5 Health Insurance Mistakes Costing You

Health insurance is one of the pricier products you're likely to buy. It's also one of the most confusing.

Studies show that most Americans have a poor understanding of their health benefits and how they impact their ability to access and pay for medical care. A study out last year by researchers at Carnegie Mellon University found that among a group of people with work-based health insurance, just 14 percent were able to accurately define four basic health insurance terms: co-payment, co-insurance, premium and deductible.

Failing to understand insurance terms and your health plan's rules can lead to costly mistakes. Here are five of the most common health insurance mistakes consumers make and how to avoid them:

1. You focus on just your monthly insurance bill.

Experts say one of the most common errors people make is choosing a health plan based solely on the cost of its monthly bill, also called a premium. But your premium is not the only cost you'll face if you need medical care.

For example, most plans today require you to first meet a deductible, which may mean spending thousands of dollars before your insurer helps you pay the bills.

Once you meet that deductible, there are other out-of-pocket costs you're responsible for paying as well. Many doctor visits or lab tests, for example, require you to pay co-pays, which are fixed fees paid upfront for a doctor visit or prescription. In some cases, you may be responsible for co-insurance, a percentage of the cost of your care.

Depending on your medical needs, it may be less expensive for you in the long run to purchase a plan that costs more on a monthly basis but covers more out-of-pocket costs when you go for care.

"It's a matter of doing the math and figuring out how many visits and prescriptions you use over a year, so you can match that up to a medical plan that fits your needs," says Carrie McLean, customer service director for the private insurance exchange eHealth.

[See: Top Health Insurance Companies .]

2. You don't ask if your doctor is in-network.

Is your doctor in your health plan's network or out? The answer will have a big impact on your wallet.

"Seeing a doctor who is outside your plan's network can be very costly," says Sabrina Corlette, project director with Georgetown University's Health Policy Institute.

In addition, Corlette says, finding a doctor who participates with your plan is more challenging today. As a way of keeping costs down, most insurers are limiting the number of providers they cover. As a result, many of the new policies being sold on the private insurance market today have smaller provider networks than before the Affordable Care Act took effect.

Furthermore, a recent report by Corlette and her colleagues at Georgetown University's Health Policy Institute found that insurers employ a tactic that is common with prescription drug coverage. In some cases, insurers are placing doctors and hospitals on different "tiers." That means even those considered "in-network" with your health plan will be covered at different rates.

To avoid surprise bills, always check your doctor's network status before stepping foot in her office. And don't just rely on your insurer's provider directory -- they're notorious for containing inaccuracies.

"Call both the insurance company and the provider to confirm that the provider is, in fact, in network before going for care," Corlette says.

[Read: Socked With an Out-of-Network Medical Bill? ]

3. You don't check your plan's medication list.

It's also critical to confirm that any medications you take are included on your health plan's list of drugs (also called a formulary). You'll generally find your health plan's list of covered medications posted on its website. But beware: Those lists aren't always complete. Here again, call to confirm coverage.

Also be aware that insurers typically require you to jump through a number of hoops in order to have your prescriptions paid for. For example, you may be required to first obtain pre-authorization before filling the prescription. Also common is the requirement that you try a less expensive medication before getting the green light on a pricier name-brand alternative your doctor may have prescribed.

4. You don't know the difference between prevention and intervention.

The Affordable Care Act requires new insurance policies to cover the full cost of many preventive services with no co-payments or other charges. Annual checkups, vaccinations and cancer and other health screenings, in most cases, come with no cost to you at the time of the visit.

Often, however, the details of what's covered and what's not gets confusing, and many people get stuck with surprise bills.

"New plans are promoting preventive care at no cost, so people assume their physical won't cost them anything," McLean says. "They don't understand that if the doctor finds something and does more lab work or asks you to come back for a follow-up visit, it's now diagnostic and not preventive," she says. That means you'll be charged for the care you receive.

To avoid surprise bills, it's a good idea to be clear about the purpose of your visit when you make an appointment with your doctor, and to ask about the nature and cost of any follow-up visits.

[Read: 8 Keys to Picking the Best Individual Health Insurance Policy .]

5. You pay your bills too soon.

Once you've gone to the doctor or been to the hospital, you can expect a steady stream of bills to follow. You'll also receive a document from your insurer called an explanation of benefits, or EOB. It shows the service you got, how much your doctor charged and what portion of the bill your insurer paid.

"Don't pay anything until you get the EOB," says Karen Pollitz, senior fellow with Kaiser Family Foundation. "It tells you the service you received and what you paid. If something looks funny, don't pay it and see if you can get it fixed," she says.

If you find an error, contact the billing department at either the hospital or medical group where you received services. If the provider participates with your health plan, your insurer can also be of help.

In addition, Pollitz says, consumer assistance programs are available in most states to assist you with billing and other insurance problems. The number should be listed on your EOB statement.

[See: Infographic: How to Read Your Hospital Bill .]