US market entry for a European digital bank

The situation

A licensed European digital bank with a growing US customer base was pursuing a US banking charter and needed to move US dollars across the domestic rails — RTP for speed, FedWire for high-value finality, ACH for cost-efficient batch flows. Its core and public APIs were built for SEPA: IBAN-shaped counterparties, no concept of a routing number, an ACH file, or an ISO 20022 pacs message bound for a US network. And the charter timeline was uncertain from the start.

What we did

• Program and architecture. A phased twelve-month program — core and adapters, orchestration and sandbox, hardening, production and hypercare — with a parallel compliance track from week one, a dependency-mapped plan, and a risk register built around the things that actually slip: sandbox access, network-specific quirks, and certification lead times.
• ISO 20022 canonical layer. A schema registry across the pacs, camt, pain, and remt families; a message builder with field-level validation and cardinality checks; a bidirectional parser applying each network’s business rules.
• Three network adapters — RTP (pacs.008 / pacs.002 / camt.035), FedWire (pacs.008 / pacs.009 / camt), and ACH (ISO 20022 to NACHA file mapping) — behind one adapter interface, with a routing engine (RTP, then FedWire, then ACH by default) and idempotency-safe failover.
• Integration-surface evaluation. A source-level read of the bank’s public and partner APIs and SDKs that established where a US-domestic payment could — and could not — enter the core, and set the design constraints for idempotency, rate limits, and callback handling.
• Path-agnostic design. When the charter decision moved, we re-based the architecture so the same seam and the same adapters serve a sponsor-bank interim, an acquisition, or a refiled charter — only the counterparty at the seam changes.
• Compliance boundary. BSA/AML and OFAC touchpoints documented as data flows; the bank’s compliance engines own screening, the integration owns the audit trail.

The outcome

A sequenced, executable program and a rails architecture that did not depend on the regulatory outcome — with a certification path designed in parallel with the build plan.

What it shows

Foreign-bank US entry is a seam problem before it is a rails problem. Find where the US-dollar payment enters the core, put ISO 20022 at that seam, and the rest of the program stops depending on decisions you don’t control.