The "Health Data Access, Transparency, and Affordability Act of 2026" amends the Employee Retirement Income Security Act of 1974 (ERISA) to significantly enhance transparency and data access for group health plans. It mandates that contracts between group health plans and "network service providers" – a broad category including insurers, third-party administrators, and pharmacy benefit managers – must ensure plan fiduciaries and their designated agents have comprehensive access to health claims and encounter information. This aims to empower plans to better understand and manage their healthcare expenditures and quality of care. Specifically, the bill requires network service providers to grant access to all claims and encounter data, including supporting documentation like medical records and policy documents, within 15 days or a shorter period determined by the Secretary. Contracts are deemed unreasonable if they limit the amount of data, restrict access to pricing terms (such as payment calculations, quality measures, and contract terms), or prevent the disclosure of fees charged to the plan. Furthermore, the legislation prohibits any contractual provisions that limit a plan's ability to audit, review, or access this crucial information, or to act on potentially erroneous or fraudulent claims. To ensure compliance, the bill specifies that information must be provided in standardized electronic formats, such as ASC X12N 837 for claims and ASC X12N 835 for claim payments, and accessible at no cost to the plan. It also introduces civil penalties of up to $10,000 per day for network service providers who violate these requirements, and voids any contractual terms that attempt to limit data access or indemnify providers against these penalties. While enhancing data access, the bill explicitly maintains consistency with HIPAA privacy and security regulations , ensuring protected health information remains secure.