The evidence has to survive somebody who is paid to doubt it.
Commercial and regional banks, custodians, clearing houses and market infrastructure operators, where the integration is only finished when it can be explained to an examiner.
Who has to be convinced, and of what
The room that decides this contains an internal auditor, a risk committee, and eventually a supervisor. None of them is evaluating the ledger. They are evaluating whether the institution can evidence what it did, on the timeline the rules contemplate, when something goes wrong.
That changes what the work has to produce. An integration that moves value correctly but cannot produce a timestamped account of an incident is not finished, and the part that is missing is the part that takes longest to add afterwards.
Two questions worth answering first
- Could you evidence detection-to-notification for a payments incident on the timeline the rules contemplate, from instrumentation rather than from recollection? If the answer depends on which four people are available that morning, the answer is no.
- When your core is in its maintenance window, what happens to a payment that arrives on the ledger? The ledger does not have a maintenance window. Whatever absorbs that difference is either a designed component or a person.
What is forcing the decision
The message format already moved
ISO 20022 is the settled format for cross-border instructions, and the structured-address mandate lands in November 2026. The data those messages need has to come out of systems that were never asked for it in that shape.
The posting model is the constraint
A ledger settles continuously. A core that posts in batch with a cut-off does not. Everything downstream — reconciliation, break handling, reporting — inherits whichever of the two you fail to reconcile.
Availability is assessed, not asserted
A maintenance window in which payments stop is a finding when the counterparty ledger has no window at all. So is a failover procedure that has been documented and never rehearsed.
The capabilities this usually turns on
All twelve are in scope. These four are where the work concentrates for an organisation of this kind, and where an assessment tends to find the thing that moves the date.
ISO 20022 message mapping
pacs.008, pacs.009 and camt reporting mapped to ledger transactions and back, including the fields that have no counterpart on either side and have to be carried somewhere.
Settlement and posting model
Continuous or batch posting, cut-off behaviour, and what settles outside business hours without an operator present.
Reconciliation and break management
Ledger state against core state against the general ledger, on a schedule, with a documented path for the morning they disagree.
Availability, failover and continuous operation
What happens during the maintenance window, during a failover, and during the week of the core upgrade — measured against a standard that assumes payments do not stop.
Three ways in, of equal standing
There is no fixed ladder here and no engagement you have to buy before another one becomes available. If you already know what your estate does, an assessment is a formality you can skip. If you do not, four weeks of measurement costs less than the first wrong assumption.
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