What Happens If I Miss My Medicare Enrollment?
October 22, 2025 | John Demko
Enrolling in Medicare at the right time, and on time, is essential to avoiding gaps in health insurance coverage; not only that, but enrolling late could lead to penalties and increased costs that build up over time.
Knowing exactly when to sign up can be confusing, especially without proper guidance or if you plan to work past 65. Do you have to sign up now if you plan to keep your employer-sponsored insurance coverage? These are all important considerations to know when to sign up for Medicare and avoid any lapse in coverage and affordable access to care.
If you've missed your initial enrollment window, here's what you need to know to get back on track.
Understanding Medicare Enrollment Periods
Let's start by covering the key Medicare enrollment periods so you can understand when you have the option to enroll in Medicare.
Initial Enrollment Period (IEP)
Your initial enrollment period, or IEP, is when you first become eligible for Medicare. For most individuals, this is when they turn 65 years old. The enrollment timeline for this period is a 7-month window which begins 3 months prior to your birth month, the month you were born and lasts 3 months after.
Special Enrollment Periods (SEPs)
A special enrollment period triggered by certain life events, such as job loss, moving, or losing coverage.
General Enrollment Period (GEP)
The general enrollment period is for individuals who missed their IEP or applicable SEP window. This period runs annually from January 1–March 31, if you enroll during this timeframe, your Medicare coverage will begin the month after you enroll.
Find Out More About Medicare Election Periods
Some individuals should enroll for Original Medicare Part A and B when they are first eligible. Others may only enroll in Part A initially if they are still working and have a creditable health plan through their employer.
Learn more about Medicare Enrollment and Working Past 65 in our Guidebook.
Consequences of Missing Medicare Enrollment
What happens if you miss your Medicare enrollment window? There are a couple of consequences you'll face that are best to avoid if you can.
Gaps in Coverage
Depending on your situation, you may end up with a lapse in health insurance coverage. If you need medical care, you may have limited access due to not having insurance, and out-of-pocket costs could leave you with a hefty bill.
Late Enrollment Penalties
The other consequence you'll face for not enrolling in Medicare when you were first eligible to do so is penalties. These penalties are tied to several parts of Medicare, and the amounts can vary, but in general, the longer you go without coverage, the higher they will be.
- Part A and Part B premiums
- Part D penalties for prescription drug coverage
Understanding Late Enrollment Penalties
Medicare Part A for most individuals does not have a premium; however, if you have not met the qualifications for this and you do not enroll right away, you may have a penalty. The penalty will increase your Part A monthly premium by 10% for twice the number of years you delayed enrollment.
Medicare Part B has a monthly premium, and if you do not sign up when you are first eligible, you will be subject to a penalty. Part B penalties are calculated by adding a 10% fee to your Part B premium for each full 12-month period you delay enrolling.
The most common Medicare penalty is a Part D penalty. Part D penalties occur when you do not sign up for Medicare Part D prescription drug coverage when you begin Medicare (even if you are not taking any medications). Part D penalties are calculated as 1% of the national average premium of a Part D plan per month you went without creditable coverage or a Part D plan. So if you went 2 years without a Medicare Part D plan, you will pay 24% of the national base premium.
Learn more about Medicare Penalties and How to Avoid Them
As you can see, over time these penalties can add up substantially, which is why it is imperative to understand your Medicare enrollment timelines and sign up at the right time.
Are there any exceptions that allow me to avoid late enrollment penalties if I missed my enrollment window?
There are some exceptions that allow you to avoid late enrollment penalties if you didn't sign up for Medicare right away. They vary, but some of the most common would be dual eligibility (Medicare and Medicaid), qualifying for extra help or low-income subsidies, and having creditable coverage through an employer or union. Additionally, if you obtain prescription coverage through VA benefits, you can avoid a Part D penalty.
How to Enroll After Missing Your Initial Window
If you missed signing up for Original Medicare when you were first eligible, you will have the opportunity to enroll during the General Enrollment Period (GEP). At that time, you will also be able to sign up for additional coverage, such as a Medicare Advantage plan (MA/MAPD), Medigap plan, or Medicare Part D plan.
You may also be able to sign up sooner if you have a qualifying special enrollment period.
If you signed up for original Medicare on time but missed signing up for additional coverage such as a Medicare Supplement or Medicare Advantage plan, there will be varying opportunities to sign up for these types of coverage. These include the Medicare Annual Enrollment Period (AEP), during a Special Enrollment Period (SEP) if eligible, and some Medicare Supplement plans (Medigap policies) allow for year-round enrollment; however, you may not be guaranteed acceptance.
Tips to Avoid Future Enrollment Issues
If you've missed your initial enrollment window for Medicare, determine now when you can enroll next. If you have questions about your timeline or when you're eligible to sign up, reach out to our team of Medicare professionals. We can help you put a plan in place to ensure you sign up at the right time.
Also note, once you sign up for Medicare, there are additional enrollment timeframes you'll want to stay on top of. The most significant is the Annual Enrollment Period (AEP) that occurs annually. This renewal window runs from October 15th - December 7th and allows you to make changes to your Medicare coverage for the following calendar year.
Want to make sure you don't miss out on an important deadline?
Sign up for our quarterly e-newsletter where we highlight important Medicare changes, news, events and more.
Staying on top of your Medicare enrollment, timelines, and deadlines is crucial to getting the coverage you need and avoiding penalties and higher costs. If you have or think you may have missed your enrollment into original Medicare or additional coverage, don't wait any longer, potentially letting penalties grow.
Reach out to our team today to find out your options and get personalized guidance.
Choosing a Medicare plan can be difficult. Twin City Underwriters helps Medicare recipients in Minnesota, Wisconsin, North Dakota, South Dakota, Iowa and Florida find the Medicare plan that meets their unique needs. Schedule a one-on-one meeting with one of our Medicare insurance brokers to get your questions answered!
Do you need help with Medicare, insurance and health plans? Explore your options with Allina Health Aetna, BlueCross BlueShield of Minnesota, Medica, UCare, United HealthCare and more. We work with you to find the best plan for your needs and budget. Contact us today to get started.