Good Faith Estimate: What the $400 Rule Lets You Dispute

Add up everything you were billed for the day, subtract the good faith estimate, see whether the difference clears $400. That is the arithmetic nearly everyone does when they hear about the $400 rule, and it is the wrong arithmetic — it will tell you that you have a dispute when you do not, and none when you do.

The federal test runs one provider at a time. It compares what a single provider or facility billed you against what that same provider or facility wrote on its own estimate (45 CFR 149.620(b)(1)). So a $600 overrun spread across three bills — $250 from the surgery center, $200 from the anesthesiologist, $150 from pathology — clears nothing at all. A single $410 overrun on the surgery center's bill, on a day when the other two came in under their numbers, is eligible.

Everything below was read against the eCFR text of 45 CFR 149.610 and 149.620 on 29 August 2026 (title 45 current through the 26 August 2026 issue date). Both sections still carry an amendment date of 7 October 2021, the interim final rule that created them, so nothing in the regulation itself has moved in five years. The dollar figures that did move come from CMS guidance, and those are dated where they appear. Not a lawyer, not a biller.

Two totals, one provider at a time

Three defined terms carry the whole eligibility question, and they are all in 149.620(a)(2).

Substantially in excess means, with respect to total billed charges by a provider or facility, an amount that is at least $400 more than the total expected charges listed on the good faith estimate for that provider or facility. Not $400 more than the estimate as a whole. Not $400 as a percentage of anything. A flat, unindexed number that has not changed since 2022.

Total billed charges is deliberately wider on the other side of the subtraction: the total charges by that provider or facility for all primary items or services and all other items or services furnished in conjunction with them, regardless of whether they were included in the good faith estimate. The unplanned biopsy that never appeared on the estimate still counts toward the billed total being compared.

One wrinkle catches people whose provider changed at the last minute. If a co-provider listed on the estimate is swapped out, the replacement's bill is measured against the original co-provider's estimated charges (149.620(b)(2)) — unless the replacement issued an estimate of its own, in which case that new number becomes the yardstick.

The estimate in your hand probably has one name on it

Read 149.610 and the good faith estimate looks comprehensive. The convening provider — the one who takes your request and schedules the primary service — has to contact every co-provider and co-facility reasonably expected to be involved within 1 business day, ask for their numbers, and fold them into one document (149.610(b)(1)(v)). The estimate is supposed to arrive as an itemized list grouped by each provider or facility.

That is not what shows up in the envelope, and one document explains why. In FAQs about Consolidated Appropriations Act, 2021 Implementation — Good Faith Estimates for Uninsured (or Self-Pay) Individuals, Part 3, dated 2 December 2022, HHS asked its own question — will CMS enforce the co-provider requirement beginning 1 January 2023 — and answered with a flat No. It extended enforcement discretion "pending future rulemaking" for estimates that leave co-provider and co-facility charges out, on the reasoning that compliance "is likely not possible" while the industry has no agreed way for a convening provider to exchange estimate data with co-providers. Three weeks later, Part 4 (27 December 2022) wrote rules that apply "during the exercise of enforcement discretion" and will "continue to apply once the co-provider requirement" is enforced — drafted, in other words, for a wait of no stated length. Nothing published since on CMS's guidance list ends it. The discretion began 1 January 2022 and is still running.

Which lands on you as a practical problem. If the anesthesia group's charges were never on any estimate, there is no estimate of theirs to measure their bill against, and their bill is not eligible for the $400 test on its own terms.

There is a paragraph that fixes this, and it is worth using before the procedure rather than after. Under 149.610(b)(2)(iv), if you separately request an estimate from a provider or facility that would otherwise be a co-provider, that provider becomes a convening provider for that service and owes you a full estimate under (b)(1) and (c)(1). So ask each name on the schedule — the surgeon, the anesthesia group, the facility, the pathology lab — in writing, one request each. Four estimates give you four separate $400 tests. One estimate gives you one.

The trigger for a request is generous, too: convening providers and facilities "shall consider any discussion or inquiry regarding the potential costs of items or services under consideration as a request for a good faith estimate" (149.610(b)(1)(iv)). The phone call where you asked what this was going to cost was already a request.

What the paper is required to carry

Content is fixed by 149.610(c)(1), and a document missing these pieces is worth challenging before the service, not after:

• Your name and date of birth, and a plain-language description of the primary item or service.
• An itemized list grouped by each provider or facility, covering the items expected for that period of care.
• Applicable diagnosis codes, expected service codes (CPT, HCPCS, DRG or NDC), and the expected charge attached to each line.
• The name, National Provider Identifier and Tax Identification Number of every provider or facility represented, plus the state and location where the work happens.
• A list of anything that will need separate scheduling, under a disclaimer explaining that separate estimates come on request.
• One disclaimer has to tell you that you may start the dispute process if billed charges land substantially in excess of the estimate. It must also say where to find out how, and that using the process will not affect the quality of your care.
• Another has to say the estimate is not a contract and does not oblige you to use anyone named on it.

Timing sits in (b)(1)(vi). Scheduled at least 3 business days ahead, the estimate is due no later than 1 business day after scheduling; at least 10 business days ahead, within 3 business days; requested without scheduling, within 3 business days of the request. If the scope changes afterward, a new estimate is due no later than 1 business day before the service (b)(1)(vii)), and a provider substituted later than that has to accept the estimate of the one it replaced (b)(1)(viii)).

Then the line most patients never learn. The estimate is part of your medical record, and on request a convening provider or facility must hand you a copy of any estimate it issued within the last 6 years (149.610(f)(1)). If yours went missing in a move, that is the sentence to quote. Ask for it in the same letter as the line items, using wording that actually produces them: Requesting an Itemized Bill: The Exact Words to Use.

120 days, and the day that starts counting

The notice opening a dispute must be postmarked within 120 calendar days of receiving the initial bill containing the excess charge (149.620(c)(1)). The initial bill. Not the final statement, not the collection letter, not the day you gave up negotiating. Spending four months on the phone with the billing office is the most common way this route closes on its own.

The initiation notice has to contain six things (149.620(c)(2)(i)): enough information to identify the item or service, including the date it was provided and a description of it; a copy of the bill; a copy of the good faith estimate; the provider's contact details if they are not on the estimate; the state where the care was furnished; and how you want to be contacted.

CMS's Dispute a medical bill page, read 29 August 2026, points to two routes: the online portal at nsa-idr.cms.gov/billdisputes, or the paper Patient-Provider Dispute Resolution Form. The mailing details are printed on the form itself — C2C Innovative Solutions Inc., Patient-Provider Dispute Resolution, P.O. Box 45105, Jacksonville, FL 32232-5105, or fax 888-610-4092 — together with the No Surprises Help Desk number, 1-800-985-3059, and FederalPPDRQuestions@cms.hhs.gov.

The fee is $25, non-refundable, and the dispute does not start until it is paid. Cash and personal checks are refused; the mail route takes a cashier's check or money order, the online route takes a card or a payment app. The regulation names no figure at all — 149.620(g)(2) leaves the amount to be specified by the Secretary through guidance — so $25 is a number to re-check on the CMS page rather than carry over from an old article.

Two mismatches are worth knowing about before they discourage you. CMS's eligibility screener asks whether you have an estimate "that you received from your health care provider or facility three (3) days before your scheduled appointment," which is a tighter question than anything in 149.620(b). And the paper form CMS links today still carries OMB control number 1210-0169 with an expiration date of 04/30/2022 printed at the top of every page. Neither is a reason to talk yourself out of filing. Both are reasons to call the help desk and ask rather than guess.

After you file: whose turn, and for how long

HHS assigns a selected dispute resolution (SDR) entity, which notifies you and the provider that a dispute is under review (149.620(c)(3)) and then checks the file.

If the notice is incomplete or the service looks ineligible, you get an insufficiency notice and 21 calendar days to supply what is missing — extended to 35 calendar days if you asked for an accessible format and did not get one within 14 days (149.620(c)(4)(ii)). If it clears, the provider has 10 business days to submit its own package: the estimate, the billed charges, and, if it has any, documentation that the difference reflects a medically necessary item or service based on unforeseen circumstances that could not reasonably have been anticipated (149.620(f)(2)(i)). The SDR entity then has 30 business days from receiving that to decide (149.620(f)(2)(ii)).

The collections freeze in 149.620(c)(5) runs across all of it, and late fees have to stop accruing.

The three ways an SDR entity can price your bill

The determination is made item by item, not as one haggle over the total: the SDR entity must make a separate determination for each unique item or service charged (149.620(f)(3)(i)), then price each one down one of three branches (f)(3)(iii). For an item that appears on the estimate:

1. Billed at or under the expected charge — you pay the billed amount.
2. Billed above the expected charge, and the provider's explanation is not credible information that the gap reflects a medically necessary service arising from unforeseen circumstances — you pay the estimate. The rule defines credible information as information that upon critical analysis is worthy of belief and is trustworthy.
3. Billed above the estimate with credible information behind it — you pay the lesser of the billed charge or the median amount plans pay for the same or similar service by a same or similar provider in that geographic area, taken from an independent database, with the estimate acting as a floor.

For an item that never appeared on the estimate at all, the first branch is blunter: no credible information, and the amount to be paid for that new item is $0.

Then the fee comes back. Where the final amount is lower than the billed charges, the SDR entity subtracts your $25 from what you owe (149.620(f)(3)(iii)(C)). Settle privately before the decision and the provider must still reduce your bill by at least half the fee — CMS puts that at $12.50 — and report the settlement within 3 business days (149.620(g)(1)(v) and (f)(1)(i)). Paying part of the bill while you wait does not count as agreeing to that amount (149.620(f)(1)(ii)), which is the paragraph to have ready if the billing office suggests otherwise.

Binding, and narrow

The determination is binding on both sides absent fraud or misrepresentation (149.620(f)(4)). There is no level above it. The provider may still choose to charge you less, and you may still choose to pay in full, but there is no second SDR entity to ask.

It reaches nobody who used insurance. The parallel protection for insured patients — an estimate sent to your plan, which then owes you an advanced explanation of benefits — was written into the statute and set aside before it started. In FAQs Part 49, dated 20 August 2021, HHS deferred enforcement of the estimate-to-plan requirement and all three Departments deferred the advanced explanation of benefits, each pending rulemaking. The latest public step is a progress update dated 13 December 2024 describing "continued work toward AEOB rulemaking" — consumer research and data-exchange standards, no proposed rule. Five years on, the insured route is an appeal rather than a dispute: Internal Appeal vs External Review: Which Track You're On. The balance billing protections are a third, separate thing again: What the No Surprises Act Covers, and What It Leaves Out.

Nor does it reach a bill that merely seems too high. Without an estimate there is no comparison, and without a $400 gap for one provider there is no case, however large the total. The question on the table is never whether the care was needed — only whether the overrun was explained. A facility fee that was disclosed and estimated properly stays where it is, however unwelcome the second envelope: Facility Fees: Why One Visit Produced Two Bills. And in a state HHS has found to run its own qualifying process, your request gets routed there instead (149.620(h)) — the help desk can tell you whether yours is one.

None of which is a reason to skip it. A $25 filing fee against a gap that has to be at least $400 is the best-priced form in American medical billing, and the collections freeze covers the whole time the dispute is pending. So today: find the date printed on the first bill, count 120 days forward, and write that second date on the estimate itself. Then run the comparison properly — one provider, one estimate, one bill — before you call anybody.