Medicare Part B Late Enrollment Penalty: How It Works

Seniors Insurance Hub 2026-09-02

Opening answer

The Medicare Part B late enrollment penalty is an extra amount added to your monthly Part B premium if you go a full year (or more) after you are first eligible without signing up, and you do not qualify for a Special Enrollment Period.[1] It is not a one-time late fee. Medicare adds 10% of the standard Part B premium for each full 12-month period you could have had Part B but did not enroll, and in most cases you pay that add-on for as long as you have Part B.[1][3]

Most Greensboro and Piedmont families never owe it. You generally avoid the surcharge by signing up during your first seven-month Initial Enrollment Period, or by delaying Part B only while you (or your spouse) have group health coverage based on current work and then using the eight-month window after that job or coverage ends.[4][7]

How the penalty is added to your Part B premium

Part B is Medicare's medical insurance. It helps pay for doctor visits, outpatient care, and many preventive services, and it has a monthly premium even if you do not use those services in a given month.[5] For 2026, the standard Part B premium is $202.90 a month.[2] Some people also pay an income-related extra amount, which is separate from a late-enrollment surcharge.[2][5]

If you do not sign up when you are first eligible, and you do not qualify for a Special Enrollment Period, Medicare may raise your monthly premium by 10% for each full 12-month period you could have had Part B but did not take it.[1][3] The extra amount is added to every month's premium.[1][5] The percentage is counted in full 12-month blocks, so a delay of 11 months does not create a 10% add-on, while a delay of 24 months is two full years and a 20% add-on.[1][11]

Medicare's own 2026 example is the clearest picture of the math. If you waited two full years (24 months) to sign up for Part B and did not qualify for a Special Enrollment Period, you would pay a 20% late enrollment penalty on top of the $202.90 standard premium.[1] Twenty percent of $202.90 is $40.58.[1] Added together, that is $243.48, which Medicare rounds to the nearest $0.10, so the monthly Part B premium in the example is $243.50 for 2026.[1][11]

The dollar cost of a given percentage can change because it is a share of the current standard premium. CMS set the 2026 standard at $202.90, which is $17.90 (about 9.7%) higher than the $185.00 standard in 2025.[2][9] A 20% add-on on a higher base is a larger dollar amount than the same 20% was the year before.[1][2]

This Part B rule is different from the Part A late-enrollment rule. Most people get premium-free Part A. If you have to buy Part A and you sign up late, that penalty is temporary (you pay it for twice the number of years you delayed), not for as long as you have the coverage.[1]

The main exception: coverage from current work

The usual way people delay Part B without a penalty is the rule written for people who still have job-based insurance. If you (or your spouse) are still working and you have group health plan coverage based on that current employment, you can wait to enroll in Part B.[5][7] You may sign up any time you still have that coverage. After the job ends or the group coverage based on current work ends (whichever happens first), you have an eight-month Special Enrollment Period to sign up for Part B, and you usually do not pay a late enrollment penalty if you use that window.[3][4][7]

North Carolina's Seniors' Health Insurance Information Program (SHIIP) describes the same protection, and CMS confirms that months of group health plan coverage are left out of the late-enrollment count.[3][8]

A few practical notes from the families we meet around Greensboro:

"Current work" is the key phrase. Coverage has to be tied to a job that is still going, yours or your spouse's (or, if you have Medicare based on disability, sometimes a family member's job).[4][7]
Ask your benefits office how the plan coordinates with Medicare, especially if the employer has fewer than 20 employees. Medicare notes that a smaller employer's plan might not pay for services unless you have both Part A and Part B.[6]
Keep proof of the job-based coverage. When you enroll through this Special Enrollment Period, Social Security generally needs an extra form showing you had group coverage while you or your spouse were working.[3][6] CMS lists Form CMS-40B (to enroll in Part B if you already have Part A) and Form CMS-L564 (Request for Employment Information) for this path.[3]

This exception is why some people who are still working choose not to take Part B at 65. That can be a sound choice when the employer plan is paying first and you enroll later in the eight-month window.

Three enrollment windows that matter

You enroll in Part B during a defined window. Which one you use decides both when coverage starts and whether a penalty is on the table.

Your Initial Enrollment Period is a seven-month window. It starts three months before the month you turn 65, includes your birthday month, and ends three months after the month you turn 65.[4] If you already receive Social Security or Railroad Retirement benefits, Medicare may enroll you automatically. If you are not, you contact Social Security to sign up.[3][8] Coverage always starts on the first of a month, and the start date depends on which month of that seven-month window you use.[4] If you do not have qualifying job-based coverage, this is the cleanest way to start Part B on time.

After that first window ends, the job-based Special Enrollment Period is the path that keeps the penalty off the premium. It is available while you still have group health plan coverage based on current employment, and it continues for eight months after that employment or that coverage ends, whichever happens first.[4][7] Coverage generally starts the first month after you sign up.[4] If you want Part B to begin when the job-based plan ends, Medicare's guidance is to sign up the month before you or your spouse plan to retire.[6] If you sign up while you (or your spouse) are still working, or within the first full month after employer coverage ends, you can ask to delay the Part B start date up to three months.[4] This window does not apply if you are eligible for Medicare based on End-Stage Renal Disease, or if you are still in your Initial Enrollment Period.[4]

If you are not in either of those windows, the General Enrollment Period runs each year from January 1 through March 31. Coverage starts the first day of the month after you sign up.[3][4][8] This is the window where a penalty most often appears. SHIIP tells North Carolina residents that if you enroll here after missing your first chance, your monthly Part B premium may increase by a permanent 10% for each year of delayed enrollment, unless you are eligible for Special Enrollment.[8] A March 2026 audit by the Social Security Administration's Office of the Inspector General identified 101,516 Old-Age and Survivors Insurance beneficiaries who enrolled in Part B during the 2023 and/or 2024 General Enrollment Periods and whom SSA penalized for late enrollment.[10] That is not a forecast. It shows that many households land in this yearly fallback.

Coverage that does not pause the clock

Several kinds of health coverage feel like "I still have insurance," yet they do not count as group health plan coverage based on current employment.

COBRA does not extend the eight-month window. Medicare states that COBRA is not considered group health plan coverage for this purpose, and that getting COBRA does not change when the Special Enrollment Period ends.[4] Your eight-month clock to sign up for Part B starts when you stop working, even if you choose COBRA or other coverage that is not Medicare.[6] SHIIP gives North Carolina residents the same warning.[8]

Retiree coverage, VA coverage, and Marketplace coverage do not qualify either. SHIIP groups retiree health plans, VA coverage, and individual coverage (including Health Insurance Marketplace plans) with COBRA: none of them count as current-employment coverage for this window.[8] Medicare lists the end of COBRA or retiree coverage, a missed eight-month window, and having or losing Marketplace coverage as situations that do not qualify.[4] If you have VA coverage and you skip Part B when you are first eligible, you may still face a Part B late enrollment penalty.[6][8]

Those programs can still be useful coverage. They simply do not buy extra time on the Part B penalty clock. If a parent in Greensboro is leaving a job and taking COBRA, the date that matters is eight months after work (or the job-based plan) ended, not the day COBRA runs out.

How the premium, the add-on, and other Part B costs fit together

Keep three numbers separate. The standard premium is $202.90 a month in 2026 for people who do not pay an income-related extra amount.[2][5][9] The Center for Medicare Advocacy reports the same $202.90 standard and a $283 annual Part B deductible.[12] The late-enrollment add-on is the 10% per full 12-month period described above, usually paid for as long as you have Part B.[1][3][5] CMS reports that income-related monthly adjustment amounts affect roughly 8% of people with Medicare Part B; for 2026, individual filers with modified adjusted gross income above $109,000 (or joint filers above $218,000) pay a higher total premium, ranging from $284.10 up to $689.90 a month depending on income.[2] You can have a late-enrollment add-on without an income-related extra, or the reverse, or both. Medicare also says you generally will not have to pay a Part B penalty if you enroll in a Medicare Savings Program.[1]

After the $283 deductible, you usually pay 20% of the Medicare-approved amount for covered Part B services.[5] That is ordinary cost sharing, not the late-enrollment penalty. People who later add a Medicare Supplement (Medigap) policy or a Medicare Advantage plan still need Part B in place.

What Greensboro and Piedmont families can do

Our team hears these questions from adult children as often as from the person turning 65. The useful moves are calm and specific.

Name the coverage you have today. Is it from a current job (yours or a spouse's), a retiree plan, COBRA, VA, Medicaid, or a Marketplace plan? Only current-employment group coverage opens the eight-month Part B Special Enrollment Period described above.[4][7][8]

Put the dates on a calendar, and do not treat COBRA as extra Medicare time. Write down the last month of work, the last month of employer group coverage, and the eight months that follow. If you want Part B to start when the job-based plan stops, plan to file the month before that end date.[6] Use COBRA if it is the right medical coverage for a short gap, but enroll in Part B inside the eight-month window that started when work or the job-based plan ended.[4][6]

If you already delayed and you are not sure whether a penalty applies, ask Social Security how it counted your months. The same OIG audit found processing errors in a share of sampled cases, including months of group health plan coverage that were not credited.[10] Bring employment records so the uncovered-month count is complete.

Use North Carolina's free counseling line as a second opinion on the federal rules. SHIIP counselors are not licensed insurance agents and do not sell or endorse a product, plan, or company.[13] The statewide number is 1-855-408-1212, and local volunteer counselors are available by appointment in every North Carolina county.[8][13]

When you are ready to look at how Part B will sit next to a supplement, an Advantage plan, or other senior coverage, our services overview maps the products we help Piedmont families compare. We will help you match the window you are actually in.

Practical takeaways

The Medicare Part B late enrollment penalty is a 10% add-on to the standard premium for each full 12-month period you were eligible but did not enroll, and it usually lasts as long as you have Part B.[1][3]
In 2026 the standard Part B premium is $202.90 a month. Medicare's published two-year example is a 20% add-on of $40.58, rounded with the premium to $243.50 a month.[1][2]
You generally avoid the surcharge by enrolling in your seven-month Initial Enrollment Period, or by delaying Part B only while you have group coverage from current work and then using the eight-month Special Enrollment Period after that job or coverage ends.[4][7]
COBRA, retiree plans, VA coverage, and Marketplace plans do not count as current-employment coverage for that eight-month window.[4][8]
The yearly General Enrollment Period (January 1 through March 31) is the fallback. Coverage starts the following month, and a penalty may apply if you did not qualify for a Special Enrollment Period.[3][4]
Keep job-based coverage records, and call SHIIP at 1-855-408-1212 for free, unbiased counseling in every North Carolina county.[3][8][13]

How we can help

Have more questions or want to get in touch? Visit https://thesih.com/contact/ or call Seniors Insurance Hub at (336) 937-7501. We are an independent Medicare and senior insurance advisory serving Greensboro and the Piedmont. Bring the dates of work, employer coverage, and any COBRA or retiree paperwork you have. Our team will help you see which enrollment window you are in.

Citations

Medicare.gov, "Avoid late enrollment penalties" (2026)
Centers for Medicare & Medicaid Services, "2026 Medicare Parts A & B Premiums and Deductibles" (2025-11-14)
Centers for Medicare & Medicaid Services, "Original Medicare (Part A and B) Eligibility and Enrollment" (2026-03-10)
Medicare.gov, "When does Medicare coverage start?" (2026)
Medicare.gov, "What does Medicare cost?" (2026)
Medicare.gov, "When can I sign up for Medicare?" (2026)
Medicare.gov, "Special Enrollment Period (SEP)" (2026)
N.C. Department of Insurance, Seniors' Health Insurance Information Program (SHIIP), "The Road to Medicare: Planning Your Drive Toward 65" (revised 2024-10)
Federal Register / CMS, "Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026" (2025-11-19)
Social Security Administration Office of the Inspector General, "Medicare Part B Premium Penalties" (audit 072402, 2026-03-31)
Medicare.gov, "Sign up for Part B package (United States)" (2026 premium example)
Center for Medicare Advocacy, "2026 Medicare Parts A & B Premiums and Deductibles" (2025-11-20)
N.C. Department of Insurance, SHIIP, "Contact Seniors' Health Insurance Information Program (SHIIP)" (2026)