The Medicare Late Enrollment Penalty: Exactly What It Costs in 2026 — and How to Avoid It

Most explanations of the Medicare late enrollment penalty leave out the part that actually matters: it isn’t a one-time fee you pay once and forget. For Part B and Part D, it’s a permanent surcharge added to your monthly premium for as long as you have Medicare — usually the rest of your life. And because it’s recalculated each year against a base premium that tends to rise, the dollar amount can grow over time.

That’s what makes a “small” penalty expensive. A 20% Part B penalty doesn’t sound like much until you multiply it across 15 or 20 years of retirement. This guide gives you the exact 2026 formulas, real dollar examples, the lifetime cost, and — most importantly — the specific situations that let you avoid the penalty entirely or appeal one you’ve already been charged.

The one rule that makes these penalties painful

Three facts do most of the damage:

1. They’re permanent. For Part B and Part D, the surcharge stays on your premium for life. Switching plans doesn’t reset it.
2. They stack over time. The longer you wait, the bigger the percentage.
3. They can rise. Because the penalty is a percentage of a base premium that changes annually, your dollar penalty can increase even if you do nothing.

(The Part A penalty works differently and applies to very few people — more on that below.)

Part B late enrollment penalty (2026)

The formula: Your Part B premium goes up 10% for each full 12-month period you were eligible for Part B but didn’t enroll, unless you had qualifying coverage (like an employer plan) that let you delay. The standard Part B premium in 2026 is $202.90 per month.

Here’s what that looks like at different delays, using the 2026 base premium:

So someone who delayed Part B for 7 full years would pay roughly $344.93 per month in 2026 — the $202.90 base plus a $142.03 penalty — and would keep paying an inflated premium for life.

The lifetime math is the real story. Take a modest 2-year delay: about $487 a year. Over a 20-year retirement, that’s roughly $9,700+ — and more once you account for premium increases along the way. One important nuance: even if your income raises your Part B premium (IRMAA), the penalty is still calculated on the standard base premium, not your higher amount.

Part D late enrollment penalty (2026)

Part D — prescription drug coverage — has its own separate penalty, and the trigger is stricter than people expect: going 63 days or more without “creditable” drug coverage after your Initial Enrollment Period ends.

The formula: 1% of the national base beneficiary premium for each full month you went uncovered. In 2026, that base is $38.99 per month. The result is rounded to the nearest 10 cents and added to your Part D premium.

A worked example: Suppose you became eligible for Medicare but skipped Part D — with no other creditable drug coverage — for 30 months before finally enrolling. Your penalty is 30% of $38.99, which is about $11.70 per month, added to your Part D premium for as long as you have Part D. That’s roughly $140 a year, and since the base premium is recalculated annually, the amount can drift upward over time.

Note the trap here: this penalty applies even if you later pick a $0-premium Part D plan. The surcharge rides along on top of it.

Part A penalty — why most people can ignore it

Roughly 99% of people get premium-free Part A because they (or a spouse) paid Medicare taxes for at least 40 quarters. If that’s you, there is no Part A late penalty to worry about.

Only people who must buy Part A face this one. For them, the premium can run up to $565 per month in 2026, and the late penalty adds 10% for twice the number of years you delayed. Unlike Part B and D, this penalty is temporary — it ends after that period. If you get premium-free Part A, skip this section entirely.

Who is exempt — and how to avoid a penalty

You will not owe a penalty if you fit one of these:

• You had creditable coverage. For Part B, that usually means active employer coverage through your or your spouse’s current job. For Part D, it means drug coverage expected to pay at least as much as a standard Medicare drug plan (your plan is required to tell you each year whether it’s creditable — keep those letters).
• You get Extra Help (the Part D Low-Income Subsidy). If you qualify, the Part D penalty doesn’t apply to you at all.
• You use a Special Enrollment Period (SEP) correctly when your other coverage ends.

The SEP deadlines are where people get burned, so mark them:

• Part B: after your employer coverage ends, you have 8 months to enroll without a penalty.
• Part D: after losing creditable drug coverage, you have 63 days to get new coverage.

And if you’re enrolling for the first time, your Initial Enrollment Period is the 7-month window that starts 3 months before the month you turn 65 and ends 3 months after it. Enrolling then avoids every version of this penalty.

Already been charged? You can appeal

If you receive a penalty you believe is wrong — for example, you had creditable coverage but it wasn’t recorded, or you were given incorrect information by an employer or insurer — you can request a reconsideration. Your plan sends you the penalty notice with instructions and the official form. Medicare’s contractor typically decides within about 90 days, and if they agree the penalty was wrong, it’s removed or reduced (sometimes with a refund).

For free, unbiased help sorting out whether a penalty applies or is worth appealing, contact your State Health Insurance Assistance Program (SHIP) — the counseling is free and the counselors don’t sell plans.

The bottom line

• The Part B and Part D penalties are permanent and grow with the delay.
• Part B: +10% of $202.90 per year late, for life.
• Part D: +1% of $38.99 per uncovered month, for life.
• Most people avoid all of this simply by enrolling during their Initial Enrollment Period, or by keeping creditable coverage and using the SEP deadlines (8 months for Part B, 63 days for Part D) when that coverage ends.
• If you think you were penalized in error, request a reconsideration.

Sources

Figures in this guide reflect 2026 rates from official and independent sources, including Medicare.gov’s page on avoiding late enrollment penalties, Medicare Interactive, and the National Council on Aging (NCOA). Premium figures are 2026 standard amounts and change annually.

Written by Jinsoo Park, independent Medicare researcher & editor. Last updated July 6, 2026. This article is an independent guide and is not affiliated with the U.S. government or Medicare. Penalty amounts depend on your specific enrollment history and are ultimately determined by Medicare (CMS); premium figures change each year. Always confirm your situation at Medicare.gov or by calling 1-800-MEDICARE. This is general information, not medical, legal, or financial advice.