NSA Surprise Billing Compliance: IDR Data Analysis 2026

The No Surprises Act (Pub. L. 116-260, effective January 1, 2022) is federal legislation that protects patients from unexpected medical bills in two primary contexts:

1. Emergency services. Insurers must cover emergency services at in-network cost-sharing rates, regardless of whether the treating provider or facility is in-network. Providers cannot bill patients more than the in-network cost-sharing amount.

2. Non-emergency services at in-network facilities. When a patient receives scheduled care at an in-network facility, out-of-network providers (anesthesiologists, radiologists, assistant surgeons) cannot send the patient a separate "surprise" bill. The insurer pays the out-of-network provider, and any dispute over the rate is handled via the Independent Dispute Resolution (IDR) process.

The IDR mechanism. When a provider and insurer cannot agree on a payment rate for an NSA-covered service, either party can initiate IDR. A certified IDR entity (a neutral arbitrator) reviews both parties' offers and must choose one — baseball-style arbitration. The IDR entity is instructed to consider the Qualifying Payment Amount (QPA) — the median in-network rate for the same service in the same market — as a primary benchmark.

Machine-readable files (MRFs). The NSA also requires insurers to publish in-network negotiated rates, allowed amounts for out-of-network services, and drug prices in machine-readable format. The MRF requirement aims to enable price comparison by employers, researchers, and patients.

Source: CMS No Surprises Act IDR process quarterly reports (data.cms.gov/provider-data) and CMS MRF non-compliant issuer notices · Federal public domain (U.S.-Government-Works). Fonteum reports CMS-published figures; it does not independently audit any insurer or dispute outcome.

CMS's original IDR volume projection (~22,000 disputes per year) was based on estimates of how often providers and insurers fail to agree on payment during the 30-business-day open negotiation period. The actual volume revealed the projection's assumptions were deeply wrong.

Why volume exceeded projections by 26×:

1. QPA anchoring. IDR entities were initially instructed to treat the QPA as the presumptive correct rate — but providers viewed this as an artificial anchor below their historical contract rates. The high provider win rate (71%) validated that the QPA was often below fair market value for specialty services in certain markets.

2. Emergency medicine and anesthesiology concentration. These specialties are structurally out-of-network in many hospital settings because hospital contracts are facility-level, not specialty-level. The volume of NSA-covered services was far higher than CMS modeled.

3. Batching strategies. Some providers filed disputes in batches — grouping similar services under single IDR filings — which inflated "dispute count" relative to individual patient encounters.

4. Low marginal cost of filing. The filing fee ($350 per party in initial rules) was low relative to the revenue at stake, incentivizing providers to dispute nearly any QPA they believed was below market.

CMS subsequently raised filing fees and issued guidance tightening batching rules in mid-2023. The annualized run-rate declined after these rule changes, but remained substantially above the original projection.

Source: CMS No Surprises Act IDR process quarterly reports (data.cms.gov/provider-data) and CMS MRF non-compliant issuer notices · Federal public domain (U.S.-Government-Works). Fonteum reports CMS-published figures; it does not independently audit any insurer or dispute outcome.

The 71% provider win rate is the headline finding from CMS's first-year IDR data. It is important to interpret this correctly:

What it means. In 71% of completed determinations, the certified IDR entity selected the provider's offer rather than the insurer's offer. Since IDR is baseball-style (the entity must pick one offer, not split the difference), a 71% provider win rate means the provider's offer was judged "closest to the correct market rate" in 71% of cases.

What it does not mean. It does not mean providers prevailed 71% of the time from a litigation standpoint. Many disputes settle during the 30-day open negotiation period before reaching IDR. IDR completion data reflects only disputes that were not settled bilaterally — a self-selected pool likely to include more contested, higher-stakes cases.

Specialty concentration. Emergency medicine and anesthesiology account for a disproportionate share of both filing volume and provider wins. These are specialties where:

• Historical contract rates often exceeded the QPA (which is a median of in-network rates, including lower-rate contracts).
• The facility and the physician may contract separately, leaving the physician perpetually out-of-network.
• The average claim value is high enough to make IDR filing economically rational even after the filing fee.

Radiology and laboratory. These specialties showed lower provider win rates (~55–60%) relative to emergency medicine, reflecting tighter QPA alignment with historical contract rates.

The 1.7× QPA multiple in the average determination means that the median IDR outcome awarded providers 70% more than the insurer's proposed QPA — a significant gap that has prompted ongoing litigation over the QPA calculation methodology.

Source: CMS No Surprises Act IDR process quarterly reports (data.cms.gov/provider-data) and CMS MRF non-compliant issuer notices · Federal public domain (U.S.-Government-Works). Fonteum reports CMS-published figures; it does not independently audit any insurer or dispute outcome.

The MRF transparency requirement obligates all health insurers to publish:

1. In-network negotiated rates by plan, provider, and service code (machine-readable).
2. Allowed amounts for out-of-network services.
3. Prescription drug pricing information (a subsequent phase).

Compliance timeline:

• January 2022 (initial deadline): CMS estimated ~78% of issuers published compliant MRFs at launch. The remaining 22% published no file, published files in incorrect formats, or published files with missing required fields.
• Mid-2023 (post-notice): After CMS issued written notices of non-compliance to approximately 100 issuers, the compliance rate rose to over 92%. Smaller regional and specialty insurers (health maintenance organizations serving single metropolitan markets) showed the most improvement.
• Ongoing non-compliance. The approximately 8% non-compliant rate as of mid-2023 persists largely among smaller issuers. CMS's enforcement posture has focused on notice and correction rather than civil monetary penalty, consistent with CMS's stated preference for voluntary compliance in the first years of implementation.

MRF usability challenge. Even among issuers publishing compliant MRFs, file usability is highly variable. MRF files can exceed 200GB in size (for large national plans with hundreds of millions of negotiated rate records). Standard CSV or JSON parsers cannot process these files without distributed compute infrastructure. This creates a de facto transparency gap: the data is technically published, but practically inaccessible to most users.

Fonteum's MRF compliance table (nsa_mrf_compliance) tracks issuer compliance status by quarter once the operator's Inngest cron populates it. The /research/nsa-compliance leaderboard will show per-issuer compliance scores when live.

Source: CMS No Surprises Act IDR process quarterly reports (data.cms.gov/provider-data) and CMS MRF non-compliant issuer notices · Federal public domain (U.S.-Government-Works). Fonteum reports CMS-published figures; it does not independently audit any insurer or dispute outcome.

IDR dispute volume is not uniformly distributed across states. CMS quarterly reports show consistent concentration in a handful of states:

Estimated state share of IDR volume (2022–2023):

Texas's 13% share is disproportionate to its ~8% national population share. This reflects a combination of factors: Texas has historically had high rates of physician out-of-network billing in emergency settings, and the QPA anchoring problem is more acute in markets where historical independent physician rates exceeded the network median significantly.

Medicare Advantage entanglement. Medicare Advantage (MA) plans are not covered by the NSA, but the MA market's large presence in Florida and Texas affects the broader billing ecology. States with high MA penetration often have more aggressive insurer rate-setting that bleeds into commercial market QPA calculations, amplifying the QPA gap.

Source: CMS No Surprises Act IDR process quarterly reports (data.cms.gov/provider-data) and CMS MRF non-compliant issuer notices · Federal public domain (U.S.-Government-Works). Fonteum reports CMS-published figures; it does not independently audit any insurer or dispute outcome.

• This study uses CMS aggregate reports, not the Fonteum DB tables. The nsa_idr_filing_rates and nsa_mrf_compliance tables are empty pending the quarterly Inngest trigger (nsa-compliance-quarterly cron: 15th of March, June, September, December). Numbers here are from CMS public quarterly reports and may not precisely match DB-derived figures when live.
• IDR data reflects completed determinations, not all disputes. A significant share of disputes settle during the 30-day open negotiation period before reaching IDR. The 71% provider win rate applies only to completed IDR determinations — not all initiated disputes.
• QPA calculation methodology is litigated. Multiple federal court decisions have challenged how CMS calculates the QPA, affecting how IDR entities weight it. The 1.7× determination-to-QPA multiple may shift as methodology guidance evolves.
• MRF compliance rates are self-reported. CMS's compliance tracking relies on issuer submissions and public monitoring — not independent audit. The ~92% compliance rate reflects observed published MRFs, not confirmed MRF accuracy.
• Batching rule changes affect volume comparability. CMS tightened batching rules in 2023, making year-over-year dispute count comparisons difficult. Post-guidance volume is not directly comparable to pre-guidance volume.
• No individual claim or patient data. All figures are aggregate. No patient records, individual provider billing histories, or insurer-specific rate data are surfaced in this study.
• Not a quality or endorsement claim. IDR win rate and MRF compliance are regulatory compliance metrics, not quality ratings. Fonteum does not endorse, rate, or warn against any insurer or healthcare provider.

Source: CMS No Surprises Act IDR process quarterly reports (data.cms.gov/provider-data) and CMS MRF non-compliant issuer notices · Federal public domain (U.S.-Government-Works). Fonteum reports CMS-published figures; it does not independently audit any insurer or dispute outcome.

Permitted with attribution to Fonteum Research and a link back to this page. Suggested citation:

Fonteum Research. NSA Surprise Billing Compliance: IDR Data Analysis 2026. Published 2026-05-26. https://fonteum.com/research/nsa-surprise-billing-compliance

The underlying CMS IDR and MRF compliance data is a U.S. Government Work in the public domain (https://www.usa.gov/government-works). Direct citations to CMS should reference https://www.cms.gov/nosurprises/policies-and-resources/independent-dispute-resolution-data and https://www.cms.gov/files/document/machine-readable-files-report.pdf.

For the live leaderboard with per-issuer composite compliance scores, see /research/nsa-compliance.