Medicare Mistakes to Avoid
Common (and Not So Common) Medicare Mistakes
Most Medicare mistakes don’t happen because people are careless. They happen because the rules are confusing — and the consequences aren’t obvious until it’s too late.
Some of these mistakes are well known. Others catch even experienced professionals off guard.
Here are the ones that matter most — and how to avoid them.
No pressure. Just protection against costly errors.
The Mistakes Everyone Warns About
These are the most frequently made Medicare errors. They’re well documented — but they still happen every day.
Assuming COBRA Counts as Employer Coverage
COBRA lets you continue your employer health plan after leaving a job — but Medicare does not consider it creditable employer coverage. If you rely on COBRA instead of enrolling in Part B, you may face a permanent late enrollment penalty.
Missing the Initial Enrollment Window
Your Initial Enrollment Period is a 7-month window around your 65th birthday. If you don’t sign up during this time (and don’t have qualifying coverage), you may have to wait until the General Enrollment Period — and your coverage won’t start until July 1.
Skipping Part D Because You Don’t Take Medications
You may not need prescriptions today — but if you delay Part D enrollment without creditable drug coverage, the penalty compounds for every month you’re uncovered. The longer you wait, the more you’ll pay permanently when you finally enroll.
Choosing a Plan Based Only on Premium
A $0 premium plan sounds attractive — but it doesn’t account for copays, deductibles, drug costs, or out-of-pocket maximums. Two plans with identical premiums can cost thousands of dollars apart over a year depending on your doctors, medications, and usage patterns.
Not Reviewing Your Plan Every Year
Medicare plans can change their networks, formularies, copays, and benefits every January 1. A plan that was perfect last year may no longer cover your doctors or medications — and you won’t know unless you review it.
Missing the Medigap Open Enrollment Window
Your Medigap Open Enrollment Period is a one-time, 6-month window starting when you’re 65 and enrolled in Part B. During this time, no insurer can deny you or charge more based on health. After it closes, most states allow medical underwriting — which means you could be denied or pay significantly more.
Those are the mistakes most people have heard about.
The next ones? They often come as a surprise.
The Mistakes That Catch People Off Guard
These errors are less talked about — but equally costly. Even advisors sometimes miss them.
Working for a Small Employer and Assuming You Can Delay Part B
If your employer has fewer than 20 employees, Medicare becomes your primary insurance at 65 — even if you’re still working. Delaying Part B in this situation doesn’t protect you from penalties, and your employer plan may not pay as expected because it assumes Medicare is covering its share first.
Not Realizing Retiree Coverage Isn’t the Same as Active Employer Coverage
Some employers offer retiree health benefits — but this coverage is not the same as active employee coverage. Retiree benefits typically expect Medicare to be your primary payer. If you delay Part B enrollment based on retiree coverage, you may face penalties and gaps.
Switching from Advantage to Supplement Without Understanding Underwriting
If you’ve been on a Medicare Advantage plan and want to switch to a Supplement plan, you may need to go through medical underwriting — especially if your Medigap Open Enrollment window has already passed. Health conditions that didn’t matter on Advantage could result in denial or significantly higher premiums for a Supplement policy.
Not Checking If Your Pharmacy Is in the Plan’s Preferred Network
Part D and Advantage plans often have preferred pharmacy networks. You may pay significantly more — sometimes double — for the same medication at a non-preferred pharmacy, even if it’s technically in-network. This is separate from the drug formulary and rarely discussed during enrollment.
Enrolling in an HSA-Eligible Plan After Starting Part A
Once you’re enrolled in any part of Medicare — including Part A, which many people receive automatically at 65 — you are no longer eligible to contribute to a Health Savings Account. If you or your employer continue HSA contributions after Part A begins, you could face IRS tax penalties.
Canceling Your Current Plan Before the New One Is Confirmed
When switching plans, some people proactively cancel their old coverage before the new enrollment is officially processed. If the new enrollment is delayed or denied, you could be left with no coverage at all — and may not be able to re-enroll until the next enrollment period.
Not Understanding How IRMAA Affects Your Premiums
If your income exceeded certain thresholds two years ago, you may be paying significantly more for Part B and Part D through IRMAA (Income-Related Monthly Adjustment Amount). Many people don’t realize this surcharge exists until they see a larger-than-expected Social Security deduction — and don’t know it can be appealed after life-changing events like retirement.
Assuming Your Spouse’s Employer Coverage Protects You
If you’re covered under your spouse’s employer plan, the same 20-employee rule applies — but it’s your spouse’s employer that must have 20+ employees, not yours. If your spouse works for a small company, their plan may not protect you from Part B penalties, even though you’re technically covered.
Forgetting That Medicare Advantage Plans Change Every Year
Plan benefits, formularies, provider networks, copays, and out-of-pocket maximums can all change on January 1 — even if you stay on the same plan. A doctor who was in-network last year may not be this year. A drug that was Tier 2 may move to Tier 4. Staying on “the same plan” doesn’t mean staying on the same coverage.
Moving to a New State Without Reviewing Your Plan
Medicare Advantage and Part D plans are ZIP code-specific. If you move — even within the same state — your current plan may no longer be available in your new area. Your doctors may be out of network. Your prescriptions may not be covered. Moving triggers a Special Enrollment Period, but only for a limited time.
Trusting a TV Ad or Mailer to Find the “Best Plan”
Medicare advertising during enrollment season is aggressive. Commercials and mailers often promote high-giveback amounts, $0 premiums, or extra benefits — without disclosing network restrictions, coverage limitations, or copay structures. These ads are designed to drive enrollment calls, not to help you compare total plan value.
Not Knowing That Original Medicare Has No Out-of-Pocket Maximum
Many people choose Original Medicare without realizing that it has no annual cap on what you can spend out of pocket. Part B’s 20% coinsurance has no ceiling — meaning a serious illness or prolonged treatment could result in tens of thousands of dollars in costs. This is one of the primary reasons Supplement plans exist.
The Pattern Behind Every Mistake
Nearly every Medicare mistake shares the same root cause:
People apply what they know about employer insurance to a system that works completely differently.
Medicare requires a different mindset. The best way to avoid mistakes is to review your situation with someone who understands the rules.
We Help You Get It Right the First Time
During your free Medicare review, we:
Evaluate your enrollment timeline and identify penalty risks
Confirm whether employer or retiree coverage qualifies
Check your doctors and prescriptions across all available plans
Compare total yearly cost — not just premiums
Explain Medigap enrollment windows and underwriting rules
Coordinate Part A, Part B, Part D, and plan timing
If your coverage is correct — we’ll confirm that.
If a change would protect you — you’ll understand exactly why.
Frequently Asked Questions
Can Medicare mistakes be fixed?
Some can. Enrollment penalties can sometimes be appealed with proper documentation. Coverage gaps may be resolved during a Special Enrollment Period. But many mistakes — particularly late enrollment penalties — are permanent. Prevention is always better than correction.
Who is responsible for making sure I enroll correctly?
Ultimately, you are. Medicare does send reminders, and employers have some notification obligations, but the responsibility to enroll on time and choose the right coverage falls on the individual. Working with a licensed independent advisor can help you navigate the process correctly.
Is COBRA ever useful with Medicare?
COBRA can provide temporary coverage for things Medicare doesn’t cover (like dental or vision), but it should not be relied upon as a substitute for Medicare enrollment. COBRA does not protect you from Part B late enrollment penalties.
How do I know if my coverage is “creditable”?
For Part B, creditable coverage generally means active employer group coverage from a company with 20+ employees. For Part D, your employer or plan should send you a written notice each year confirming whether your drug coverage meets the creditable standard. If you haven’t received that notice, it’s worth asking.
What’s the single most important deadline to know?
The Medigap Open Enrollment Period. Unlike most other deadlines, there is no penalty for missing it — but the consequence can be just as severe: being denied Supplement coverage entirely, or paying significantly higher premiums based on your health history. And unlike penalties, there’s no appeal process for underwriting denial.
Should I use a call center or 1-800 number to enroll?
Be cautious. Many 1-800 numbers and TV ad hotlines connect you to agents who represent a single carrier and are incentivized to sell specific plans. An independent advisor compares plans across multiple carriers based on your specific needs.
What if I already think I made a mistake?
It’s worth reviewing as soon as possible. Some mistakes can be corrected during a Special Enrollment Period, and certain penalties can be appealed. The sooner you act, the more options you have. Schedule a free review.
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📘Complete Medicare Guide
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💊Part D Coverage
Prescription drug plans and formularies.
📖Medicare Glossary
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Not Sure If You’ve Made a Medicare Mistake?
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