Key Takeaways
- Auto-renewal locks you into last year's plan even if costs, coverage, or your health needs have changed significantly.
- Formulary and network changes take effect January 1st — verifying them before you enroll can prevent denied claims.
- Missing the open enrollment deadline typically means waiting a full year unless you qualify for a special enrollment period.
- Choosing a plan based on premium alone often leads to much higher total annual costs than a slightly pricier plan.
- Dependent coverage, FSA elections, and HSA contributions all require active decisions — they don't carry forward automatically.
- Reviewing your Summary of Benefits and Coverage (SBC) document before enrolling takes about 20 minutes and can save thousands.
Why Open Enrollment Is Harder Than It Looks
Open enrollment is the one window each year when you can make changes to your health insurance without needing a qualifying life event. For most employer plans, that window is just two to four weeks — and for ACA Marketplace plans, it runs from November 1 through January 15 in most states. Sounds manageable. But every year, millions of people make decisions they regret, or worse, make no decision at all and get locked into coverage that no longer fits their lives.
The frustrating part? Most of these mistakes are entirely preventable. They happen not because people are careless, but because the process is designed in ways that reward inaction and bury critical details in dense plan documents. I've spent years helping employees navigate their benefits, and the same pitfalls come up again and again. This guide walks through each one — what it is, why it trips people up, and exactly what to do instead.
If you're enrolling a spouse, children, or other dependents, the stakes are even higher. See our guide to family enrollment decisions for a deeper look at coordinating coverage across a household.
The Most Common Open Enrollment Mistakes — And How to Avoid Them
Let's get into the specific errors that catch people off guard. These aren't obscure edge cases — they're the routine mistakes that show up in HR inboxes every February when people realize something went wrong. Read through all of them even if some seem obvious. The details in the "how to avoid" sections are where the real value is.
Letting auto-renewal choose your plan without reviewing what changed.
Why it happens: Doing nothing feels safe, and most enrollment portals make inaction easy. People assume their plan is "good enough" because it worked last year.
Choosing a health plan based on monthly premium alone without calculating total annual cost.
Why it happens: The premium is the most visible number — it shows up in your paycheck every two weeks. Deductibles and out-of-pocket maximums feel abstract until you actually need care.
Failing to check whether your current doctors and hospitals are in-network under the new plan year.
Why it happens: Networks can change annually, but most people assume their providers stay in the same plan because they were in it last year. The notification process is inconsistent and easy to miss.
Skipping the formulary check for prescription drugs.
Why it happens: Formulary documents can be long and difficult to navigate. People assume that if a drug was covered last year, it will be covered this year.
Missing the enrollment deadline because of procrastination or confusion about dates.
Why it happens: Enrollment windows are short and easy to lose track of amid work and personal obligations. Many employees receive a single email notification and never follow up.
Forgetting to actively elect or re-elect Flexible Spending Account (FSA) contributions.
Why it happens: FSA elections almost never carry over automatically — they require a new selection each year. Many employees forget this because the FSA funds from the previous year are still being spent down.
Not updating or verifying dependent information during enrollment.
Why it happens: Life changes happen throughout the year — a divorce, a child aging off the plan, a new spouse — but it's easy to assume the system already reflects these changes.
Enrolling in both an FSA and an HSA without understanding they can't coexist in most cases.
Why it happens: Both accounts offer pre-tax savings for medical expenses, so they seem complementary. The eligibility rules are counterintuitive and not always clearly communicated during enrollment.
49%
Employees who auto-renew without reviewing options
According to a 2023 Aflac WorkForces Report, nearly half of U.S. employees simply re-enroll in the same benefits without reviewing alternatives.
$1,500+
Average annual cost difference between plan choices
A 2022 National Bureau of Economic Research study found that employees choosing suboptimally during open enrollment overpaid by an average of $1,500 annually in total healthcare costs.
3 in 10
Workers who don't understand their health benefits
The 2023 Employee Benefit Research Institute survey found roughly 30% of covered workers said they didn't fully understand the health benefits they had selected.
14 days
Median employer open enrollment window length
According to SHRM research, the median open enrollment window for employer-sponsored plans is just two weeks — leaving little room for procrastination.
1 in 5
Enrollees surprised by network or formulary changes
A Kaiser Family Foundation survey found approximately 20% of insured adults reported unexpected costs due to provider network or drug formulary changes year over year.
Once you've reviewed the mistake list above, it's worth taking a moment to check your assumptions about what open enrollment actually requires. Many people carry beliefs about the process that simply aren't accurate — our article on open enrollment myths that cost people coverage addresses the most damaging misconceptions head-on.
The Auto-Renewal Trap: What Actually Happens When You Do Nothing
Auto-renewal deserves its own spotlight because it's the single most common source of unpleasant surprises. Here's the mechanics of it: if you don't actively make a selection during open enrollment, your employer or the Marketplace will typically re-enroll you in the same plan you had last year — or the closest available equivalent if your plan was discontinued.
This sounds harmless. But consider what can change between January 1st of one year and the next:
- Premiums: Your contribution amount may have increased, sometimes significantly, without you noticing because payroll deductions just adjust automatically.
- Formulary: The list of covered drugs your plan will pay for can change annually. A medication that was a Tier 2 drug last year might move to Tier 4 — or be removed entirely.
- Network: Hospitals, specialists, and primary care physicians can be added or dropped from your plan's network. Your longtime doctor may no longer be in-network.
- Your own health needs: Maybe you were healthy last year and a high-deductible plan made sense. This year you're managing a chronic condition. The same plan is now the wrong plan.
Plan Discontinuation Can Force Unexpected Changes
If your previous plan is discontinued, the auto-enrollment system will place you in the "closest comparable" plan — but that determination is made by the insurer, not you. The closest plan may have a different network, a higher deductible, or a formulary that excludes one of your medications. Always verify what you've been auto-enrolled into, not just whether you've been enrolled at all.
FSA Funds Don't Roll Over the Way You Think
Flexible Spending Accounts operate on a "use it or lose it" basis. While some plans allow a modest rollover (up to $640 in 2024) or a grace period, most require you to spend the balance by the plan year end or December 31st. If you over-elect in anticipation of expenses that don't materialize, you forfeit the remainder. Be conservative with FSA elections if your upcoming healthcare needs are uncertain.
The fix is simply making open enrollment an active process, not a passive one. Even if you review your options and decide to stay in the same plan, that's a valid choice — but it should be a deliberate one. Block two hours on your calendar during the enrollment window and treat it as a non-negotiable appointment.
If you want to build better habits around this process year over year, getting the most from open enrollment each year offers a practical framework for approaching it strategically, not just reactively.
Understanding Your Plan Documents Before You Commit
One of the most underused tools available to every enrollee is the Summary of Benefits and Coverage (SBC). Federal law requires every health plan to provide one, and it follows a standardized format — meaning once you know how to read one, you can compare plans side by side in a meaningful way.
Here's what to look for in the SBC before you enroll:
- Deductible: The amount you pay out of pocket before insurance starts sharing costs. Note whether the deductible applies per individual or per family, and whether it applies to all services or only certain categories.
- Out-of-pocket maximum: The absolute most you'll pay in a plan year. Once you hit this number, the plan covers 100% of covered services. This is your financial safety net — know the number.
- Copays vs. coinsurance: A copay is a flat dollar amount (e.g., $30 for a primary care visit). Coinsurance is a percentage you owe after the deductible is met (e.g., you pay 20%, plan pays 80%). Plans often use both depending on the service.
- Network type: HMO plans generally require referrals and don't cover out-of-network care except in emergencies. PPO plans offer more flexibility but typically cost more in premiums.
- Drug coverage: Look up your current prescriptions in the plan's formulary — this is a separate document you'll need to request or find on the plan's website.
If your employer offers a High-Deductible Health Plan (HDHP) paired with a Health Savings Account (HSA), that option requires some additional analysis. HDHPs carry lower premiums but higher deductibles, and the HSA — which lets you save pre-tax dollars for medical expenses — can offset the risk if you fund it strategically. Our HDHP and HSA overview walks through how these accounts work and who benefits most from this combination.
Verify Network Status Directly — Don't Assume
Online provider directories are not always current. A physician listed as in-network during enrollment may have left the network by the time you schedule an appointment. For high-stakes care — surgery, specialist treatment, or ongoing chronic disease management — call both the provider's office and the insurer directly before your first appointment to confirm network status. Get confirmation in writing whenever possible.
A Missed Enrollment Deadline Has Real Consequences
If you miss open enrollment without a qualifying life event, you will likely be uninsured or stuck in your current plan for the entire next plan year. There is no appeals process for late enrollment in most employer plans. The Marketplace also enforces strict deadlines. If you realize you've missed the window, contact your HR department or a navigator immediately — in rare cases, employer error or system issues can create exceptions, but these are not guaranteed.
Deadlines, Life Events, and What Happens If You Miss the Window
Let's be direct: if you miss your open enrollment deadline, your options are limited. Outside of open enrollment, you can only make changes to your health coverage if you experience a qualifying life event (QLE) — things like getting married, having a child, losing other coverage, or moving to a new coverage area. This triggers a Special Enrollment Period (SEP), typically a 30 to 60 day window depending on the event type and whether you're on an employer plan or a Marketplace plan.
Missing open enrollment without a qualifying event means waiting until the next open enrollment cycle — potentially 10 to 12 months away. During that time, you'd either be uninsured or need to explore limited options like COBRA (expensive) or short-term health plans (limited coverage, not ACA-compliant).
This is why procrastination is genuinely risky during this season. "I'll do it tomorrow" has left many people stuck in plans — or without plans — for an entire year.
To understand what qualifies as a life event and how the SEP process works, visit our Special Enrollment hub. And if you've ever thought "I'll just enroll when I need it," our article on why people miss their special enrollment window explains why that reasoning often fails in practice.
Here's a simple pre-enrollment checklist to keep you on track:
- ☐ Confirm your employer's or Marketplace open enrollment start and end dates
- ☐ Gather a list of all current prescriptions and check each plan's formulary
- ☐ Verify that your doctors and preferred facilities are in-network under each plan option
- ☐ Estimate your expected healthcare usage for the coming year (routine visits, planned procedures, ongoing treatments)
- ☐ Calculate total annual cost for each plan: premium × 12 + estimated out-of-pocket costs
- ☐ Review FSA and HSA contribution limits and decide on elections
- ☐ Confirm dependent eligibility and update as needed
- ☐ Submit your enrollment selections before the deadline — don't wait for the last day
A Final Word Before You Enroll
Open enrollment isn't just a benefits administration task — it's one of the most financially significant decisions you'll make each year. The plan you choose affects what you'll pay for prescriptions, whether your doctors are covered, how much a hospital stay will cost you, and how much you'll contribute to savings accounts that carry real tax advantages.
The good news is that avoiding these pitfalls doesn't require expertise. It requires time, the right questions, and the willingness to treat this process as the priority it actually is. Use the checklist above, read your SBC, check your formulary, and make an active choice rather than a default one.
If this is your first time navigating employer benefits — or your situation has changed significantly — it may also be worth a conversation with your HR department or a licensed benefits advisor. Many employers offer access to benefits counselors during open enrollment at no charge.
For a broader look at what smart enrollment habits look like over time, getting the most out of open enrollment each year is worth bookmarking for next cycle. And if you're also considering Marketplace coverage, review our guide on Marketplace enrollment mistakes before you finalize anything.
Verify Network Status Directly — Don't Assume
Online provider directories are not always current. A physician listed as in-network during enrollment may have left the network by the time you schedule an appointment. For high-stakes care — surgery, specialist treatment, or ongoing chronic disease management — call both the provider's office and the insurer directly before your first appointment to confirm network status. Get confirmation in writing whenever possible.
A Missed Enrollment Deadline Has Real Consequences
If you miss open enrollment without a qualifying life event, you will likely be uninsured or stuck in your current plan for the entire next plan year. There is no appeals process for late enrollment in most employer plans. The Marketplace also enforces strict deadlines. If you realize you've missed the window, contact your HR department or a navigator immediately — in rare cases, employer error or system issues can create exceptions, but these are not guaranteed.
All claims in this article are backed by peer-reviewed research. We follow strict editorial guidelines to ensure accuracy and reliability. Sources available on request from our editorial team.
