Who Is Actually on the Other Side of a Federal Dispute
CMS publishes the parties that appear most often in federal IDR — and, for each one, how its disputes break down by type of health plan. That breakdown is not trivia. Whether the plan behind your claim is a self-funded employer plan decides whether a state process can reach it at all, and filing into the wrong process is how claims die on eligibility rather than on the merits.
Plans and Representatives Most Often Disputed
| Non-initiating party or representative | Disputes, H2 2025 | Self-funded plans | Fully insured plans | No issuer response |
|---|---|---|---|---|
| UnitedHealthcare | 338,429 | 63% | 24% | 4,308 |
| BCBS Texas | 237,947 | 71% | 12% | 7,598 |
| Aetna | 185,954 | 75% | 6% | 1,680 |
| Claritev (fka Multiplan) | 144,697 | 87% | 10% | 1,452 |
| Anthem | 112,804 | 56% | 5% | 3,731 |
| ClearHealth Strategies | 95,628 | 85% | 1% | 1,215 |
| Cigna | 44,931 | 80% | 13% | 717 |
| BCBS Arizona | 22,932 | 86% | 2% | 109 |
| Centene | 19,197 | 16% | 7% | 2,540 |
| BCBS Florida | 7,849 | 1% | 45% | 4,161 |
| BCBS Illinois | 6,471 | 67% | 7% | 22 |
Source: CMS, Federal IDR Supplemental Tables, Q3 and Q4 2025, Table 9. “Non-initiating party” is CMS's own term for the party a dispute is brought against — it carries no implication about conduct, and the counts reflect volume of disputes rather than any finding. Percentages are that party's share of its own disputes by plan type; rows do not sum to 100% because individual, FEHB, government and church plans are omitted from the columns shown.
Self-Funded or Fully Insured Decides Your Route
A fully insured plan is one an insurance company sells and bears the risk on. A self-funded plan is one an employer pays claims out of its own money, usually hiring a carrier only to administer it. The name on the card can be identical in both cases — which is exactly why this trips people up.
It matters because ERISA preempts state insurance regulation of self-funded employer plans. A state surprise-billing law, however good, generally cannot reach them. So for a self-funded plan the federal IDR process is the route, even in a state that runs its own arbitration system.
The scale of this is visible in the table above. UnitedHealthcare was the most frequently disputed party in the second half of 2025 with 338,429 disputes, and 63% of them involved self-funded or partly self-funded plans. Across all disputes over out-of-network items and services in the fourth quarter of 2025, CMS recorded 482,144 of 707,501 initiations against self-funded or partly self-funded plans — 68%.
Where to find it
- The plan document or summary plan description states it directly — look for a stop-loss or self-insurance reference.
- An employer plan administered by a carrier but paid by the employer is self-funded, whatever the card says.
- If the answer is genuinely unclear, the federal route is usually the safer filing — but the deadline runs either way, so the question needs answering early rather than accurately-but-late.
The last column of the table is worth a second look as well. “No issuer response” counts disputes where the plan type was never established because the issuer did not respond. 27,533 disputes among these parties alone fell into that category in the second half of 2025.
Most Disputed Parties in Air Ambulance Cases
| Non-initiating party or representative | Disputes, Q4 2025 | Self-funded plans | Fully insured plans |
|---|---|---|---|
| Centene | 2,156 | 0% | 0% |
| BCBS Texas | 1,274 | 58% | 24% |
| Claritev (fka Multiplan) | 1,224 | 83% | 12% |
| Kaiser Permanente | 726 | 0% | 92% |
| Aetna | 714 | 62% | 9% |
| Anthem | 663 | 33% | 14% |
| UnitedHealthcare | 566 | 45% | 49% |
| ClearHealth Strategies | 484 | 80% | 1% |
| Cigna | 468 | 85% | 11% |
| Molina | 282 | 0% | 0% |
Source: CMS Table 11, Q4 2025. Shown for a single quarter because the composition of this top-ten list changes between quarters, so adding quarters would understate any party that appears in only one of them. The mix here differs sharply from other services — individual market and fully insured plans carry far more weight. More on air ambulance disputes.
Who Files the Most Disputes
| Initiating party or representative | Disputes initiated, Q4 2025 |
|---|---|
| HaloMD | 134,467 |
| Team Health | 75,762 |
| SCP Health | 50,451 |
| F&A Management | 39,683 |
| Radiology Partners | 36,312 |
| M&D Capital Advisors | 35,718 |
| QMACS, Inc. | 32,493 |
| Radix | 32,329 |
| US Anesthesia Partners | 17,174 |
| Gottlieb & Greenspan | 16,852 |
Source: CMS Table 8, Q4 2025, shown for a single quarter for the same reason as the table above. The ten parties in this table filed 471,241 of the 707,501 disputes initiated over out-of-network items and services in that quarter — 67% — and most of them are representatives filing on behalf of many clinicians across multiple states. Federal IDR is dominated by parties who file at scale, and the reason is not mysterious: process knowledge and batching are what make individual claims economic to dispute.
That concentration is the honest argument for using someone who does this repeatedly — not because a filing cannot be made alone, but because eligibility, timing and batching are where disputes are lost, and those are learned by volume. Roughly 19% of disputes closed in the second half of 2025 were found ineligible, and 15.0% in January–September 2026.