The Accredited Standards Committee (ASC) X9’s ISO 20022 Market Practices Forum created this “ISO 20022 Message Comparison Matrix” to document and compare how different U.S. payment platforms have implemented ISO 20022 messages and versions for various payment-related functions.

While ISO 20022 was designed to enable consistent, structured financial messaging across platforms and countries, in practice, differences in how it’s implemented by systems like RTP, FedNow, CHIPS, Fedwire, and SWIFT’s CBPR+ can limit true interoperability. Although ISO 20022 is designed for interoperability, the platforms vary in which specific messages and versions they adopt for equivalent functions. This diversity is due to the unique operational needs and adoption timelines of each infrastructure

These differences include:

• Message versions: Not all platforms adopt the latest ISO 20022 versions at the same time.
• Optional vs. mandatory fields: Each system may treat certain data elements differently—what’s required in one might be optional or unused in another.
• Usage guidelines: Platforms publish their own implementation guidelines (MPGs), tailoring the standard to their needs.
• Functionality coverage: Some systems support only a subset of ISO 20022 messages (e.g., payments vs. account reporting).

The ASC X9 “ISO 20022 Message Comparison Matrix” is useful for stakeholders who need to understand and navigate these variances—for example, financial institutions working with multiple payment rails or fintechs integrating with various platforms.

Observations from the Matrix:

• Generally Aligned: Most platforms use the same message types and versions for core use cases.
• Notable Differences: Example—RTP uses pacs.008 for Payment Returns, while FedNow uses pacs.004.
• Platform-Specific Implementations: Some messages (e.g., drawdown debits or TCH-specific admin messages) are unique to certain platforms and not applicable elsewhere.

Intended Benefit:

The matrix aims to support banks, FIs, and service providers in developing more modular, adaptable systems that can handle message updates and platform differences with minimal disruption.

Living Document:

The matrix is designed to be updated annually to reflect evolving platform adoption and ISO 20022 version updates.