The 2027 U.S. FHIR mandate (CMS-0057-F) is reshaping how payers, providers, and health IT vendors exchange data and manage prior authorizations. By 2027, impacted health plans must implement FHIR-based APIs for patient access, provider access, payer-to-payer exchange, and electronic prior authorization with strict timelines. We break down what the rule really means in practice and show how Data InterOps helps organizations design, build, and operationalize FHIR-first workflow