For health insurance consumers, getting the most out of your benefits means considering a wide range of factors.. Greater numbers of plans, provider networks that shift without notice and increasing deductibles all mean more preparation and homework. But even when you think you’ve done everything right, you can be caught with an unexpected medical bill.

Genevieve Schaefer, 26, of Fort Collins, Colo., thought she was prepared. She shopped online in her state’s marketplace for a plan that would allow her to keep her doctor and get an intrauterine device (IUD) for free— the only medical procedure she anticipated for 2014. When the provider search on the site wasn’t working, she called the help line and called her doctor, double-checking that the plan she was after included her physician in its network. All seemed well. She purchased an Exclusive Provider Organization, or EPO, plan through Colorado HealthOP and scheduled her procedure for March.

READ MORE: EPO vs. PPO: Which Is Better For You?

“I received nothing from my doctor’s office and nothing from the insurance company stating I would owe anything, which is what I expected,” Schaefer says, adding that she provided her doctor’s office with her new policy information and had a total of three appointments: her annual physical in February, the IUD procedure in March and a follow-up in April. It wasn’t until December that she received a bill— for $902.

"I was charged for all three appointments, including the IUD and procedure, as services that weren’t covered under my plan due to my doctor being out-of-network,” she says.

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Changing networks affects many patients

Insurance networks are groups of medical providers who contract with insurance companies to provide care at a lower cost. In the past several years, these networks have increasingly “narrowed,” meaning patients often must make do with fewer options and find a new doctor when theirs isn’t included. Unfortunately these networks change often, and insurer websites and federal and state marketplaces don't always keep up.

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The federal government has taken note: The Affordable Care Act has mandated that insurers publish an up-to-date, accurate and complete provider directory. Now, starting next year, those directories must be updated monthly under requirements from the Centers for Medicare and Medicaid Services.

Had this come sooner, it might have helped Schaefer, who says she was told there wasn’t anything the insurance company could do.

Preventing out-of-network charges

When it comes to finding providers in your network, looking on either your insurer’s or doctor’s website won’t suffice. Instead, you’ll need to pick up the phone and a pen, making a note of who you talk to and when in case discrepancies arise down the road.

● Contact any physicians you’re hoping to see and ask whether they’re part of your network. Asking whether they “accept” your insurance is not enough, as even out-of-network doctors might “accept” your plan.
● Call your insurer with the name and address of your provider. If you can get it, obtain your provider’s tax ID as well. The address and tax ID will differentiate your doctor from others with similar names or different clinic locations. Ask for confirmation of network status via email, so you have something in writing.
● Reconfirm your doctor’s in-network status with your insurance company the day before any appointments, as that status can easily change without notice.

For planned operations or hospital stays, the hospital’s scheduling or admissions office is the best place to call. The office will know which surgeons, anesthesiologists, labs and other providers might bill separately during your stay, and might even be helpful in determining any network conflicts.

Dealing with out-of-network bills

If you find yourself stuck with an out-of-network bill despite your best efforts, don’t accept the balance due at face value. Negotiate. Schafer was initially offered a 20 percent discount by her doctor’s office but successfully negotiated everything away but the price of the IUD itself, which was $525.

READ MORE: How to Get Started on Medical Bill Negotiations

Doctor’s offices, and even collection departments if it goes that far, are often able to negotiate, and asking them to eliminate fees and late charges is a good place to start. Once you get the balance down, ask for the agreed-upon amount in writing and then work on establishing payment arrangements if you can’t pay off your balance in full.

Patients carry a considerable burden when it comes to preventing surprise medical bills. With the health care system in a seemingly constant state of flux, it pays to do your homework and err on the side of being too cautious.