CMS cut the price of federal arbitration 87% for the side that wins 85%.

The Centers for Medicare & Medicaid Services announced the change on 28 May 2026 as cost control. The press release is headed “Federal Rule Takes Aim at Saving Taxpayer Dollars,” CMS Administrator Dr. Mehmet Oz is quoted saying “we are cutting fees, improving transparency, and restoring order to a system that was overwhelmed,” and HHS Secretary Robert F. Kennedy, Jr. adds that “Americans should never be blindsided by unexpected medical bills.” Every trade outlet wrote it up as a fee cut. A fee cut is not what it is.

The rule is 91 FR 33900, “Federal Independent Dispute Resolution Operations,” published 4 June 2026 by four agencies at once — Treasury, Labor, HHS and the Office of Personnel Management, dockets TD 10049 and CMS-9897-F, effective 3 August 2026. The fee provision ran ahead of the rest of it. CMS’s own implementation timeline, issued 7 August 2026, puts it plainly: for disputes initiated “on or after June 11, 2026,” the administrative fee is “$15 per party per dispute, regardless of the amount in dispute.” For disputes initiated from 22 January 2024 through 10 June 2026 it was $115. That is an 86.96% cut to the only non-refundable cost in the process.

Everything turns on the word non-refundable, and the place to read it is 45 CFR 149.510(d) rather than the press release. Paragraph (d)(2)(i) makes the administrative fee “a non-refundable administrative fee due to the Secretary,” payable by each party. Paragraph (d)(1)(i) makes each party pay the certified IDR entity’s own fee by the time it submits its offer. Then (d)(1)(iii) does the thing nobody quotes: after a payment determination the entity keeps the fee paid by the non-prevailing party and returns the prevailing party’s fee “within 30 business days.” Lose and you pay the arbitrator. Win and the arbitration cost you $15.

So the price of the arbitrator is a probability, not an invoice, and CMS publishes the inputs for both halves of it. The Court of certified entities is a list: as last updated 31 August 2026 there are 17 certified IDR entities, each with its 2026 fees printed to the dollar. Medical Evaluators of Texas charges $425 for a single determination and $700 for a batch; EdiPhy Advisors charges $800 and $1,150; Maximus Federal Services $495 and $750; Acentra $650 and $850; C2C Innovative Solutions $485 and $685. The median of the seventeen is $525 single and $770 batched. You do not get to pick — the parties agree or the Departments assign — so the honest planning number is the median.

The other half is the win rate, and CMS reports it twice a year. For July through December 2025: 1,372,563 disputes initiated, 1,449,900 closed, 1,145,039 payment determinations, and “providers, facilities, or air ambulance providers prevailed in approximately 85 percent.” The prevailing offer exceeded the plan’s qualifying payment amount in about 87% of determinations. Add the first half and 2,559,375 disputes were initiated in calendar 2025 alone, against about 5.1 million since the portal opened on 15 April 2022.

Now put the two together, which is arithmetic the rule does not do for you. Expected cost of one single determination after 11 June 2026: $15 plus a 15% chance of owing the median $525, so $93.75. Before 11 June it was $193.75. Divide each by the 85% win rate and you get the smallest underpayment at which arbitrating breaks even: $227.94 then, $110.29 now, a 51.61% drop in the floor without a single word changing about who wins or what they win.

What lives in the band between those two numbers is the non-consensus part. The Congressional Research Service published R48851 on 10 February 2026, reading CMS’s own public use files for 82,119 emergency disputes across 14 states: median prevailing offer $627, median qualifying payment amount $226, and a median prevailing offer running 312% of the median in-network rate. Broken out by code, CPT 99283 — the mid-acuity emergency visit, 11,804 disputes, 14.37% of the sample — carried a median QPA of $157 against a median prevailing offer of $310. That is a $153 gap. At $115 it was worth −$63.70 to fight. At $15 it is worth +$36.30. The United States flipped the sign on the median mid-acuity emergency visit on 11 June 2026.

Batching is where it stops being a rounding error. The fee is $15 per party per dispute, not per claim, and a batched dispute today carries up to 25 line items at a median entity fee of $770. Expected cost $130.50, or $5.22 a line, break-even $6.14 a line against a median gap of $401. On 1 November 2026 — fifteen days from now — the cap doubles. The Departments’ guidance of 6 October 2026 states that “a batched dispute cannot include more than 50 line items,” applying to disputes whose open negotiation periods begin on or after that date. Fifty items at a median $770 plus a median $120 tier is $148.50, or $2.97 a line.

And the last move is the one that is not arbitration at all. The Departments’ own fact sheet complains that open negotiation “is not being meaningfully used” — the 30-business-day window under 45 CFR 149.510(b) in which a plan can simply pay rather than arbitrate. For two and a half years the reason was arithmetic: on a $150 underpayment, a $115 ticket made the threat to arbitrate a bluff, and the plans could read the schedule as well as anyone. At $15 the threat is cheaper than the postage, which is why the concentrated incumbents matter less than they look. HaloMD, the largest filer, ran 22% of all disputes in the second quarter of 2025 with a median prevailing offer at 835% of QPA; TeamHealth and SCP Health follow; together the top three are about 38% of a 1.37-million-dispute half-year. They built that on claims that cleared the old floor. The band underneath it has been empty on purpose, and the purpose was repriced four months ago.