The short answer
The biggest open enrollment mistake, for both Medicare and ACA coverage, is doing nothing and letting your plan auto-renew without reviewing it. Plans change their costs, networks, formularies, and benefits each year, and being automatically re-enrolled into a plan that no longer fits can quietly raise your costs or drop your providers. Other mistakes include choosing on premium alone, missing the enrollment deadline, and not checking that your doctors and drugs are still covered. Reviewing your coverage every year during open enrollment is the fix.
So the biggest open enrollment mistake is letting your plan auto-renew without reviewing whether it still fits after annual changes.
The mistakes to avoid
Watch for passively accepting auto-renewal without comparing options; choosing a plan by premium alone rather than total cost; missing the open enrollment deadline, which can lock you out until next year; and not verifying that your doctors, hospitals, and medications are still covered under the renewed plan. Because plans change annually, last year's good choice may not fit now. Our guides to ACA auto-reenrollment and switching Medicare Advantage plans during AEP cover reviewing your coverage.
The theme is actively reviewing your plan each year rather than coasting on auto-renewal or premium alone.
How to get it right
Each year during open enrollment, review your current plan's changes, compare it against other options based on your doctors, medications, and total cost, and make a deliberate choice before the deadline. Confirm your providers and drugs are still covered. A local licensed advisor can compare current options at no cost. Our Medicare overview and ACA health insurance page cover the annual review. This is educational information.
The takeaway: avoid open enrollment mistakes by actively reviewing your plan against your needs each year and choosing deliberately before the deadline, rather than letting it auto-renew.
Frequently Asked Questions
What is the biggest open enrollment mistake?
Doing nothing and letting your plan auto-renew without reviewing it. Plans change costs, networks, and benefits each year, so auto-renewal can leave you in a plan that no longer fits.
Why should I review my plan every open enrollment?
Because plans change their pricing, networks, formularies, and benefits annually, a plan that fit last year may cost more or drop your providers, so reviewing keeps your coverage aligned with your needs.
What happens if I miss open enrollment?
You may be locked into your current plan or lose coverage options until the next enrollment period, absent a qualifying special enrollment event, so meeting the deadline matters.
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