Medicare charges a permanent surcharge to people who skip Part B when they were first able to have it. The rule is simple and the math adds up fast: an extra 10% on the monthly premium for each full 12 months a person could have had Part B but did not sign up. With Medicare open enrollment running October 15 through December 7, 2026, plenty of people are looking at their coverage choices right now.

Medicare spells out the penalty on its page about avoiding Medicare penalties. The wording is plain. A person pays “an extra 10% for each year” they could have signed up for Part B but did not. The charge is added to the standard Part B premium every month.

How the 10% adds up month after month

Only full 12-month periods count. A person who waited 11 months past the end of their Initial Enrollment Period, the first window to join, has no penalty on that stretch. A person who waited 12 full months owes 10%. Waiting 24 full months means 20%, and so on, one step at a time.

Medicare gives a 2026 example. The standard Part B premium this year is $202.90 a month. For someone who waited two full years, the 20% penalty comes to $40.58, which lifts the monthly premium to $243.50. Using the same $202.90 base, one full year of delay adds $20.29, three years adds $60.87, and five years adds $101.45 a month.

Who is likely to owe it, and who can avoid it?

The people most exposed are those who turned 65, kept working or kept a spouse’s job, and then let Part B slide without checking whether that coverage counted. Medicare tells people to sign up during their Initial Enrollment Period unless they have similar coverage, such as through an employer. The phrase that matters is “similar coverage.” A plan that does not qualify can leave a person with a penalty clock running without knowing it.

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So the question for anyone who has not enrolled in Part B is whether the months since turning 65 were covered by a qualifying employer plan or a window that waives the penalty. Anyone who finds a gap needs to know exactly how many full years it spans, because each one is another 10%.

Who can avoid the penalty?

Medicare says a person generally will not owe the Part B penalty if they qualify for a Special Enrollment Period or if they enroll in a Medicare Savings Program. A Special Enrollment Period is a window outside the usual dates that opens in certain situations, and it protects the person from the late charge. Medicare Savings Programs are state programs that help pay Part B costs for people with limited income.

Does the penalty ever go away?

For most people, no. Medicare says late enrollment penalties are usually charged for as long as a person has that type of coverage. A penalty set at 30% in the first year of Part B stays attached to the premium in later years, and it rises or falls only as the underlying standard premium changes. When Medicare sets a higher base premium, the same percentage produces a larger dollar amount.

That permanence is why the timing matters more than the size of any single year’s bill. A 10% surcharge looks small the first month. Across the rest of a retirement, on a fixed income, it becomes one of the larger recurring costs a person can create by missing a date.

Premiums can rise for other reasons too

The late penalty is not the only way Part B costs more. Medicare notes that a person may also pay a higher premium depending on their income. That is a separate add-on from the late charge, and the two can stack. Someone with a penalty and a higher income would see both reflected in the monthly amount.

People who already have Part B and want to know whether they carry a penalty can check the premium notice from Medicare or Social Security and compare it with the standard amount. If the number is higher than $202.90 and income is not the reason, a late penalty may be the cause, and the Medicare.gov page lists the avenues for asking about it.

What is still open for people who waited

For a person who has already waited, the penalty cannot be undone by signing up later, but the count stops growing on the day Part B starts. Every additional full year of delay is another 10% on top. The Medicare.gov page on avoiding penalties is the free place to see how Medicare counts the months and which situations waive the charge.

The open question for anyone with a gap is whether they qualify for a Special Enrollment Period or a Medicare Savings Program, because those are the two routes Medicare names for escaping the penalty. People on limited incomes have the most to gain from asking before the next premium notice arrives.

Facing a Part B penalty on a fixed income?

A late penalty of 10% for each full year is added to every Part B premium and stays for as long as the coverage does, so a missed enrollment window keeps costing money long after it passes. On a fixed income, a $40.58 monthly penalty on top of $202.90 is a real cut to the household budget.

The Medicare Cost & Coverage Protection Kit includes 51 state Medicare cost-help packs, one for every state and the District of Columbia, aimed at the programs that help pay Medicare premiums and cut drug bills. It also lays out the new Part D out-of-pocket cap and the steps to fight a denial.

Get the Medicare Cost & Coverage Protection Kit with your state’s cost-help pack →

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This article was produced with AI assistance and edited for accuracy against the sources linked above.