Medicare Education
What Are the 7 Most Common Medicare Mistakes?
These 7 Medicare mistakes cost people thousands of dollars and permanent premium penalties. The most expensive error, missing your Medigap Open Enrollment window, can result in being denied coverage entirely. According to CMS, nearly 1 in 5 new enrollees makes at least one costly mistake. Here's how to avoid every one of them.
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1Missing Your Medigap Open Enrollment Window
The Mistake
Your Medigap Open Enrollment Period is the 6-month window starting when you turn 65 AND are enrolled in Part B. During this time, insurance companies cannot deny you coverage or charge higher premiums based on health conditions.
The Consequence
If you miss this window and later decide you want a Medicare Supplement plan, companies can use medical underwriting. Pre-existing conditions could mean higher premiums or outright denial. According to KFF, up to 30% of applicants outside open enrollment are denied.
How to Avoid It
Mark your calendar. If you're turning 65, explore Medigap options during this window even if you're not sure you want one yet. It's a one-time opportunity you can't get back.
2Not Signing Up for Part B When First Eligible
The Mistake
If you don't enroll in Part B during your Initial Enrollment Period (3 months before to 3 months after your 65th birthday) and don't have qualifying employer coverage, you'll face a Late Enrollment Penalty.
The Consequence
The penalty is 10% of the standard premium ($202.90 in 2026) for every 12-month period you could have had Part B but didn't. This penalty is permanent, you pay it for the rest of your life.
How to Avoid It
If you have employer coverage through your (or your spouse's) current employer with 20+ employees, you're exempt. Otherwise, sign up during your Initial Enrollment Period. No exceptions.
3Choosing a Plan Based on Premium Alone
The Mistake
A $0 premium Medicare Advantage plan sounds great, but it doesn't mean $0 costs. You'll pay copays, coinsurance, and deductibles every time you use care.
The Consequence
A "free" plan could cost you $3,000 to $8,300 in out-of-pocket expenses if you need surgery, specialist visits, or hospital stays. The out-of-pocket maximum can be as high as $8,300 in 2026.
How to Avoid It
Look at the total cost of a plan - premium + expected out-of-pocket costs. A plan with a higher premium and lower cost-sharing may save you money overall. This is why working with an independent broker is valuable.
4Not Checking if Your Doctors Are in Network
The Mistake
Medicare Advantage plans use provider networks (HMO or PPO). If your doctors aren't in the plan's network, you may not be covered - or you'll pay significantly more.
The Consequence
You could be forced to switch doctors, pay full price for out-of-network visits, or delay care while finding new providers. According to CMS, network changes affect about 15% of Advantage enrollees each year.
How to Avoid It
Before enrolling in any Advantage plan, check the provider directory. Make sure your primary care doctor, specialists, and preferred hospital are all in-network. Networks change annually.
5Forgetting to Review Your Plan Every Year
The Mistake
Medicare plans change every year. Premiums, copays, drug formularies, and provider networks can all change from one year to the next - even if you don't change plans.
The Consequence
A drug that was covered this year might not be covered next year. A doctor in your network this year might be out of network next year. You could be paying more for less coverage without realizing it.
How to Avoid It
Review your plan during the Annual Election Period (October 15, December 7) every year. Compare it to other available plans.
6Not Entering All Your Medications When Comparing Plans
The Mistake
When comparing Medicare Advantage or Part D plans, people often forget to enter all their medications - including dosage and pharmacy preference.
The Consequence
You could end up on a plan that doesn't cover one of your medications, places it in a high-cost tier, or requires prior authorization. This could mean hundreds or thousands of dollars in unexpected drug costs.
How to Avoid It
Make a complete list of every medication you take, including dosage and frequency. Enter ALL of them when comparing plans. With the new $2,100 Part D out-of-pocket cap in 2026, drug coverage is more important than ever.
7Assuming Medicare Covers Everything
The Mistake
Original Medicare (Parts A & B) has significant gaps. It doesn't cover dental, vision, hearing, most prescription drugs, or long-term care. And there's no out-of-pocket maximum.
The Consequence
Without supplemental coverage, a serious illness or extended hospital stay could result in catastrophic out-of-pocket costs. Part A alone has a $1,736 deductible per benefit period in 2026, and Part B has 20% coinsurance with no cap.
How to Avoid It
Understand what Medicare does and doesn't cover. Consider either a Medicare Advantage plan (which adds benefits and includes an out-of-pocket max) or a Medicare Supplement + Part D combination for comprehensive protection.
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