If you think you missed a Medicare deadline, take a breath: most penalties are avoidable, and many people who worry about one never actually owe it. The Medicare late enrollment penalty is a surcharge added to your premium when you sign up for Part A, Part B, or Part D later than you were supposed to, without other coverage that counts. The amount depends on which part you delayed and for how long. This guide walks through how each penalty is calculated, how long it lasts, and the clear steps you can take to avoid one or keep it from growing. If you are still unsure which deadline applied to you, our guide to Medicare enrollment periods lays out every window.
How the penalty works, part by part
A late penalty is not a one-time fee or a bill for back premiums. For Part B and Part D, it is a permanent surcharge added to your monthly premium for as long as you keep that coverage. Each part calculates it in its own way, so it helps to take them one at a time.
Part B: 10% per year you delayed
If you do not enroll in Part B during your Initial Enrollment Period and you do not have other coverage that counts, your monthly Part B premium goes up 10% for each full 12-month period you could have had Part B but did not. The penalty stays with you for as long as you have Part B.
It is easier to see with a number. The standard Part B premium in 2026 is $202.90 a month. If you went two full years without Part B when you could have had it, that is a 20% surcharge, or about $40.58 added to that base premium, every month, for the rest of the time you have Part B. A single full year would be 10%; three full years, 30%. Partial years do not count, so a gap of 11 months adds nothing, while a gap of 13 months counts as one full 12-month period.
The most common way people avoid this is simple: sign up during your Initial Enrollment Period, the seven-month window around your 65th birthday. The other way is to have coverage from a current employer that lets you delay. If you are still working at 65, read our guide to creditable coverage before you decide to wait on Part B, because not every kind of insurance protects you.
Part D: 1% per month without drug coverage
Part D, the prescription drug benefit, has its own penalty, and it is keyed to months rather than years. For each full month you were eligible for Part D but went without it or without other creditable drug coverage, Medicare adds 1% of the national base beneficiary premium to your Part D premium. Like the Part B penalty, it lasts as long as you have Part D.
Two details matter here. First, the trigger is the 63-day rule: the penalty applies if you go 63 or more continuous days after the end of your Part D Initial Enrollment Period without either Part D coverage or other creditable drug coverage. A short gap will not cost you; a gap that crosses 63 days will. Second, the penalty is a percentage, not a fixed dollar amount. The "national base beneficiary premium" it is calculated from is a figure Medicare sets each year, so the exact dollar amount can shift slightly from year to year even though your percentage stays fixed. Your percentage is set by how many full months you went uncovered. For more on how this part works, see our Medicare Part D guide.
Part A: only if you have to buy it
Most people never face a Part A penalty, because about 99% of beneficiaries get Part A premium-free, based on at least 40 quarters (10 years) of Medicare-covered work. If you qualify for premium-free Part A, there is no late penalty to worry about, and you can sign up at any time.
The penalty applies only to the small share of people who must buy Part A because they do not have enough work history. For them, signing up late adds a 10% premium penalty, and unlike the others, you pay it for a set stretch rather than for life: twice the number of years you delayed. Delay two years, and you pay the higher premium for four.
| Part | How it's calculated | How long it lasts | How to avoid it |
|---|---|---|---|
| Part B | 10% added to your premium for each full 12-month period you could have had Part B but did not | As long as you have Part B | Enroll during your Initial Enrollment Period, or keep coverage from a current employer that counts |
| Part D | 1% of the national base beneficiary premium for each full month without Part D or creditable drug coverage | As long as you have Part D | Avoid a gap of 63 or more days; keep creditable drug coverage and your annual notice |
| Part A | 10% added to your premium, applies only if you must buy Part A | For twice the number of years you delayed | Sign up on time; most people get Part A premium-free and owe no penalty |
How to avoid a penalty
The good news running through all three penalties is that they are avoidable, and the steps are within your control. There are really two paths.
Enroll on time. The cleanest way to never owe a penalty is to sign up during your Initial Enrollment Period, the seven-month window that spans the three months before your 65th birthday, the month itself, and the three months after. If you are not sure your window has passed or is still open, our Medicare enrollment periods guide walks through each one.
Or keep coverage that counts, and keep the proof. If you have other coverage when you turn 65, you may be able to delay penalty-free, but only if that coverage is creditable. For drug coverage, creditable means it is expected to pay, on average, at least as much as Medicare's standard Part D coverage. Employer or union plans, retiree coverage, COBRA when it is creditable, TRICARE, VA drug benefits, and qualified State Pharmaceutical Assistance Programs can all count. Your plan must tell you each year whether your coverage is creditable, in a written Notice of Creditable Coverage that usually arrives before October 15.
Save those notices. If you later join a Part D plan, it may send you a letter asking about your prior coverage, and you will need to respond by the deadline to prove you had continuous creditable coverage and avoid the penalty. Keeping each year's notice in one place is the single best insurance against a Part D penalty you do not actually owe.
Frequently asked questions
For as long as you have Part B, which for most people means for life. The penalty is 10% added to your premium for each full 12-month period you could have had Part B but did not, and it does not go away once you finally enroll. That is why signing up during your Initial Enrollment Period, or keeping coverage that lets you delay, matters so much.
It can, but only if the coverage counts as creditable. Coverage from a current employer can let you delay Part B penalty-free, and drug coverage that pays on average at least as much as standard Part D lets you delay Part D penalty-free. Not every plan qualifies, and COBRA and retiree coverage are treated differently, so confirm your coverage is creditable before you decide to wait. See our creditable coverage guide for the details.
Each year, your plan sponsor sends a written Notice of Creditable Coverage, usually before October 15, telling you whether your drug coverage counts. Save these notices. When you later join a Part D plan, it may send a letter asking about your prior coverage, and you must respond by the deadline with proof of continuous creditable coverage to avoid the penalty. The annual notices are how you show you never crossed the 63-day gap.
Sometimes. If you believe a penalty was charged in error, for example because you actually had creditable coverage during the months in question, you can ask Medicare to reconsider, and your saved Notice of Creditable Coverage is the evidence that supports your case. People who qualify for help paying for drug coverage may also not be charged the Part D penalty. Because these situations turn on your specific records, it is worth gathering your notices before you start.
No. Signing up during a later window, like the General Enrollment Period, gets you enrolled, but it does not undo a penalty for the months you went without coverage you could have had. The penalty attaches when you enroll. That is why the goal is to avoid the gap in the first place, not to count on a later window to fix it.
Learn More
- What is Medicare? Parts A, B, C, and D explained
- When to sign up: Medicare enrollment periods
- Creditable coverage: how to delay Medicare without a penalty
- Medicare Part D drug coverage explained
If you are weighing whether to delay Medicare or worried you already missed a deadline, get personalized help sorting out your penalty risk and your next step at brevy.com.
The information on Brevy.com is for educational purposes only and is not a substitute for professional legal, financial, or medical advice. Rules vary by state and program and change frequently. Always verify with the relevant agency or a qualified professional. Brevy is not a law firm, financial advisor, or healthcare provider.