Key takeaways:
Don’t wait to enroll in original Medicare or Medicare Advantage — and, if needed, standalone Part D prescription coverage or a Medigap supplement plan. Delays can force you to pay higher premiums.
Review the benefits offered by different Medicare plans and choose coverage that fits your health needs.
If you aren’t happy with your Medicare coverage, you will have at least one open enrollment period every year to make changes.
If you switch from Medicare Advantage to original Medicare and want to buy a Medigap supplement plan, you may be subject to medical underwriting. That means you could be accepted, approved with a higher premium, or denied coverage.
Enrolling in Medicare requires interpreting complex rules and observing important deadlines. Making a mistake while choosing or changing coverage can happen easily. Here are some common missteps you can avoid if you plan ahead and stay informed.
1. Assuming you’ll be automatically enrolled
Most people in the U.S. become eligible for Medicare around the time they turn 65. But you will not be automatically enrolled in original Medicare (Part A and/or Part B) when you turn 65 unless you are already receiving Social Security or Railroad Retirement Board benefits.
You may not necessarily want to enroll in Medicare when you turn 65 if you have another option for healthcare coverage. If you have coverage through your employer and continue to work after age 65, you can delay signing up for Medicare until you leave the workforce. (Or you can coordinate benefits between Medicare and your employer-provided insurance.) It’s just important to have adequate coverage during that time, or there may be enrollment penalties when you join Medicare.
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Whatever timing you choose, you’ll likely need to actively enroll in Medicare. To do this, you’ll need to be aware of enrollment deadlines.
If you are turning 65 and don’t have qualifying coverage from an employer, you’ll need to sign up for Medicare within your 7-month initial enrollment period to avoid penalties. Your initial enrollment period includes the 3 months before you turn 65, your birth month, and the 3 months that follow. Unless you have job-based insurance at a company with at least 20 employees, this initial enrollment period is the time to sign up.
You’ll need to apply for Medicare online, in person, or by phone. Once you’ve applied, make sure you receive your “Welcome to Medicare” package. If you wait too long to enroll, you will face lifelong penalties. These will be added to your premiums for Medicare Part A hospital insurance (if you don’t get premium-free coverage), Medicare Part B medical insurance, and Part D prescription coverage. We’ll talk more about late enrollment penalties later.
2. Not understanding your coverage options
Before you sign up for a Medicare, here are some questions you’ll need to consider:
Do you have preferred healthcare professionals that you’ll want in your coverage network? Almost every non-pediatric physician nationwide accepts Medicare. But Medicare Advantage plans typically cover specific healthcare professionals and facilities in a set area.
Are the services covered under original Medicare adequate for you? Or do you have health concerns that would be better addressed with a Medicare Advantage plan. Medicare Advantage plans often include certain vision, dental, and hearing benefits.
Would you prefer to sign up for Medicare Advantage during your initial enrollment period, given you’ll have a window to switch to original Medicare penalty-free? If you choose Medicare Advantage, you’ll have a 12-month period to see if you like your private coverage. Within that year, you can switch to original Medicare without penalty. If you then want to buy a Medigap supplement plan, you can do so without medical underwriting. It’s important to note that you can’t have Medigap coverage if you’re enrolled in Medicare Advantage.
Do you take any medications on a regular basis, or expect to take any in the future, that you’ll need coverage for? If so, you’ll want to enroll in a Medicare Part D plan at the same time that you join Part B — or choose a Medicare Advantage plan with adequate prescription coverage.
Do you plan to travel internationally, or expect to have a lot of out-of-pocket costs? If so, you may want to choose original Medicare paired with a Medigap policy, which will help cover your out-of-pocket costs and pay for some medical care abroad.
How much are you willing to pay for your coverage? Most people don’t pay a premium for Part A. You will have to pay a Part B premium whether you enroll in original Medicare or Medicare Advantage. Some Medicare Advantage plans also charge an additional premium for coverage — but most include Part D.
Are you comfortable with the limitations that come with Medicare Advantage coverage? While Medicare Advantage plans tend to offer more benefits, they come with certain limitations — such as tighter healthcare professional networks. Medicare Advantage plans also widely deploy prior authorization requirements, which can delay or prevent needed care. Though, original Medicare is testing wider use of coverage reviews with a 6-year pilot program involving six states.
How do you feel about the pros and cons of the different coverage options? Choosing original Medicare may give you the widest access to care, but you’ll have separate monthly premiums if you want Part D and/or Medigap. With an all-inclusive Medicare Advantage plan, you’ll have Part D coverage and extra benefits rolled in. But you may have more limited access to your preferred healthcare professionals and recommended care.
3. Neglecting to enroll in a Part D plan when you first become eligible
If you’re not taking any prescription medications when you first become eligible for Medicare, you may be tempted to delay enrolling in a Part D plan. Unfortunately, not signing up for a prescription plan when you first join Medicare can result in permanent late enrollment penalties added to your premiums if — or, more likely, when — you enroll later.
With age, you’ll probably need to take at least one prescription medication on a regular basis. A federal agency analysis of health surveys found that nearly half of older adults took five or more prescription medications. That’s why enrolling in an affordable Part D plan as soon as possible is often a good choice. While paying those monthly premiums may seem unnecessary now, it can save you money on penalties in the long run.
4. Not enrolling in the right Part D plan
If you’re already taking multiple medications, you’ll want a Part D plan with a formulary that includes them. Every plan’s formulary is different, so be sure to thoroughly review and compare your prescription coverage options.
You’ll also want to check that your preferred pharmacies are in your chosen plan’s network before you enroll. And you’ll want to find out if there are coverage restrictions, such as prior authorization requirements or quantity limits, you’ll have to navigate.
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5. Assuming that your Part D plan will always offer the best prices on your medications
Part D plans cover many prescription medications, but copays and coinsurance amounts for covered medications can vary widely. That’s why it’s always smart to check GoodRx to see if you can get your medication for a lower price with a discount. While the GoodRx price won’t always beat what you’d pay with Plan D cost-sharing, in many instances using a coupon can allow you to pay less out of pocket. Though, what you spend probably won’t count toward your Part D out-of-pocket maximum.
6. Leaving benefits on the table
Did you know that some Medicare Advantage plans offer gym or wellness benefits, or that some will cover transportation to your medical appointments? Many people are unaware of these perks, as well as the fact that Medicare Part B and Medicare Advantage cover acupuncture for chronic low back pain. Take the time to review your coverage details so you can use all of your benefits.
7. Not considering your out-of-pocket costs
With original Medicare, you won’t have an annual cap on out-of-pocket spending. For this reason, some enrollees purchase Medigap supplement insurance to pay for deductibles, copays, coinsurance, and other out-of-pocket costs. The 10 nationally standardized Medigap plans offer a variety of different benefits.
Medicare Advantage plans must have out-of-pocket spending limits. In 2026, the out-of-pocket spending maximums for Medicare Advantage plans are:
$9,250 for in-network covered services
$13,900 for in-network and out-of-network covered services combined
The 2027 out-of-pocket limits for Medicare Advantage plans have been set at:
$9,850 for in-network covered services
$14,800 for in-network and out-of-network covered services combined
It’s important to note that most Medicare Advantage enrollees do not reach the annual out-of-pocket limits.
8. Assuming you have to keep the same coverage forever
Enrolling in either original Medicare or Medicare Advantage doesn’t have to be a lifelong commitment. The plan that works for you when you first enroll might not be the best fit 5 or 10 years down the road.
You may consider switching if you find that your plan isn’t providing the coverage you need. You can make changes during the annual Medicare open enrollment period (October 15 through December 7). If you have a Medicare Advantage plan, you can also make changes during Medicare Advantage open enrollment (January 1 through March 31). Just be aware of the potential challenges if you want to switch from Medicare Advantage to original Medicare — especially if you intend to buy a Medigap plan. You could be denied Medigap coverage, which can make original Medicare unaffordable.
9. Assuming that one coverage solution fits all
Newcomers to Medicare often opt for the same plan that a loved one or close friend has chosen — simply because that person is happy with their coverage. But when it comes to health insurance, your needs may not match those of your spouse, sibling, or best friend. That’s why it’s important to pay close attention to coverage details when choosing between original Medicare and Medicare Advantage, selecting Part D coverage, or buying a Medigap plan if you have original Medicare.
10. Signing up for Medicare when you’re still planning to contribute to your HSA
If you want to continue contributing to a health savings account (HSA), you will need to delay your enrollment in Medicare, including Part A. While you will still be able to use the funds in your HSA once you begin receiving Medicare benefits, you are forbidden from making additional contributions to your account once you are enrolled.
How to avoid these Medicare pitfalls
Here are ways to prepare for Medicare open enrollment — and avoid the Medicare pitfalls listed above:
Take action during your 7-month initial enrollment period, or as soon as you lose Medicare-equivalent coverage.
Consider whether the plan you want to enroll in, or are currently enrolled in, fits your health needs.
Whether it’s your first time joining a Medicare plan or you’re making changes to your coverage, make sure you have all the documents you’ll need to enroll online, by phone, or in person.
Figure out whether or not you’ll need a Medigap supplement plan, which is only available with original Medicare. If so, sign up during your Medigap open enrollment period, which is the first 6 months you are 65 or older and enrolled in Medicare Part B.
Contact 1-800-MEDICARE (1-800-633-4227) or your State Health Insurance Assistance Program (SHIP) for free help.
Frequently asked questions
Medicare doesn’t cover long-term care. Many people are unprepared for this expense if they don’t have access to Medicaid, which does offer coverage for nursing home care and assisted living.
Original Medicare doesn’t cover most vision, dental, and hearing care, though many Medicare Advantage plans offer limited benefits in these areas. Medicare also doesn’t cover absorbent incontinence products, such as adult diapers and pads.
A 2026 federal report raised alarms about Medicare Advantage plans and prior authorization denials involving long-term acute care and inpatient rehabilitation for people recovering from illness or injury. The three largest Medicare Advantage providers by enrollment — CVS Health, UnitedHealthcare, and Humana — had the highest rates of coverage denial.
A companion report highlighted the high rates of overturned denials — 95% of those that were appealed — and raised questions about the initial coverage refusals for skilled nursing facility care for people recovering from illness, injury, or surgery.
Your selected coverage and annual premiums will determine your Medicare upfront costs. Most people don’t pay a Part A premium, but you will be charged for Part B based on income. You will pay for Part B whether you are enrolled in Medicare Advantage or original Medicare. If you go with Medicare Advantage, you may have an additional premium, depending on the plan you choose.
If you enroll in original Medicare, you will have to pay extra for a Part D standalone plan if you want prescription coverage. With Medicare Advantage, you may be charged more for a plan that includes Part D coverage. High earners pay premium surcharges for Part B and Part D.
You will also have an additional premium if you choose to pair original Medicare coverage with a Medigap plan.
Medicare doesn’t cover long-term care. Many people are unprepared for this expense if they don’t have access to Medicaid, which does offer coverage for nursing home care and assisted living.
Original Medicare doesn’t cover most vision, dental, and hearing care, though many Medicare Advantage plans offer limited benefits in these areas. Medicare also doesn’t cover absorbent incontinence products, such as adult diapers and pads.
A 2026 federal report raised alarms about Medicare Advantage plans and prior authorization denials involving long-term acute care and inpatient rehabilitation for people recovering from illness or injury. The three largest Medicare Advantage providers by enrollment — CVS Health, UnitedHealthcare, and Humana — had the highest rates of coverage denial.
A companion report highlighted the high rates of overturned denials — 95% of those that were appealed — and raised questions about the initial coverage refusals for skilled nursing facility care for people recovering from illness, injury, or surgery.
Your selected coverage and annual premiums will determine your Medicare upfront costs. Most people don’t pay a Part A premium, but you will be charged for Part B based on income. You will pay for Part B whether you are enrolled in Medicare Advantage or original Medicare. If you go with Medicare Advantage, you may have an additional premium, depending on the plan you choose.
If you enroll in original Medicare, you will have to pay extra for a Part D standalone plan if you want prescription coverage. With Medicare Advantage, you may be charged more for a plan that includes Part D coverage. High earners pay premium surcharges for Part B and Part D.
You will also have an additional premium if you choose to pair original Medicare coverage with a Medigap plan.
The bottom line
When enrolling in original Medicare or Medicare Advantage, a Part D plan, or Medigap supplement insurance, review your coverage options and consider how well they align with your health needs and budget. Your choices will affect your premiums and what you pay out of pocket when you need care.
With original Medicare or Medicare Advantage, you will pay a Part B premium. Choosing original Medicare may give you the widest access to healthcare professionals, but it will also come with additional premiums if you want Part D and/or Medigap coverage. Medicare Advantage plans often include extra benefits, but they may provide more limited access to health professionals, hospitals, and recommended care. You also may be charged an additional monthly cost — beyond your Part B premium — with a Medicare Advantage plan.
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References
Centers for Medicare & Medicaid Services. (2024). Information partners can use on: The Part D late enrollment penalty.
Centers for Medicare & Medicaid Services. (2026). 5 things you need to know about signing up for Medicare.
Innes, G. K., et al. (2024). Prescription medication use among older adults in the US. JAMA Internal Medicine.
KFF. (2025). There are a lot of Medicare Advantage plan options in my area. How do I decide which plan is best for me?
Medicare.gov. (n.d.). Acupuncture.
Medicare.gov. (n.d.). Avoid late enrollment penalties.
Medicare.gov. (n.d.). Get ready to buy: Your Medigap open enrollment period.
Medicare.gov. (n.d.). How Medicare works with other insurance.
Medicare.gov. (n.d.). Retiree insurance & Medicare.
Medicare.gov. (n.d.). ‘Welcome to Medicare’ package (not automatically enrolled).
Medicare.gov. (n.d.). When can I sign up for Medicare?
Medicare.gov. (n.d.). When does Medicare coverage start?
Medicare.gov. (n.d.). Working past 65.
Medicare Interactive. (2025). Health savings accounts (HSAs) and Medicare.
U.S. Department of Health and Human Services Office of Inspector General. (2026). Medicare Advantage organizations overturned nearly all appealed prior authorization denials for skilled nursing facility admission, raising concerns about initial denials.
U.S. Department of Health and Human Services Office of Inspector General. (2026). The three largest Medicare Advantage organizations denied requests for long-term acute care and inpatient rehabilitation at some of the highest rates.
Yeh, H. (2026). Understanding your Medicare Advantage costs: Premiums, deductibles and out-of-pocket maximums. MedicareGuide.com.
