Medicare Late Enrollment Penalty: How to Avoid & Calculate It

Forfeiting Medicare's enrollment period results in permanent monthly premium increases for the rest of your life. The 2026 penalties apply to Part A (if you are not enrolled in premium-free Part A), Part B and Part D, with each having its own calculation and each continuing for eternity. The biggest is the Part B late enrollment fee: 10% paid to your monthly premium for every 12-month period that you could have been enrolled but were not. With a two-year delay, the standard Part B premium ($202.90) becomes $243.48 per month, with a cost of $9,740 in additional premiums over the course of a 20-year retirement. The Part D late enrollment penalty is an extra 1% per month of the national base beneficiary premium ($38.99 in 2026) added to the Part D premium and will always remain in effect. If you need to purchase Part A due to lack of 40 Medicare-taxed years of work history, then the Part A penalty (10% of the premium for twice the number of years missed) will apply.

This guide details each Medicare late enrollment penalty, the formula used to determine it, who it applies to and strategies that have been shown to avoid the penalties. Medicare.gov, CMS and the Centers for Medicare and Medicaid Services Special Enrollment guidance provide the information. 

The Part B late enrollment penalty: how it works

This is the largest of all Medicare penalties as Medicare Part B provides the most costly recurring services (doctor visits, outpatient services, durable medical equipment) and the penalty is permanent.

The penalty is 10% of the regular Part B premium for every full 12-month period in which you were eligible but didn't enroll. If you have no Special Enrollment Period and enroll in Part B two years later, you would be subject to the standard premium of $202.90 for Part B (20% penalty for each 12 months, or 10% for each year). That is an additional cost of $40.60 per month (rounded) as compared to $202.90 the standard.

The penalty continues throughout your period of having Part B, usually for life. The dollar amount will increase annually due to the annual increase in the standard premium, since the penalty is based on the standard premium from the current year. If the premiums continue to rise at the 20% rate, the penalty for 2026 would be $40.58 per month and would be about $48-$52 per month in 2030.

The late enrollment fee is added to beneficiaries' already higher monthly premiums with higher income, who also pay Income-Related Monthly Adjustment Amounts (IRMAA). IRMAA brackets begin at $109,000 income (or $218,000 for couples filing jointly) for 2026.

Penalty is applicable regardless of whether or not there was other cover during the delay period. The following types of coverage are NOT a factor in the late enrollment penalty for Part B coverage: COBRA coverage or retiree health plans or individual insurance policies. Employer group health plan coverage from your current employer (or your spouse's current employer) that has 20+ employees is the only plan that offers a Special Enrollment Period to avoid penalties.

See our working past 65 guide for information about working past 65 with employer cover. 

The Part D late enrollment penalty

If you don't have creditable prescription drug coverage for 63 or more days after you miss your IEP, the Part D late enrollment penalty will also apply. “Creditable coverage” refers to prescription drug coverage that provides coverage of at least equal to coverage under a standard Medicare Part D plan.

The 2026 penalty is 1% of the national base beneficiary premium ($38.99 in 2026) per month of no coverage, rounded to the nearest 10 cents and applied to your premium for a lifetime of coverage.

One example: If you don't have any creditable drug coverage for 24 months following eligibility, your penalty is 24% × $38.99 = $9.40 per month (rounded). This is added to your Part D premium for as long as you have Medicare drug coverage.

The amount of penalty will vary annually as it is a percentage of the national base premium, which varies from year-to-year. The percentage, however, does not change from this amount and was calculated at the time of enrollment.

Employer group health plans (check in writing), TRICARE for veterans, Department of Veterans Affairs prescription benefits, Federal Employees Health Benefits (FEHB), and union retiree plans are acceptable sources of coverage. Before relying on this status, you should always confirm this with a written statement from the creditors. Not all employer plans are ‘creditable’.

The most common exemptions from the Part D late enrollment penalty are Special Enrollment Periods (SEP), those who receive Medicare Extra Help (no Part D penalty for those with low incomes who are eligible for extra help), and individuals who had creditable coverage for the entire time they were eligible for Medicare.

See our Part D guide for more information on Medicare Part D coverage. 

The Part A late enrollment penalty

The Part A late enrollment penalty applies only to the 1% of Medicare beneficiaries who must buy Part A because they don't have 40 quarters of Medicare-taxed employment. For premium-free Part A beneficiaries (99% of enrollees), no penalty applies regardless of when they enroll.

For those buying Part A, the 2026 monthly premiums are $311 (with 30-39 quarters of work) or $565 (with fewer than 30 quarters). The late enrollment penalty adds 10% to your monthly premium for twice the number of years you went without enrolling.

For example, if you delayed Part A enrollment by 4 years and have 30-39 quarters of work, your penalty is 10% added for 8 years (twice the 4-year delay). At the 2026 premium of $311, you'd pay approximately $342 monthly for 8 years before the penalty drops off.

Unlike Part B and Part D penalties (which are permanent), the Part A penalty has a limited duration. After paying the penalty for twice the years you delayed, it ends.

For more on Part A, see our Part A coverage guide.

How to avoid late enrollment penalties

The cleanest way to avoid penalties is enrolling in Medicare during your Initial Enrollment Period (IEP). This is the seven-month period beginning three months before your 65th birthday month, including your birthday month, and extending three months after. For most beneficiaries, this means signing up between three months before turning 65 and three months after.

If you delayed Medicare enrollment because you have active employer coverage with a current employer (yours or your spouse's), you'll typically qualify for a Special Enrollment Period (SEP) when that coverage ends. The SEP gives you 8 months to enroll in Part A and/or Part B without facing late enrollment penalties.

For people working past 65 with employer coverage, several important rules apply. If your employer has 20+ employees, you can typically delay Part B without penalty, with employer coverage as primary and Medicare as secondary if you enroll in both. If your employer has fewer than 20 employees, Medicare becomes the primary payer, and you typically should enroll in Part B at 65 to avoid coverage gaps.

If you mistakenly miss your Initial Enrollment Period, you can enroll during the General Enrollment Period (January 1-March 31 each year), but coverage doesn't begin until July 1 and late enrollment penalties typically apply.

For details on enrollment periods, see our enrollment periods guide.

Special situations that avoid penalties

Several specific situations protect you from Medicare late enrollment penalties.

Medicare Extra Help recipients don't face Part D late enrollment penalties regardless of how long they go without prescription drug coverage. The 2026 Extra Help income limits are $23,940 single or $32,460 married couple.

Equitable relief is available in rare circumstances if you received incorrect official information from the Social Security Administration or Medicare that caused you to miss your enrollment window. The burden of proof is on you, and approvals are uncommon. Document everything if you're seeking equitable relief.

If your employer provided written verification that their coverage was creditable but it later proved not to be, you may have grounds for relief from Part D penalties. Save all correspondence about creditable coverage status.

Some state pharmaceutical assistance programs (SPAPs) and other assistance can help eligible low-income beneficiaries with Part D costs and may protect against some penalty implications. Contact your State Health Insurance Assistance Program (SHIP) for state-specific options.

The lifetime cost of late enrollment penalties

Understanding the lifetime cost of Medicare penalties can be a powerful motivator for timely enrollment.

A 2-year Part B delay at 2026 rates costs approximately $40.60 per month, or $487 per year. Over a 20-year retirement (age 65 to 85), that totals roughly $9,740 in extra premiums. Over 25 years (age 65 to 90), approximately $12,175.

A 5-year Part B delay costs $101.45 per month at 2026 rates, or $1,217 per year. Over 20 years, approximately $24,350 in extra premiums.

The Part D penalty is smaller per month but still significant over time. A 36-month delay creates a penalty of 36% × $38.99 = $14.00/month at 2026 rates. Over 20 years, approximately $3,360 in extra premiums.

Combined Part B and Part D late enrollment penalties for someone delaying both can easily exceed $30,000-$50,000 in additional premiums over a typical retirement period.

For most retirees, the lifetime cost of late enrollment penalties significantly exceeds the cost of working with a Medicare-licensed insurance broker or attorney to ensure proper enrollment timing.