Dispute a bill that is $400 or more over your Good Faith Estimate

Who can use the dispute process

CMS lists these conditions on its dispute page:

• When you got care, you did not have or did not use health insurance to pay for it, and you told the provider beforehand that you would not use insurance.
• The care was on or after January 1, 2022.
• You had a Good Faith Estimate from the provider or facility.
• Your initial bill is within the 120-day window (see the deadline below).
• One of your providers or facilities charged at least $400 more than its estimate.

The $400 test is applied provider by provider. The regulation compares the total billed by a particular provider or facility with the total expected charges for that same provider or facility on the estimate (45 CFR 149.620(a)(2)(ii) and (b)(1)), so compare each bill with that provider's line on the estimate, not with the estimate's grand total.

The deadline: 120 calendar days

The regulation requires the notice starting the dispute to be postmarked within 120 calendar days of receiving the initial bill that contains the charge (45 CFR 149.620(c)(1)). CMS's consumer page describes it as an initial bill dated within the last 120 calendar days. Counting from the date printed on the bill gives the earlier of the two dates, so it is the safer one to work to.

Example: initial bill dated

September 1, 2026

120 calendar days later

December 30, 2026

What it costs

A $25 administrative fee, which CMS says is non-refundable and must be paid before the dispute starts. Online you can pay by credit card, PayPal or Venmo; by mail, by money order or cashier's check (not cash or a personal check). If the dispute is decided in your favor, the $25 is deducted from the amount you owe the provider. The regulation leaves the amount to HHS guidance, so check the CMS page for the current figure before you file.

How to file

• Online through the CMS portal at nsa-idr.cms.gov/billdisputes, which asks for your email address and sends a one-time PIN.
• By mail or fax, using the dispute initiation form (PDF).
• Have ready a copy of your Good Faith Estimate, a copy of the bill and the provider's contact details. Do not send originals.
• Questions: the No Surprises Help Desk, 1-800-985-3059.

While the dispute is open

Under 45 CFR 149.620(c)(5), the provider or facility must not move the disputed bill into collection or threaten to do so. If the bill has already moved into collection, the provider or facility should cease collection efforts. It must also suspend the accrual of late fees on the unpaid amount. CMS's page adds that the provider cannot take action against you because you are disputing the bill.

How it ends

CMS says your costs will not increase because you disputed. The reviewer may find the charges were appropriate (for example, for care your doctor could not reasonably have anticipated) and leave the bill as it is, or may find the provider should have been able to tell you about those costs in advance, or that the unplanned items were not medically necessary; in those cases the provider must reduce the bill.

You and the provider can still settle before the reviewer decides. If you do, CMS says the provider must reduce your bill by at least $12.50, half the fee, and tell the reviewer you have settled.

If you do not qualify

If you did not use insurance but never received an estimate, CMS lets you submit a complaint through the No Surprises Help Desk. If you used insurance, this process is not open to you; CMS points insured patients to its complaint process for surprise out-of-network bills and to their plan's appeal process for denied claims.

Where a FairBillCheck report fits

When you tell the checkout form you paid without insurance and had an estimate, the report runs these tests on your own numbers, prints the date to file by, and lists what to gather. The Medicare comparison and the letter to the billing office work whether or not you dispute. The report describes the federal process; it is not legal advice about your situation.