Here's something that catches people off guard every year: you can't just buy health insurance whenever you want. There's a specific window each fall and winter when you can sign up, switch plans, or make changes to your coverage. Miss that window, and you could be stuck without insurance—or paying for a plan that doesn't work for you—for an entire year.
That window is called open enrollment, and understanding how it works is crucial for protecting your health and your wallet. Whether you're buying insurance for the first time, switching from an employer plan to the marketplace, or just want to make sure you're getting the best deal, this guide will walk you through everything you need to know.
When Does Open Enrollment Happen?
For marketplace health insurance in most states, the 2025 open enrollment period ran from November 1, 2024 through January 15, 2025. But here's where timing really matters: if you wanted your coverage to start on January 1, you needed to enroll by December 15. Anyone who enrolled between December 16 and January 15 had coverage starting February 1.
Think of it this way: open enrollment is like concert ticket sales with different tiers. The earlier you act, the sooner you're covered. Wait until the last minute, and you'll have a gap in your coverage when the new year starts.
It's worth noting that some states run their own marketplaces with slightly different dates, so if you're in California, New York, or another state with its own exchange, check your state's specific timeline. Employer-sponsored open enrollment periods vary by company, typically happening in the fall, but your HR department will give you specific dates.
What You Can Actually Do During Open Enrollment
Open enrollment isn't just for people who don't have insurance. Even if you're perfectly happy with your current plan, this is your annual chance to make changes without needing a special reason. During open enrollment, you can:
Enroll in a health plan for the first time. Maybe you just aged out of your parents' plan at 26, left a job with benefits, or simply haven't had coverage before. Open enrollment is your opportunity to get insured without needing a qualifying life event.
Switch to a different plan. Your needs change. Maybe you're planning to start a family and need better maternity coverage. Maybe your regular doctor isn't in your network anymore. Or maybe there's simply a cheaper plan that covers what you need. Open enrollment lets you shop around.
Update your existing coverage. Even if you're keeping the same plan, you should review it every year. Premiums, deductibles, and covered services can all change. In 2025, 42% of marketplace enrollees qualified for plans with $0 monthly premiums after subsidies—you might be one of them if your income changed.
Add or remove dependents. Had a baby? Your teenager turned 26? Got married or divorced? Open enrollment is when you can adjust who's covered under your plan.
What Happens If You Miss the Deadline
This is where open enrollment gets serious. If you miss the January deadline and you don't qualify for an exception, you're generally out of luck until the next open enrollment period. That means potentially going without coverage for almost a year, which is both risky and potentially expensive if you do need medical care.
But there's a safety net: special enrollment periods. If you experience certain qualifying life events, you get a 60-day window to enroll in coverage even outside the standard open enrollment period. The most common qualifying events include getting married, having or adopting a baby, losing other health coverage (like when you leave a job), moving to a new area, or turning 26 and aging out of a parent's plan.
If you lose Medicaid or CHIP coverage, you actually get 90 days to enroll in a marketplace plan. And if you're below certain income levels, you might qualify for Medicaid year-round—there's no open enrollment period for Medicaid in most states.
What if you miss the deadline and don't qualify for a special enrollment period? You have limited options. Short-term health insurance plans are available in many states, but they don't have to cover pre-existing conditions or provide the comprehensive benefits that ACA marketplace plans include. They're better than nothing, but they're not a full substitute for real health insurance.
How to Make the Most of Open Enrollment
Here's what most people get wrong about open enrollment: they treat it like renewing a subscription, just clicking through without paying attention. But insurance plans change every year. Your income might have changed, which affects your subsidies. New plans might be available. Your current plan's costs and coverage could be completely different from last year.
Start by estimating your household income for the coming year as accurately as possible. This determines your subsidy eligibility. In 2025, nearly 24 million people enrolled in marketplace coverage, and a huge percentage qualified for financial assistance that made coverage affordable or even free. You won't know if you're eligible unless you provide accurate income information.
Next, think about your actual healthcare needs. Are you generally healthy and just need catastrophic coverage? Do you have regular prescriptions that need to be covered? Do you have specific doctors you want to keep seeing? Don't just look at the monthly premium—check the deductible, copays, and whether your doctors and medications are covered.
Compare at least three different plans. A bronze plan with a low premium might cost you thousands more out of pocket if you actually use your insurance. A gold plan with a higher monthly payment might save you money overall if you have regular medical expenses. The marketplace calculator tools can help you estimate total costs, not just premiums.
Getting Started With Your Enrollment
If you're enrolling through the federal marketplace at HealthCare.gov or your state's marketplace, create your account early. You'll need information about your household income, including W-2s or pay stubs if you're currently employed, or tax returns if you're self-employed. Have your Social Security number ready, along with information for anyone in your household you want to cover.
The application will determine if you're eligible for subsidies or if you qualify for Medicaid instead. Then you can browse plans, compare coverage, and enroll. Once you select a plan, you'll need to pay your first month's premium by the due date for your coverage to actually start.
Don't wait until January 15 to start this process. Give yourself time to compare options, ask questions, and make an informed decision. And if you're confused, help is available—marketplace navigators and licensed insurance agents can guide you through the process at no cost to you.
Open enrollment only comes around once a year, so treat it as an important financial decision—because that's exactly what it is. A few hours of research now can save you thousands of dollars and ensure you have the coverage you need when health issues arise.
