If the need to go the emergency room arises, your first instinct is likely to be a 911 call. In an emergency, getting the right care fast should be the focus. “If you’re having a heart attack, you’re not going to ask if the doctor takes your insurance,” says Karen Pollitz, a senior fellow at the Kaiser Family Foundation.

But that ER visit may have a big price tag. A Kaiser-New York Times survey of insured and uninsured people who had trouble paying medical bills found that ER bills accounted for the largest portion of what they owed.

Going to a hospital that takes your insurance may not protect you from getting billed. About two-thirds of ER doctors are independent contractors who might not be in your insurance plan. Any out-of-network doctor (or lab) may bill you for whatever your insurance doesn’t cover, a practice called balance billing.

If the ambulance company that transports you doesn’t take your insurance, your cost could be more than $2,200, depending on such factors as where you live and the level of care you receive before you get to the hospital. (A breathing tube, for example, might bump up the price.) You can’t completely protect yourself from ER billing problems and you never want to put cost concerns ahead of emergency care. But these strategies may help:

Be prepared

Ask your insurer for documentation on what the plan will and won’t cover if you need emergency care. (The insurer’s website or handbook may not be up-to-date.) Your insurer can also tell you which area hospitals take your insurance. You can then ask the billing department at your hospital of choice whether its ER doctors participate in your insurance plan.

And because most insurers cover medically necessary ambulance rides, know how your plan defines “medically necessary”: it could mean you are unconscious, bleeding heavily or in severe pain.

Going to the ER

When you call 911, a dispatcher will send the closest available ambulance, so you may not know whether it will be in your insurance network. And although you can request a particular hospital, it’s the ambulance personnel’s call — and usually they will choose the closest facility that’s properly equipped to treat you.

Under the Affordable Care Act, if you need emergency care, your copay or coinsurance cannot be higher than your in-network rate, even at out-of-network hospitals. But the law doesn’t prevent out-of-network providers from billing you for the remainder after you’ve received care.

At the hospital, you (or the family member or friend who is with you) will fill out admission forms. This is the time, if possible, to request an in-network health-care provider. At discharge, you or your companion should ask for all paperwork, including an itemized list of charges.

When you get billed

You’ll probably get separate bills from each out-of-network provider involved in your ER care. Pay nothing until you get explanation of benefits (EOB) statements from your insurer; they tell you what the plan has covered and what your portion may be. Compare bills and EOBs to make sure you received the services noted, and have your insurer confirm that providers who sent bills are not in your plan.

Then work on getting bills covered. Ask your insurer whether it will do so. You can also ask the providers who billed you to settle for what insurance has already paid them. “Some doctors will negotiate with you,” says Pat Palmer, founder and chief executive of Medical Billing Advocates of America, in Roanoke, Va. Your insurer may also negotiate on your behalf.

If the insurer and providers won’t budge, file an appeal with your insurance company. To bolster your case, ask your primary-care doctor or specialist for a letter noting that your ER treatment was medically necessary. The Patient Advocate Foundation (patientadvocate.org) offers guidance at no charge. Professional claims consultants work for a fee or a percentage of the sum reimbursed. You can find help via the National Association of Healthcare Advocacy Consultants (nahac.memberlodge.com) or the Alliance of Claims Assistance Professionals (claims.org).

At least 25 states are working toward or already have some protections against surprise medical bills. For example, in New York those bills now can go through independent dispute resolution if the health plan and provider disagree on a payment. To learn more, go to Consumers Union.org/surprise-medical-bills and click on “Get Help With a Bill.”

Copyright 2016. Consumers Union of United States Inc.

For further guidance, go to www.ConsumerReports.org/Health, where more detailed information, including CR’s ratings of prescription drugs, treatments, hospitals and healthy-living products, is available to subscribers.