Common Medicare Mistakes and How to Avoid Them

1. Missing the Medigap Open Enrollment Window

Your six-month Medigap Open Enrollment Period begins the first day of the month you are both 65 or older and enrolled in Medicare Part B. During this window, insurers must sell you any Medigap policy they offer in your state — regardless of your health history. After it closes, medical underwriting may apply, and you may be denied coverage or charged significantly more.

Many retirees do not learn about this window until after it has passed. The mistake is not choosing the "wrong" plan — it is not knowing the window existed at all. If you are approaching 65, research Medigap options before your enrollment period begins.

2. Assuming COBRA Protects Your Medicare Enrollment Rights

COBRA allows you to continue employer coverage temporarily after leaving a job. However, COBRA is generally not considered "coverage based on current employment" for Medicare purposes. If you turn 65 and delay Medicare Part B enrollment because you have COBRA, you may face a late enrollment penalty when you eventually sign up — and you will not receive a Special Enrollment Period.

The safe approach: if you are leaving employment at or after age 65, enroll in Medicare during your Initial Enrollment Period regardless of COBRA availability.

3. Choosing a Plan Based Solely on Premium

A $0-premium Medicare Advantage plan is appealing on its face. But the premium is one line in a much larger equation. Copayments, coinsurance, deductibles, network restrictions, prior authorization requirements, and out-of-pocket maximums all affect the true cost of a plan.

Similarly, the lowest-premium Medigap plan is not necessarily the best value. Insurers use different pricing methods (attained-age, issue-age, or community-rated), and a plan that is cheapest today may not remain so over time. Compare total expected annual costs — not just the monthly premium.

4. Not Checking Provider Networks Before Enrolling

If you join a Medicare Advantage plan, your provider network matters. HMO plans generally require you to use in-network providers except in emergencies. PPO plans offer more flexibility but at higher out-of-network costs. Before enrolling in any Medicare Advantage plan, verify that your current doctors, specialists, and preferred hospitals are in the plan's network.

Networks can change from year to year. A provider who is in-network this year may not be next year. Check annually, not just at initial enrollment.

5. Ignoring Part D or Delaying Enrollment

Even if you do not take prescription medications today, delaying Part D enrollment without creditable drug coverage elsewhere can result in a permanent late enrollment penalty. The penalty is calculated based on the number of months you were without creditable coverage and is added to your Part D premium for as long as you have a Medicare drug plan.

The logic is straightforward: healthy people not enrolling in Part D until they get sick would undermine the risk pool. The penalty incentivizes continuous enrollment. Whether or not you need medications now, evaluate whether enrolling in a low-cost Part D plan is worth the penalty avoidance.

The Common Thread

Each of these mistakes shares a root cause: insufficient information at the time of the decision. Medicare is complex, and the consequences of certain choices can extend years into the future. The best protection is education before enrollment — not after.

"In Medicare, the cost of a mistake is usually not immediate — it shows up months or years later, when the window to correct it has already closed."