Your Medicare plan worked perfectly well this year, so why bother changing anything for 2027? That assumption could become an expensive mistake for retirees who overlook changes to prescription drug coverage, provider networks, and out-of-pocket expenses. Even if your monthly premium stays the same, the amount you spend on medical care could look very different next year. With Medicare Open Enrollment already underway, millions of Americans have an opportunity to review their coverage before those changes take effect.
The average Medicare Advantage premium is projected to decline 16.5% in 2027, but individual plan costs and benefits can still change. Avoiding these seven Medicare Open Enrollment mistakes could help retirees protect their savings and prevent unpleasant surprises when they need medical care.
1. Assuming Your Current Medicare Plan Will Stay the Same
One of the most common Medicare Open Enrollment mistakes is automatically renewing coverage without reviewing what’s changing. Every fall, Medicare Advantage and Part D plans send members an Annual Notice of Change explaining adjustments to premiums, deductibles, benefits, and other coverage details.
Beneficiaries should have received this notice in September and should also review it before making decisions for the following year. A plan that covered your medications affordably in 2026 might have different copayments or coverage restrictions in 2027, even if its name hasn’t changed. Take 15 minutes to compare your notice with your current benefits rather than assuming everything will carry over unchanged.
2. Choosing the Plan With the Lowest Monthly Premium
A Medicare Advantage plan advertising a $0 monthly premium can sound especially attractive when you’re living on a fixed retirement income. However, that advertised premium doesn’t eliminate your Medicare Part B premium or guarantee that your overall medical expenses will be low. Depending on the plan, you may still face deductibles, specialist copayments, hospital charges, and other out-of-pocket expenses.
For example, saving $25 per month on premiums amounts to $300 annually, but several expensive specialist visits or a hospital stay could erase those savings. Use the Medicare Plan Finder to compare estimated total costs, including premiums and potential cost-sharing, rather than selecting coverage based on one attractive number.
3. Forgetting to Check Whether Your Prescriptions Are Covered
Prescription drug coverage deserves particular attention because Medicare Part D costs are changing again in 2027. The maximum annual deductible increases from $615 in 2026 to $700 in 2027, while the annual out-of-pocket threshold for covered Part D drugs rises from $2,100 to $2,400.
However, that threshold doesn’t mean every beneficiary will spend $2,400, and premiums or medications excluded from coverage may create additional expenses. A plan can also change its formulary, preferred pharmacies, drug tiers, and utilization management requirements, potentially affecting medications you’ve taken for years. Before renewing, enter your complete medication list, dosages, and preferred pharmacy into Medicare’s comparison tool to estimate what your prescriptions could actually cost.
4. Not Confirming That Your Doctors Are Still In-Network
Keeping your preferred doctors can be just as important as finding an affordable monthly premium. Medicare Advantage plans commonly use provider networks, and participating physicians, hospitals, and specialists may change from one year to the next. The Medicare Rights Center recommends checking whether your providers and pharmacies will remain in-network for 2027 before choosing coverage.
Imagine discovering in January that the cardiologist you’ve seen for a decade no longer participates in your plan, potentially forcing you to switch providers or face higher costs depending on your coverage. Contact both the insurance company and your doctor’s office to verify participation in the specific 2027 plan you’re considering.
5. Switching From Original Medicare Without Understanding Medigap Rules
Another costly mistake involves moving from Original Medicare with a Medicare Supplement Insurance policy, commonly called Medigap, into Medicare Advantage without considering the long-term consequences. Although Medicare Advantage may offer additional benefits and lower advertised premiums, returning to Original Medicare later doesn’t always guarantee that you can purchase the same Medigap coverage again. Beneficiaries may face restrictions when attempting to re-enroll in Medigap after leaving it. Outside certain guaranteed-issue situations and state-specific protections, insurers may use medical underwriting or decline applications based on health history.
Before switching, investigate your state’s Medigap rules and understand what options would remain available if your healthcare needs changed.
6. Overlooking Free Help That Could Lower Your Costs
Many retirees spend hours comparing Medicare plans without realizing that free, personalized assistance is available. State Health Insurance Assistance Programs, commonly known as SHIPs, provide unbiased Medicare counseling to help beneficiaries understand coverage options, enrollment rules, and potential financial assistance.
Counselors can also help identify whether someone may qualify for programs such as Medicare Savings Programs or Part D Extra Help, which can reduce certain healthcare expenses for eligible individuals. For example, a retiree struggling with prescription costs might discover that an assistance program could make a significant difference in their monthly budget.
Visit SHIP’s national website or contact 1-800-MEDICARE to find reliable guidance before making a coverage decision.
7. Missing the December 7 Enrollment Deadline
Perhaps the most frustrating of all Medicare Open Enrollment mistakes is finding a better plan but failing to enroll before the deadline. The annual Medicare Open Enrollment Period runs from October 15 through December 7, 2026, with coverage changes generally taking effect January 1, 2027. Beneficiaries can use this period to switch Medicare Advantage plans, change Part D plans, or move between Original Medicare and Medicare Advantage, subject to applicable coverage rules.
Although Medicare Advantage members have a separate enrollment period from January 1 through March 31, that opportunity has different restrictions and isn’t a universal second chance for every beneficiary. Waiting until the final evening to compare coverage, contact insurers, or submit paperwork increases the risk of missing an opportunity to make a beneficial change.
A Little Homework Now Could Protect Your 2027 Retirement Budget
Medicare Open Enrollment isn’t simply an annual paperwork requirement; it’s an opportunity to make sure your health coverage still matches your medical needs and financial circumstances. The cheapest-looking plan isn’t always the most affordable, and keeping last year’s coverage without reviewing changes can expose you to unexpected expenses. Start with your Annual Notice of Change, then compare prescriptions, provider networks, deductibles, premiums, and potential out-of-pocket costs for 2027. If you’re uncertain about your options, use Medicare’s official comparison tools or speak with a SHIP counselor before the December 7 deadline. Avoiding these Medicare Open Enrollment mistakes could help you enter 2027 with greater confidence that your healthcare coverage won’t unnecessarily strain your retirement savings.
Have you reviewed your Medicare coverage for 2027 yet, or have you ever discovered an unexpected premium increase, prescription cost, or network change after Open Enrollment ended? Share your experience in the comments.
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