Medicare Late Enrollment Penalties: What They Are and How to Avoid Them

The short version: If you don't sign up for Medicare when you're first eligible — and you don't have other qualifying coverage — you can face penalties that get added to your premiums and, in most cases, stay there for the rest of your life. The good news: these penalties are almost entirely avoidable once you understand the rules. This page walks through each one in plain English.

Late enrollment penalties are one of the most common — and most expensive — Medicare mistakes I see. People assume Medicare is automatic, or that they can just sign up whenever they get around to it. For some parts of Medicare, waiting too long means paying more every single month, permanently. Let's make sure that doesn't happen to you.

The three penalties, at a glance

There are three separate late enrollment penalties, one for each part of Medicare that has one:

• Part A penalty — only affects the small number of people who have to buy Part A (most people get it premium-free).
• Part B penalty — the big one. Affects most people who delay without qualifying coverage.
• Part D penalty — the sneaky one. Affects people who skip drug coverage, even if they don't take medications.

Each works a little differently, so let's take them one at a time.

The Part B late enrollment penalty

This is the penalty that catches the most people, and it's the most expensive over time.

How it works: If you don't enroll in Part B when you're first eligible, and you don't qualify for a Special Enrollment Period, your monthly premium goes up by 10% for every full 12-month period you could have had Part B but didn't. And this penalty lasts for as long as you have Part B — for most people, that means for life.

A few important details:

• Only complete 12-month periods count. If you delayed for 14 months, that counts as one full period (10%), not two. Partial years don't round up.
• The penalty is calculated on the standard Part B premium ($202.90 in 2026), and it's recalculated each year as the premium changes — so the dollar amount grows over time.
• If you pay a higher income-related premium (IRMAA), the penalty is applied to the standard premium first; IRMAA is added separately.

What it actually costs: Say you delayed Part B for two full years without qualifying coverage. That's a 20% penalty. On the 2026 standard premium of $202.90, that's an extra $40.58 per month — about $487 per year, added to your premium for as long as you have Part B. Delay for seven years, and you're looking at a 70% penalty — roughly $142 more per month, pushing your premium to about $344.93. That's the trap: a decision to “wait and see” for a few years can cost you thousands over your retirement.

The Part D late enrollment penalty

This is the one people overlook most often, because they think, “I don't take many medications, so why would I need drug coverage?” That reasoning is exactly how the penalty catches people.

How it works: If you go 63 days or more in a row without Part D or other creditable prescription drug coverage after your Initial Enrollment Period, you may owe a penalty. It's calculated as 1% of the national base beneficiary premium ($38.99 in 2026) for each full month you went without coverage. That amount is rounded to the nearest $0.10 and added to your monthly Part D premium — for as long as you have Medicare drug coverage.

A few important details:

• The penalty is always calculated on the national base beneficiary premium, not on your specific plan's premium. So even if you later pick a $0-premium plan, you still owe the penalty on top of it.
• The base premium changes each year, so your penalty amount can change year to year.
• The penalty follows you even if you switch plans.

What it actually costs: Say you waited 24 months without creditable drug coverage. That's a 24% penalty. On the 2026 base premium of $38.99, that works out to about $9.40 per month added to your drug plan premium — for as long as you have Part D. It may not sound like much month to month, but it's permanent, it grows, and it was entirely avoidable.

How to avoid it — and this is the key insight: Even if you take few or no medications now, enrolling in a low-cost Part D plan when you're first eligible protects you from ever owing this penalty. Think of it as cheap insurance against a lifetime surcharge.

One thing to watch: If you have drug coverage through an employer, union, the VA, or TRICARE, that coverage may be “creditable” — meaning it counts and protects you from the penalty. Your plan is required to send you an annual notice telling you whether your coverage is creditable. Keep those notices — you may need them to prove you had coverage and avoid a penalty later.

The Part A late enrollment penalty

This one affects the fewest people, because most people get Part A premium-free — if you or your spouse worked and paid Medicare taxes for at least 40 quarters (about 10 years), you don't pay a Part A premium at all, and this penalty doesn't apply to you.

If you do have to buy Part A (because you don't have enough work history for premium-free coverage), and you delay enrolling, your Part A premium goes up by 10%. Unlike the other penalties, the Part A penalty lasts for twice the number of years you delayed — not for life. So if you waited two years, you'd pay the higher premium for four years.

In 2026, the Part A premium is $565/month (or $311/month for those with 30–39 quarters of work history), so a 10% penalty adds meaningfully to that. Because most people don't pay for Part A at all, this penalty is the least common — but if it applies to you, it's worth knowing.

Who's protected — and who gets caught

The theme running through all three penalties is the same: Medicare wants you to sign up when you're first eligible, unless you have other coverage that counts. The people who get caught are usually the ones who assumed something that wasn't true. The most common traps:

Assuming Medicare is automatic. It's automatic only if you're already receiving Social Security benefits before you turn 65. Otherwise, you have to sign yourself up.

Relying on COBRA. This is one of the most costly misunderstandings. COBRA coverage generally does not extend the Medicare Part B Special Enrollment Period, which is available based on current-employment group health plan coverage — not COBRA. If you're leaving a job and going onto COBRA, confirm your enrollment requirements before relying on it, because your Medicare enrollment clock may still be running. (COBRA may separately count as creditable drug coverage for Part D purposes — but that does not shield you from Part B penalties.)

Skipping Part D because you don't take medications. As covered above — this is exactly how the Part D penalty catches people.

Missing the enrollment window entirely. Your Initial Enrollment Period is the 7-month window around your 65th birthday. Miss it without qualifying coverage, and you may have to wait for the General Enrollment Period (January 1 – March 31) to sign up — and owe a penalty on top.

Who doesn't pay the penalty

Some people are protected from these penalties entirely:

• If you (or your spouse) have coverage through current employment, you can delay Part B without penalty and get a Special Enrollment Period when that coverage ends.
• If you have creditable drug coverage (from an employer, union, the VA, or TRICARE), you're protected from the Part D penalty as long as there's no gap of 63+ days.
• If you qualify for Extra Help (the Low-Income Subsidy) or Medicaid, the Part D late enrollment penalty is waived.

The bottom line

Late enrollment penalties are permanent, they grow over time, and they're almost entirely avoidable. The two things that protect you are simple:

1. Sign up during your Initial Enrollment Period unless you have qualifying coverage based on current employment.
2. Don't go 63+ days without creditable drug coverage — even a low-cost Part D plan protects you.

The tricky part isn't the rules themselves — it's knowing which ones apply to your situation, especially if you're working past 65, on COBRA, or juggling other coverage. That's exactly the kind of thing worth talking through before you make a decision you can't undo.

If you're not sure where you stand with your enrollment timing, that's one of the most valuable things to clarify — because these penalties are so much easier to avoid than to fix.

Figures on this page reflect 2026 Medicare amounts and change annually — always confirm current numbers at the official sources below.