A payroll rollout taught me the friction is never the integration. It is funding caps, routing permissions, and what can clear directly versus what has to detour through a sponsor bank. That is why the Fed's new payment-account RFI matters - access is becoming a design decision, not just a policy one.
A duplicate API call looks harmless until two payments clear and operations is left explaining the gap. The same error behaves differently on every rail - ACH hides it until batch, RTP and FedNow clear it instantly and final, wire forces a manual recall. On a multi-rail platform, governance is the architecture.
From March 2026, Nacha standardizes the ACH Company Entry Description as PAYROLL or PURCHASE for those payment types. It sounds trivial, but a free-text field becoming a dependable category is what finally lets reconciliation automation stick on a rail that still moves tens of billions of payments a year.
The CFPB finalized US open banking under Section 1033 in October 2024, a federal court enjoined enforcement a year later, and the rule is now back in reconsideration. The data layer that survives that whiplash is the deliverable, not the API. Build for reversals, not launch day.
Since October 2025, euro credit transfers run a Verification of Payee check before they settle, and a name-IBAN mismatch triggers an alert. It hits US treasuries paying EUR vendors and payroll as hard as it hits EU banks, and the same name checks are a fair bet to reach FedNow and RTP next.
FedNow matched RTP at a $10M network limit in November 2025 and added new risk rails - a receiver-account pre-check pilot, ScamClassifier reporting, an Exception Resolution Service, and 1,500+ banks live. Instant is treasury cash now, and batch-era controls just got a 24/7 bypass.