You went to the emergency room, or had surgery at a hospital in your plan's network, and weeks later a bill arrived from a doctor you never chose. If you have private health insurance, federal law now protects you from many of these surprise bills. Here is what is covered, what is not, and what to do if one lands in your mailbox.

What is a surprise medical bill?

A surprise bill usually comes from an out-of-network provider you did not pick and could not avoid. Common examples include an emergency room doctor, an anesthesiologist or a radiologist at an in-network hospital. In the past, these providers could bill you for the difference between their charge and what your insurer paid. That practice is called balance billing.

What the No Surprises Act protects

Under the federal No Surprises Act, people with private insurance are protected in three main situations:

Emergency care. Out-of-network emergency room visits are covered by the protections.
Non-emergency care at in-network facilities. This generally includes out-of-network providers at in-network hospitals, hospital outpatient departments and ambulatory surgical centers.
Air ambulance services. Out-of-network air ambulance bills are also covered.

In these cases, you should only owe what you would normally pay for in-network care, such as your usual copay, coinsurance or deductible.

What is not covered

Ground ambulances are generally not covered by the federal rules, although some states have their own protections.
Short-term health plans, health care sharing ministries and fixed indemnity plans are not covered.
Dental-only and vision-only plans are generally not covered.
Medicare, Medicaid, TRICARE and VA care already have their own billing protections.

If you don't have insurance

If you are uninsured or paying for care yourself, providers usually must give you a good faith estimate of the cost before you get care. If your final bill is at least $400 higher than that estimate, you may be able to dispute it.

What to do if you get a surprise bill

Don't pay it right away. Check whether the care falls under the protections above.
Compare the bill with your Explanation of Benefits. Your insurer's statement shows what it paid and what it says you owe.
Call the provider's billing office. Ask whether the bill was processed under the No Surprises Act, and ask them to correct it if not.
Call your insurer. Ask them to reprocess the claim at in-network rates if it qualifies.
File a complaint if needed. The federal No Surprises Help Desk is available at 1-800-985-3059.

The bottom line

If a surprise bill arrives after emergency care or a procedure at an in-network hospital, you may owe far less than the amount on the page. Check your rights before you pay, and ask for the bill to be corrected.