The No Surprises Act and surprise medical bills, explained

A "surprise" medical bill used to mean exactly what it sounds like: you went to an in-network hospital, and weeks later got a bill from an anesthesiologist or radiologist you never chose, who wasn't in your plan's network at all — for the full difference between what your insurer paid and what that provider wanted to charge. A federal law closed most of that gap starting in 2022. It didn't close all of it, and the money fight it created between insurers and providers is still working its way through federal court — neither of which changes the specific bill sitting in your mailbox.

What actually counts as balance billing, and why it was legal before

"Balance billing" is a provider billing a patient for the gap between their full charge and whatever the patient's insurance actually paid — a gap that exists precisely because the provider was out-of-network and so wasn't bound by any negotiated, in-network rate. Before 2022, a patient could do everything right — choose an in-network hospital, an in-network surgeon — and still get hit with this bill from a specialist the hospital assigned who happened not to be in-network, with no real opportunity to choose otherwise in the moment. The No Surprises Act, part of the Consolidated Appropriations Act, 2021 (Pub. L. No. 116-260, enacted December 27, 2020), made this specific pattern illegal for the situations described below, effective for care received on or after January 1, 2022.

The three situations it actually covers

Emergency care, regardless of network. An out-of-network emergency room, or an out-of-network provider treating you in one, can't bill you more than your plan's in-network cost-sharing amount — copay, coinsurance, deductible — and can't balance-bill you for the difference. This protection continues through post-stabilization care until you can be safely transferred to an in-network facility.
An out-of-network provider at an in-network facility. If you have a scheduled procedure at an in-network hospital or outpatient facility and the hospital brings in an out-of-network anesthesiologist, radiologist, pathologist, assistant surgeon, or similar "ancillary" provider without your meaningful choice in the matter, the same cost-sharing limit and balance-billing ban applies.
Air ambulance transport. Both emergency and non-emergency air ambulance rides from an out-of-network provider get the same protection — no balance bill for the gap.

The one big gap: ground ambulances

Congress deliberately left ground ambulance transport out of the No Surprises Act, citing the mix of private, municipal, and county-run services and a lack of national cost data to set a fair benchmark rate. The practical result: a ground ambulance ride from an out-of-network provider can still generate a full balance bill under federal law, and by some published estimates roughly half of ground-ambulance transports nationally involve an out-of-network provider. About two dozen states have passed their own ground-ambulance balance-billing protections since, but those only apply to a fully-insured state-regulated health plan — not to a self-funded employer plan, which covers a large share of Americans with job-based coverage and falls outside state insurance regulation entirely. Check your specific plan type and state before assuming an ambulance bill is protected either way.

If you're uninsured or paying cash: the Good Faith Estimate

Separately from the balance-billing rules above, the law requires every provider and facility to give an uninsured or self-pay patient a written Good Faith Estimate of expected charges before a scheduled service — generally within one business day if the service is scheduled at least three business days out, or three business days if it's scheduled ten or more days out, and on request even without a scheduled date. If your actual bill from that provider or facility ends up $400 or more above the estimate, you can challenge it through the federal Patient-Provider Dispute Resolution process: a request filed with HHS within 120 days of the bill, a modest administrative fee, and an independent third party who decides what you actually have to pay. The provider can't send your account to collections while that dispute is pending.

Who actually fights over the money — and why it doesn't change your bill

When an insurer and an out-of-network provider can't agree on payment for a bill covered by the law, the dispute goes to a federal independent dispute resolution (IDR) process — a "baseball-style" arbitration where each side submits a proposed payment and an arbitrator picks one. That process has been contentious since it started: the Texas Medical Association sued the federal government multiple times over rules that told arbitrators to weigh the insurer's own calculated "qualifying payment amount" heavily, arguing the rules favored insurers over the law's actual text. Most recently, the Fifth Circuit, sitting en banc, ruled against the government on August 11, 2026 (No. 23-40605), holding regulators had let insurers understate that benchmark using uncontracted "ghost rates" and by excluding certain bonus payments — a decision that will likely push IDR payments toward providers going forward. None of this back-and-forth changes your own exposure as a patient: the balance-billing ban and cost-sharing limits described above apply regardless of how the IDR dispute between your insurer and your provider is ultimately resolved.

What to actually do with a bill that looks like this

If you believe a bill violates the law, you can file a complaint with the federal No Surprises Help Desk at 1-800-985-3059 or through CMS's online complaint portal; CMS reviews it and refers it to the correct federal or state enforcement agency. The law sets a nationwide floor — a state can and sometimes does go further (for instance, with its own ground-ambulance protection), so it's worth checking whether your state has additional protections layered on top, not just the federal minimum described here.

This is not medical or legal advice for a specific bill. Whether a particular charge is actually covered by the No Surprises Act depends on the exact service, provider, facility network status, and your specific plan — details this page can't evaluate for you. Keep every bill, explanation of benefits, and Good Faith Estimate you receive, and consider a patient-advocacy organization or a consumer-law attorney if a dispute doesn't resolve through the Help Desk.