How to Dispute a Surprise Medical Bill

The hospital was in network, but a bill arrived from a doctor, an anesthesiology group, or a lab that was never chosen and never mentioned. The paperwork looks final and the due date is printed on it. The Centers for Medicare and Medicaid Services runs a federal process for exactly that situation, and it starts with documents rather than a payment.

Ask the billing department for an itemized bill

The CMS guide on checking a medical bill for errors says to request a detailed list of the cost of each item or service from the provider's billing department, ask the provider for a copy of the records to compare against that list, and check for the same service billed twice, which the page notes is common when more than one provider was involved. It also says some providers charge a records fee, so ask about that first.

Compare the bill against the explanation of benefits

Ask the plan for the explanation of benefits covering the visit. The CMS page on reading an explanation of benefits describes the fields to line up: provider charges, allowed charges, the amount paid by the insurer, and the patient balance. The page states that the bill should not be higher than the patient balance, and to talk to the provider if it is.

Check which No Surprises Act protections CMS says apply

The CMS page on rights when using insurance describes the law, effective January 1, 2022, as covering emergency room visits, non-emergency care tied to a visit to an in-network hospital, hospital outpatient department, or ambulatory surgical center, and air ambulance services. It lists ground ambulance services as generally outside those protections, and says a signed notice and consent form gives up the protections, though it names anesthesiology, pathology, radiology, neonatology, assistant surgeons, hospitalists, and intensivists as roles not permitted to ask for one.

Use the dispute process if no insurance was used

For people who did not have or did not use insurance, the CMS page on good faith estimates says a written estimate is due when care is scheduled at least 3 business days ahead or on request. The patient-provider dispute resolution page states the threshold as a charge at least $400 above that provider's estimate, a filing window of 120 calendar days from the initial bill, and a $25 administrative fee. It also says that while a dispute is open the provider cannot move the bill into collections or collect late fees, which is why that page is worth reading before any amount is paid. Those figures are as of September 2026.

File a complaint with the No Surprises Help Desk

CMS takes reports through its complaint form and by phone at the No Surprises Help Desk on 1-800-985-3059. The submit a complaint page lists what to upload: the bill, the insurance card, the explanation of benefits, any good faith estimate, any signed notice and consent form, and correspondence with the provider.

For state rules on balance billing. CMS maintains a state-by-state Consumer Assistance Program map that points to a state program or, where none exists, to the state department of insurance.

Sources. Check a bill for errors, rights when using insurance, dispute a medical bill, submit a complaint.