dollarsPeter Drier isn’t the only victim by an nefarious insurance trap. The New York Times reports that Mr. Drier got a bill for $117,000 from a surgeon that he’d never met. It turns out, this surgeon was out of his insurer’s network and thus they wouldn’t cover most of the bill. A Wisconsin woman was snared by a worse trap: she incurred a $254,000 bill after being taken to the wrong hospital by an ambulence. Had it taken her to a hospital a few blocks away, her insurer would have covered the entire cost. Instead, it only offered to pay $156,000 of the bill leaving her with almost $100,000 in unpaid medical costs. In the industry, it’s called “balance billing” because medical providers are pursuing the “balance” of what wasn’t covered by the insurers directly from patients. And, yes, it is outrageous.

Increasingly, patients are complaining that after they undergo treatment and/or surgery, especially in emergencies, they are hit with costs they’d never imagined or expected. What is happening is that doctors and hospitals belonging to an insurer’s network use out-of-network specialists, consultants, assistants and other hospital employees without your permission. The insurer then covers only a small portion—or none—of the out-of-network provider’s fee, and you are billed for the rest. Unlike in-network providers who agree to discounted rates negotiated with the insurer, out-of-­network providers charge their full fees, which may be 20 to 40 times higher.

For Medicare customers, you are protected, because Medicare doesn’t allow providers who accept Medicare payments to bill patients beyond what Medicare covers. But if you have a private health insurer, here’s how to protect yourself against out-of-network hospital or doctor bills:

First, when you sign hospital consent forms, make sure there’s no language that allows a doctor to do this without your express permission.

Second, take some time to scope out what hospitals are in your network in case of an emergency. Then ask what percentage of ER doctors and other personnel there are out of network.

Third, if you are having a planned procedure, be sure to ask your doctor well in advance who else might be involved in your case, and insist that everyone be in-network unless there is an overriding need for someone out of network to take part. Seek to work out terms in advance with out-of-network providers.

Fourth, check out your state laws. Colorado and Maryland have passed more serious protections, which force at least some insurers to pay surprise out-of-network charges; in these cases, patients are simply billed as if they were in-network. New York has passed similar legislation, but the arbitration process is screwy. Other states have similar balance billing prohibitions.

As more and more insurers are reducing the size of their networks as a way to reduce costs, we can expect to see increasing numbers of out-of-network balance billing incidents. Being proactive on this may save you thousands of dollars.