Quick summary
Missing a Medicare enrollment deadline can add a surcharge to your premiums. For Part B and Part D, that surcharge generally lasts as long as you keep the coverage. The Part B penalty is 10% of the standard premium for each full 12-month period you could have enrolled but didn’t.
Many people reach 65 and assume Medicare will sort itself out. Some are still working. Some are covered by a spouse’s plan. Some figure they can sign up later and avoid a premium in the meantime. That last assumption is the one that causes the most trouble. Medicare charges late enrollment penalties that are added to monthly premiums, and in most cases the surcharge stays for as long as you have the coverage.
This article explains how those penalties work. It covers Parts A, B and D, how the Part B penalty adds up over time, and which steps insurers and consumer organizations say can help avoid it. The figures come from the sources listed at the end.
The Mistake: Delaying Enrollment Without Qualifying Coverage
The costly error is not signing up for Medicare when you are first eligible, and not having qualifying coverage to justify the delay. AARP notes that some people delay Part B because they have other coverage and want to avoid the monthly premium. If they don’t sign up when first eligible and don’t qualify for a special enrollment period, they may owe a late enrollment penalty.
The cost is not a one-time fee. It is added to the premium and, for Parts B and D, generally continues for as long as you keep that coverage. That is why the mistake keeps costing money every month, and so every year, of retirement.
How the Three Medicare Penalties Compare
Medicare has separate late enrollment penalties for each part that charges a premium. According to MedicareFAQ’s 2026 guide, they work as follows:
| Medicare part | How the penalty is calculated | How long it lasts | 2026 base figure cited |
|---|---|---|---|
| Part A | 10% of the Part A premium for each full 12-month period delayed | Twice the number of years delayed | $565/month (full premium) |
| Part B | 10% of the standard premium for each full 12-month period delayed | For life (as long as you have Part B) | $202.90/month |
| Part D | 1% of the national base beneficiary premium × number of uncovered months | For life (as long as you have Part D) | $38.99/month (base) |
Source: MedicareFAQ, “Medicare Late Enrollment Penalties: The Complete 2026 Guide.”
Part A needs a note. Most people don’t pay a Part A premium, so the Part A penalty applies only to those who do. UnitedHealthcare says the Part A penalty applies if you have to pay a premium, and that it is 10% and charged for twice the number of years you delayed enrollment.
How the Part B Penalty Adds Up
Part B is the penalty most often discussed, because it generally never ends. AARP explains that it adds 10% of the standard Part B premium for each 12-month period when you could have had Part B but didn’t. It lasts as long as you have Part B. Because Part B premiums usually rise each year, the penalty usually rises with them.
Both MedicareFAQ and Covered USA put the 2026 standard Part B premium at $202.90 per month. Covered USA gives an example: a two-year delay adds $40.58 per month, bringing the monthly premium to $243.48. Over 12 months, $40.58 per month comes to $486.96.
Monthly penalty by length of delay (2026 premium)
The Part D Penalty
Prescription drug coverage has its own rule. MedicareFAQ describes the Part D penalty as 1% of the national base beneficiary premium multiplied by the number of uncovered months. It cites a 2026 base premium of $38.99 per month and says the penalty lasts as long as you have Part D. The dollar amount changes as the base premium changes.
UnitedHealthcare also stresses the importance of proof of coverage. It advises getting written confirmation that you had creditable prescription drug coverage. It also says that if you qualify for a Special Enrollment Period, you should enroll in Part D within the first two months of it.
When Delaying Is Allowed
Not everyone who delays is penalized. AARP says you may be able to delay if you or your spouse is still working and you have health insurance through either employer. After you lose job-based coverage, you must sign up during a special enrollment period. That means either while you are still working or within eight months of losing your health insurance.
Employer coverage must also count. UnitedHealthcare lists making sure employer coverage is considered creditable for both Part B and Part D as a step in avoiding penalties. Aetna adds that life events such as a move or loss of other health coverage may qualify you for a Special Enrollment Period.
What Happens If You Miss the Window
People who miss both their initial and special enrollment periods have another option. Covered USA says they can enroll during the General Enrollment Period, which runs January 1 through March 31 each year. It adds that they will owe a late enrollment penalty for the months they went without coverage, and that the penalty will be permanent.
The penalty is difficult to remove once applied. MedicareFAQ says there is no way to remove the Part B penalty except in limited cases. One example is a successful appeal based on misinformation from a federal employee. MedicareFAQ’s FAQ also states that enrolling in a Medicare Advantage plan does not avoid the issue, because you must still have Part B.
One narrow exception is noted by UnitedHealthcare. If you are under 65 and disabled, the Part B penalty ends once you turn 65, because you get another Initial Enrollment Period based on age.
