No Surprises, New Developments: GAO Study Offers Early Look at How the No Surprises Act Is Shaping Provider Networks

The U.S. Government Accountability Office (“GAO”) has released a report examining how the No Surprises Act (“NSA”) may be influencing provider network participation and payment patterns in private health insurance markets. The report – entitled “Private Health Insurance: Provider Participation and Payments for Selected Services Before and After the No Surprises Act” – analyzes nationwide claims data from 2019 through 2023 and focuses on provider specialties most directly affected by the NSA’s surprise billing protections.

A copy of the GAO’s full report can be found here and a “highlights” page can be found here.

Background on the No Surprises Act

The NSA, enacted in December 2020 and effective January 1, 2022, generally prohibits providers from issuing balance bills to patients for certain out-of-network services, including emergency services and certain services furnished at in-network facilities. Under the NSA, patients are typically responsible only for the in-network cost-sharing amounts they would have paid had the services been rendered in-network. Meanwhile payment disputes between providers and payers are resolved through negotiation or an Independent Dispute Resolution (“IDR”) process established by the NSA. Because these provisions alter the dynamics of negotiations between providers and insurers, policymakers and stakeholders have closely monitored whether the NSA may be influencing provider participation in health plan networks or affecting reimbursement trends across certain specialties. GAO’s new report provides an early look at whether those market dynamics are beginning to shift.

GAO’s Review of Early NSA Market Effects

In its report, GAO analyzed a large national dataset of private health insurance claims and focused on four specialties that historically generated a significant share of surprise billing disputes: emergency medicine, radiology, anesthesiology, and air ambulance services. The analysis reviewed both facility-billed claims (typically submitted by hospitals) and professional claims (typically submitted by physicians or physician groups). This bifurcated approach allowed GAO to examine changes in network participation and payment patterns across multiple provider types. GAO also supplemented its quantitative analysis by interviewing representatives from twenty stakeholder organizations, including provider associations, insurers, and state insurance departments, to gather perspectives on how the market may be responding to the NSA.

Network Participation Trends

One of GAO’s central areas of analysis involved examining whether provider participation in insurer networks has changed following implementation of the NSA. To assess this issue, GAO analyzed the percentage of claims billed as in-network for the selected specialties over time. Increases in the share of in-network claims may indicate greater participation in health plan networks, while decreases may signal the opposite.

GAO found that in-network participation increased in three of the four specialties examined after the NSA took effect (emergency medicine, radiology, and anesthesiology). In other words, for those specialties, the proportion of claims billed as in-network rose in the years following the NSA’s implementation. These findings may suggest that some providers have chosen to participate more actively in insurer networks following the enactment of the NSA, although GAO cautions that multiple factors may influence network participation and the data alone does not establish a direct causal relationship.

Emergency medicine, in particular, provides an effective example of the broader trend observed in the report. Specifically, GAO found that the percentage of emergency medicine claims billed as in-network declined in the years leading up to the NSA’s implementation but increased again after the law took effect. This pattern appeared in both facility-billed claims submitted by hospitals and professional claims submitted by physicians or physician groups. According to GAO, the post-implementation increase in in-network claims may indicate that providers are increasingly participating in plan networks for these services, although the report emphasizes that additional years of data will likely be necessary to fully understand how the NSA is affecting network participation decisions across the health care marketplace.

Air ambulance services represented the only specialty in GAO’s analysis that did not exhibit the same general pattern of increased in-network participation following the NSA’s implementation. GAO’s findings therefore suggest that market responses to the statute may vary by specialty, reflecting differences in market structure, provider concentration, and historical contracting practices across different segments of the health care system.

Payment Trends

In addition to examining network participation, GAO also analyzed changes in payment levels for selected services before and after implementation of the NSA. This portion of the analysis focused on inflation-adjusted payments for in-network services across the selected specialties to determine whether the NSA may have altered reimbursement trends in the private insurance market.

Overall, GAO found that payment patterns largely continued trends that existed prior to the NSA taking effect, rather than reflecting dramatic shifts attributable to the law itself. For example, inflation-adjusted payments for facility-billed emergency medicine services increased in 2022 and 2023, continuing a pattern of gradual growth that had already been observed between 2019 and 2021. At the same time, inflation-adjusted payments for professional emergency medicine services billed by physicians or physician groups declined during the same period, which also reflected trends that were already underway before the NSA was implemented.

These findings suggest that while the NSA may influence negotiation dynamics between providers and health plans, the early years of implementation have not yet produced clear evidence of major structural shifts in payment levels for the services examined. Instead, the available data indicates that reimbursement trends have generally followed pre-existing trajectories, at least during the initial years following implementation of the statute.

What’s Up Next? Additional Data May Clarify Long-Term Effects

GAO’s report represents an early federal effort to assess how the NSA may actually be influencing health care market dynamics. While the findings suggest modest increases in network participation for certain affected specialties, the report also emphasizes that many of the observed trends appear to be continuations of pre-existing patterns rather than dramatic market shifts attributable solely to the statute. As the NSA’s regulatory framework (including the federal IDR process) continues to evolve, additional years of data may provide a clearer picture of how the law is shaping negotiations between providers and health plans. Future analyses may also help policymakers better understand whether the statute ultimately affects provider network participation, reimbursement levels, and broader contracting behavior across the private health insurance market. As the implementation of the NSA continues to unfold, health care providers should remain attentive to regulatory developments, emerging IDR trends, and evolving contracting dynamics.

HaloMD is actively monitoring developments related to the No Surprises Act and its implementation. For additional insights into this and related regulatory developments, visit our News & Resources page.