AI agents in banking · The build map · Brief 04

Fraud detection: a design brief for banks.

Last updated Sep 17, 2026 · standard answers for this use case · adjust them in the map

Fraud is the most permissive use case in regulatory terms and the most time-critical operationally. Detection itself is usually a validated model on live data; language models earn their place in triage, investigator assistance and customer contact, where speed and clarity matter and where the threat itself is increasingly generated by AI. The rule to design around: a block or a decline that touches credit is an adverse action, and a customer contact must not be mistakable for a scam.

Augmented callTier 2: act with approvalautonomy level 1

Fraud detection: The model prepares and may act within limits; a person approves anything that reaches a customer or cannot be undone. One model call with retrieval, tools and a structured output, inside code you control. Material but recoverable. The model may prepare and, within limits, act, with a person approving anything that leaves the bank or touches a customer.

PatternAugmented call. The task is well defined and the output can be checked. Most bank use cases should start here.KnowledgeTool calls to the system of record for anything live. Never retrieval for a balance, a case status or a limit.Delivery routeThrough a cloud platform: two third parties in the chain and a concentration question; often the faster route through security review.

Which steps belong to a person, the model and a system?

A PERSONTHE MODELA SYSTEM1
Detect
2
Triage and enrich
3
Act on the account
4
Contact the customer
5
Investigate and report
#StepOwnerNote
1DetectA systemThe validated scoring model on live transaction data.
2Triage and enrichThe modelSummarise the case, pull related activity via tools, propose a disposition.
3Act on the accountA systemHolds and blocks by rule, within limits; logged.
4Contact the customerA personOr a verified channel with a scripted, clearly identified AI assistant.
5Investigate and reportA personWith the model's file, and the SAR where required.

Which control layers carry the weight?

Governance and accountabilityCOREIdentity and entitlementsCOREAction gatewayCOREData and knowledgeSTANDARDModels and vendorsCORERuntime and orchestrationLIGHTObservability, evaluation and auditSTANDARDHuman oversight and escalationCORE

Each layer is described, with its controls and documents, on the control plane page.

Which rules and guidance does this design answer to?

DocumentAuthorityWhy it applies hereStatus
FIN-2024-Alert004 (Deepfake Media)FinCENThe threat picture: synthetic documents, voices and video at onboarding.In force
Regulation (EU) 2024/1689EU AI ActFraud detection is carved out of the high-risk credit category.In force
SR 26-2Federal ReserveFraud models validated in proportion to materiality.In force
ECOA / Regulation B adverse action (15 U.S.C. 1691(d); 12 CFR 1002.9)CFPBA fraud-driven decline of a credit application is still an adverse action.In force
DFS AI Cybersecurity Industry Letter (Oct 2024)NY DFSAI-enabled social engineering must appear in risk assessments and MFA design.In force
CFPB Chatbots in Consumer Finance (issue spotlight, 2023)CFPBCustomer-facing AI must not block access to a person or give wrong answers about rights.Final
SR 23-4Federal ReserveUS third-party risk management, including the model provider.In force
SB 26-189Colorado AI ActColorado: notice, explanation and human review for consequential automated decisions from Jan 1, 2027.Final
BCBS Third-Party Risk Principles (Dec 2025)Basel CommitteeNth-party supply chains and concentration on cloud providers.In force
BCBS ICT Risk Management Report (June 2026)Basel CommitteeHow supervisors look at ICT and cloud dependencies.Final
OCC Bulletin 2026-13OCCFor a national bank, the OCC's copy of the 2026 model-risk guidance.In force
NIST AI RMF 1.0NISTThe voluntary Govern, Map, Measure, Manage frame for everything model-risk guidance leaves out.In force

How will you know it works, before and after launch?

CODE CHECKS50%JUDGE MODEL30%HUMAN REVIEW20%
  • A golden dataset of at least 150 real cases with expected outputs, including adversarial inputs: wrong documents, unusual formats, prompts that try to change the task.
  • Code-based checks on every output: schema conformance, required fields, reconciliations against the system of record. Threshold: 99% or better before launch, every run in production.
  • Escalation evals: the cases that must reach a person do, on a held-out set, with precision and recall both reported.
  • The same suite reruns on every prompt change, model version change and retrieval change; a regression blocks the release. That is what ongoing monitoring and outcomes analysis mean in model-risk terms.

Where must a person be in the loop?

  • Per-action approval by a competent reviewer for anything customer-facing or irreversible; sampled review for the rest.
  • Validation proportionate to materiality, with monitoring for drift on inputs and outputs.
  • An escalation route to a person that the customer can reach in one step.
  • Monthly review of the evals and the exception log by the accountable owner.
  • The customer is told they are dealing with an AI system and can reach a person in one step.
  • A fraud decline on a credit product with no adverse-action reasons.
  • Customer outreach that trains customers to trust unverified AI voices.
  • Training data assembled outside the bank's data governance.

What will a validator or an examiner ask?

  1. Where is this system in your inventory, what tier did you assign, and who signed it off?
  2. What counts as a model here, and what does your validation cover for the parts that are not?
  3. Show me the data lineage behind the retrieval set and the training or tuning data.
  4. What can the system do without a person, and where is that written down?
  5. How do you know it is still working: which evals run, how often, and what happened the last time one failed?
  6. What did you do about the vendor: due diligence, contract, exit plan, concentration?
  7. Walk me through one wrong output from production and what the customer, if any, saw.
  8. Who can switch it off, and has that been tested?
  9. Show me how a customer reaches a person, and how long it took the last ten who tried.

What it does: scores and triages suspected fraud, and helps investigators and customers respond; the model prepares and may act within limits; a person approves anything that reaches a customer or cannot be undone.

Pattern: augmented call; tier 2: act with approval.

Rules it answers to: 4 documents across US, each linked in the brief.

How we know it works: a golden dataset, automated checks on every release, and human review at the level the tier demands.

What could go wrong and who answers: the accountable owner, the kill switch, the escalation route.

Which of the 100 largest US banks have put this use case on the record?

Every rule this brief cites, the morning it changes.

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