Out-of-network (OON) balance billing, commonly known as surprise billing but better described as a surprise gap in health insurance coverage, occurs when an individual with private health insurance (vs a public insurer such as Medicare) is administered unanticipated care from a physician who is not in their health plan's network. Such unexpected OON care may result in substantial out-of-pocket costs for patients. Although ending surprise billing is patient centric, patient protective, and noncontroversial, passing federal legislation was challenging given its ability to disrupt insurer-physician good-faith negotiations and thus impact in-network rates. Like past proposals, the recently passed No Surprises Act takes patients out of the middle of insurer-physician OON reimbursement disputes, limiting patients' expense to standard in-network cost-sharing amounts. The new law, based on arbitration, attempts to protect good-faith negotiations between physicians and insurance companies and encourages network contracting. Radiology practices, even those that are fully in network or that never practiced surprise billing, could nonetheless be affected. Ongoing rulemaking processes will have meaningful roles in determining how the law is made operational. Physician and stakeholder advocacy has been and will continue to be crucial to the ongoing evolution of this process. © RSNA, 2021.