ISO 20022 is not a messaging upgrade—it is a fundamental restructuring of how payment data flows. Its richer data fields materially improve fraud detection and sanctions screening, but migration strains legacy infrastructure. The ECB mandated 2025 compliance; FedNow is ISO-native; SWIFT is sunsetting legacy MT messages. Early movers are already stress-testing migration paths. Laggards face two compounding risks: vendor backlog as demand spikes, and operational exclusion from corridors that require ISO-compliant counterparties.