A few years back, I ended up in urgent care with what turned out to be a kidney stone. Not the most glamorous story, but bear with me. I was in agony, got treated, and thought, “Well, at least I have insurance.” Then the bill showed up — $1,800 out of pocket. Turns out the urgent care center I walked into was out-of-network. I had no idea. I’d picked my plan during open enrollment by basically closing my eyes and clicking “Enroll” because the whole thing felt like reading a tax document in a foreign language.
That bill taught me more about health insurance in one afternoon than I’d learned in the previous decade.
Since then, I’ve gone down a deep rabbit hole — reading policies, comparing plans, talking to HR reps, even using tools like HealthSherpa, Healthcare.gov’s plan comparison tool, and apps like Zocdoc to actually verify in-network status before I walk into any appointment. And I’ve talked to a lot of people who’ve made the same mistakes I did — or worse.
So here’s what I’ve learned. These are the ten mistakes that cost people money, stress, and sometimes real health outcomes. Some of them are surprisingly easy to fix.
Mistake #1: Picking a Plan Based on the Lowest Premium Alone
This one catches almost everyone at some point. You’re looking at your options during open enrollment, and your eyes go straight to the monthly cost. The $180/month plan looks way better than the $320/month one. Math is math, right?
Not really.
The plan with the lower premium almost always has a higher deductible — sometimes $5,000 or $6,000 — which means you’re paying that full amount out of pocket before your insurance kicks in for most services. If you’re generally healthy and never use your insurance, sure, the cheap plan might work. But one ER visit, one specialist referral, one round of physical therapy, and you’ve wiped out whatever you saved on premiums.
The smarter move is to estimate your actual healthcare usage for the year — regular prescriptions, planned procedures, how often you typically see a doctor — and then run the math on total cost (premiums + expected out-of-pocket) across each plan. It takes maybe 30 minutes and can save you hundreds or thousands.
Mistake #2: Not Checking If Your Doctors Are In-Network
This is exactly what wrecked me with my urgent care visit. And it’s not just an urgent care problem.
People switch insurance plans and don’t realize their longtime primary care doctor, their kid’s pediatrician, or their therapist is now out-of-network. They show up to an appointment assuming everything is covered, and then two months later get a bill for the full cost.
Before you finalize any plan, go to the insurer’s website and actually use their provider directory to search for every doctor you see regularly. Don’t just assume they’re in-network because they were last year. Networks change. Doctors join and leave insurance networks constantly.
Also worth knowing: hospitals can be in-network while certain doctors inside that hospital — like anesthesiologists or radiologists — are out-of-network. This is unfortunately common. Always ask ahead of any planned procedure.
Mistake #3: Ignoring the Difference Between HMO, PPO, EPO, and HDHP
These acronyms feel meaningless until they cost you money.
Here’s the short version in plain English:
- HMO (Health Maintenance Organization): You need a primary care doctor who refers you to specialists. Going outside the network? Usually not covered at all.
- PPO (Preferred Provider Organization): More flexibility. You can see out-of-network doctors, though it costs more. No referrals needed for specialists.
- EPO (Exclusive Provider Organization): Like a PPO but without out-of-network coverage (except emergencies). No referrals needed, but you’re locked into the network.
- HDHP (High Deductible Health Plan): High deductible, lower premiums, and eligible for a Health Savings Account (HSA). Good if you’re healthy and want to build tax-advantaged savings for future medical costs.
People sign up for an HMO without realizing they need a referral to see a dermatologist, then get frustrated when their claim gets denied because they just went directly. Knowing the plan type upfront saves a lot of headaches.
Mistake #4: Not Using a Health Savings Account (HSA) When You’re Eligible
If you’re on a High Deductible Health Plan, you’re eligible for an HSA. And if you’re not contributing to one, you’re genuinely leaving money on the table.
Here’s why HSAs are worth understanding: contributions are tax-deductible, the money grows tax-free, and withdrawals for qualified medical expenses are also tax-free. It’s the only triple-tax-advantaged account in the US tax code. And unlike FSAs (Flexible Spending Accounts), the money doesn’t expire at the end of the year — it rolls over forever.
Some employers even contribute to your HSA. If yours does and you’re not taking advantage of that, it’s like turning down a pay raise.
You can open and manage an HSA through banks and platforms like Fidelity, Lively, or HealthEquity. Fidelity’s HSA in particular has zero fees and lets you invest the balance once it hits a certain threshold.
Mistake #5: Skipping Preventive Care Because You “Feel Fine”
Most health insurance plans — especially under ACA-compliant policies — cover preventive care at 100% with no cost-sharing. That means annual physicals, certain cancer screenings, vaccinations, and other preventive services are free.
People skip these because they feel healthy, or they don’t want to take time off work, or they forget to schedule. And then something that could’ve been caught early turns into something expensive and serious.
I have a friend who skipped his annual checkup three years running because he felt fine. When he finally went, his blood pressure was dangerously high — had been for who knows how long. Now he’s on medication that he’ll likely take for life. Could earlier detection have changed that? Maybe not, but the point is: preventive care is free. Use it.
Set a calendar reminder each year. Apps like Zocdoc make it easy to find in-network primary care doctors and book an annual exam without waiting on hold.
Mistake #6: Missing Open Enrollment Deadlines
Open enrollment for employer plans is typically a two-to-four week window once a year. For ACA marketplace plans, it usually runs November 1 through January 15. Miss it, and you’re stuck with whatever you have (or no insurance at all) until the next year — unless you qualify for a Special Enrollment Period.
Special Enrollment Periods are triggered by qualifying life events: getting married, having a baby, losing other coverage, moving to a new state. But they’re time-sensitive — you usually have 60 days from the event.
People miss these windows all the time just because they didn’t mark the dates. Set reminders in your phone. If you get your insurance through work, your HR team will announce open enrollment — actually read those emails.
Mistake #7: Not Understanding Your Explanation of Benefits (EOB)
After any medical visit, you’ll eventually get an Explanation of Benefits from your insurer. It’s not a bill, but it shows you exactly what your insurance paid, what the provider billed, and what you owe.
Most people throw these away without reading them. That’s a mistake.
EOBs are how you catch billing errors. And medical billing errors are shockingly common. Studies suggest a significant portion of hospital bills contain errors — double billing, charges for services not received, incorrect codes. If you never read your EOB and just pay the bill, you’ll never catch it.
Make a habit of comparing your EOB to any bill you receive from a provider. If the numbers don’t match, call the billing department. If you suspect an error, you can also call your insurer directly.
Mistake #8: Assuming ER and Urgent Care Are the Same Thing
Emergency rooms and urgent care centers are not interchangeable from an insurance perspective, and walking into the wrong one is an expensive mistake.
Most insurers consider ER visits “emergency care” and apply different — usually higher — cost-sharing unless it’s a true emergency. Urgent care centers, when in-network, typically have a lower copay and are better suited for things like sinus infections, minor injuries, or anything that’s not immediately life-threatening.
Some people default to the ER because it feels “safer” or because they don’t know there’s an urgent care nearby. Before you need it, find the in-network urgent care options closest to your home and workplace. Save them in your phone. Apps like Solv let you find urgent care centers, check wait times, and even book same-day appointments.
That said, if something feels like it could be a real emergency — chest pain, difficulty breathing, severe trauma — go to the ER. Insurance headaches are solvable. Your life isn’t replaceable.
Mistake #9: Not Appealing Denied Claims
Getting a claim denied feels final. It’s not.
Insurers deny claims for all kinds of reasons — some legitimate, some administrative errors, some debatable. You have the legal right to appeal every denial, and a surprising number of appeals are successful, especially when a doctor provides supporting documentation.
Here’s the general process:
- Read the denial letter carefully — it must explain the reason for denial.
- Ask your doctor’s office to write a letter of medical necessity if the denial was clinical.
- Submit your internal appeal to the insurer in writing, within the deadline (usually 180 days from the denial).
- If that’s denied, you typically have the right to an external review by an independent third party.
Insurance companies know that most people won’t bother to appeal. Don’t be that person. Even if it takes a few hours of paperwork, it can save you hundreds or thousands of dollars.
Mistake #10: Not Reviewing Your Coverage Every Year
Life changes. Your insurance coverage should keep up.
A plan that was perfect when you were 28, healthy, and single might be completely wrong at 35 with a spouse, a toddler, and a recurring back issue. Or maybe you got healthier and are now over-insured and paying for coverage you don’t need.
Every open enrollment, actually sit down and reassess. Did your income change? Do you have a new provider you want to make sure is in-network? Are you planning any procedures or pregnancies in the upcoming year? Is there a new drug you’re taking that might be covered differently on a different plan?
Take an hour. Compare your current plan against the alternatives. Healthcare.gov’s plan comparison tool is genuinely useful for marketplace plans. If you have employer coverage, don’t assume the same plan is the best option — sometimes a new tier gets added that fits your situation better.
One More Thing Worth Saying
Health insurance is complicated by design, which is deeply frustrating. But the people who get the most out of their coverage aren’t always the healthiest — they’re the ones who took the time to understand what they signed up for.
You don’t need to become an insurance expert. You just need to avoid the common traps: pick the right plan type for your situation, make sure your doctors are in-network, use your preventive care benefits, contribute to your HSA if you can, and actually read the paperwork when claims get processed.
The kidney stone bill I mentioned at the beginning? I fought it. I called the insurance company, explained that I had no way of knowing the center was out-of-network in an urgent situation, and escalated the complaint. I didn’t get it completely reversed, but I got it reduced to $600. Still not fun, but a lot better than $1,800.
You have more leverage than you think. Use it.
Have a health insurance horror story or a tip that saved you money? Drop it in the comments — real experiences help more people than any list ever could.
