part D plan.
| Step | Calculation | Result |
|---|---|---|
| 1. Penalty percentage | 24 months x 1% | 24% |
| 2. Apply to the 2027 base premium | 24% x $41.33 | $9.9192 |
| 3. Round to the nearest $0.10 | $9.9192 rounds to | $9.90 a month |
| 4. Yearly cost | $9.90 x 12 | $118.80 |
That is on top of whatever your chosen plan charges. Because Medicare says you generally keep paying the penalty as long as you have Part D coverage, even if you switch plans, ten years of this penalty adds up to roughly $1,188 at today’s figures. The amount can also move as the base premium changes, so treat that total as an illustration, not a forecast.
What counts as “creditable” drug coverage
Coverage is creditable when it is expected to pay, on average, at least as much as Medicare’s standard drug coverage. If you had it, the months you were covered do not count against you. Medicare.gov’s page does not spell out the test, so I am relying on the official reconsideration form, which lists the kinds of proof Medicare’s reviewer accepts:
| Where your old coverage came from | Evidence the form asks for |
|---|---|
| Employer or union plan | A Notice of Creditable Prescription Drug Coverage, or a Certificate of Prior Creditable Prescription Drug Coverage, from that plan |
| Department of Veterans Affairs (VA) | Any one of: a Notice of Creditable Prescription Drug Coverage, a copy of your VA Health Benefit Card, a letter from the VA certifying eligibility, or an Explanation of Benefits |
| Indian Health Service, a Tribe or Tribal organization, or an Urban Indian Organization | An IHS registration card, or a letter verifying eligibility or enrollment |
| A prior Medicare Part D plan | No separate proof is needed; the form says there is no need to write a letter in this case |
If you are not sure your old coverage was creditable, the form suggests writing to the former plan and asking. Attach your letter and any answer. You should not wait for the reply before you file.
Which situation are you in?
- You had drug coverage through a job, a union, the VA, or the Indian Health Service the whole time. Gather the notice or card listed above. If your coverage was creditable and continuous, you should not have a penalty for those months.
- You had drug coverage but never got a clear notice about whether it was creditable. The form has a separate box for this. Most non-Medicare plans with drug coverage must send a notice comparing their coverage to Medicare’s, and plans may put it in a benefits handbook or send a separate notice.
- You had no drug coverage and simply waited. The penalty is probably correct. Check the month count, since errors in the count are the most practical thing to catch.
- You lived outside the United States during the period. The form includes a box for people who were not eligible to enroll in a Part D plan during the period your plan used. You must submit proof, such as proof of overseas residency.
- A serious medical emergency stopped you from enrolling. There is a box for this too. You need proof, for example records of an unexpected hospitalization.
- You get, or got, Extra Help. Medicare.gov says that if you get Extra Help you do not pay the late enrollment penalty. The form asks for the dates you had Extra Help.
How to dispute the penalty
If you disagree with the penalty, the path is a reconsideration request. Here is what the official form says:
- Find the date on your penalty letter. You have 60 days from the date on that letter to complete, sign, and mail or fax the form to the address or number printed on it.
- Use one form per person. A spouse who also has a penalty needs a separate form.
- Sign it. The form states that the enrollee’s signature is required to process the appeal.
- Check every box that fits your situation and fill in the dates and names of your earlier coverage.
- Attach your proof from the table above. Keep a copy of everything you send.
- If more than 60 days have passed, explain the reason for the delay on a separate sheet and send it with the form.
The form names C2C Innovative Solutions, Inc. as the independent contractor that Medicare uses to review these requests. By signing, you allow other organizations to release information the reviewer needs.
A simple timeline
| When | What happens | What to do |
|---|---|---|
| Around your 65th birthday | Your Initial Enrollment Period for Medicare and Part D runs | Join a Part D plan, or confirm in writing that your employer or union drug coverage is creditable |
| After that period ends | A gap of 63 or more days in a row without creditable coverage starts the penalty clock | Keep notices of creditable coverage; do not throw them away |
| When you later enroll | Your plan sends a letter stating the penalty | Note the letter’s date immediately |
| Within 60 days of that letter | Your window for a reconsideration request | Mail or fax the signed form with proof |
| Each January | The base premium changes, so the dollar penalty can change | Re-check the amount on your plan’s annual notice |
Common mistakes to avoid
- Counting calendar months loosely. The penalty counts full months, so ask the plan how it reached the number it used.
- Waiting for a reply from your old plan before filing. The form says not to wait.
- Missing the 60-day mark. If you are late, the form tells you to explain the reason for the delay on a separate sheet, so file on time if you can.
- Sending one form for two people. Each enrollee needs a separate, signed form.
- Assuming any old coverage counts. Only creditable coverage is excluded from the count, so get the notice that says so.
- Forgetting Extra Help. If you qualify, you do not pay the penalty at all.
Frequently asked questions
Does the penalty ever end?
Medicare.gov says you generally pay the penalty as long as you have Medicare drug coverage, including if you change plans. The way to remove it is through a successful reconsideration or by qualifying for Extra Help.
Is the base premium my actual premium?
No. The national base beneficiary premium is a benchmark used to calculate the penalty and plan payments. Your plan’s own premium is separate, and the penalty is added to it.
Why did my penalty change this year even though nothing about my history changed?
Your number of uncovered months stays the same, but the penalty is a percentage of the base premium, and that benchmark moves each year. CMS set it at $41.33 for 2027, up from $38.99 in 2026.
I had coverage through a former employer but never got a notice. What do I do?
Check the box on the reconsideration form for people who had drug coverage but did not get a clear notice, and write to the former plan asking whether it was creditable. Attach the letter and any answer.
Where do I find the official details?
Start with Medicare.gov’s page on the Part D late enrollment penalty, the button above. Your plan’s penalty letter explains how it counted your months and how to file.
This article is general information, not personal insurance or legal advice. For help reading a penalty letter, Medicare’s helpline and your State Health Insurance Assistance Program counselors are free resources.