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Accounting AI agent · Vendor master

Vendor-Master & Payment-Verification AI Agent

Collect and validate vendor onboarding data, screen for sanctions and ownership risk, verify bank-detail changes out of band against a known contact, and hold what doesn't reconcile; vendor approval and payment release stay separate.

4–6 weeksTypical delivery
Your stackDeployment
Pre-paymentController review
Agent CareAfter launch

What this agent does

Verifies the change, not the vendor

In
01

A new vendor or a bank-detail change arrives from the onboarding portal, a vendor email or a connected ERP feed.

02

The vendor's submission is normalised against the master-file schema, with its original fields kept.

Reason
03

A screening pass checks the vendor and its named owners against sanctions and watch lists.

04

The controller's configured onboarding rules and tax-form requirements are applied to the vendor type.

05

The vendor's existing, independently verified contact — never the one in the request — anchors the callback.

Decide
06

A name match, a shared address or an unresolved callback is flagged against the vendor, never cleared by the agent.

07

Every flagged vendor and every bank-detail change is routed to the named controller for disposition.

Out
08

The submission, the screening result, the callback outcome and the disposition are retained against the vendor.

09

Execute write actions only inside the approval boundaries agreed during implementation.

Product statement

The agent proposes the change; the controller decides whether to release it, and payment release stays with a separate named person.

Example workflow

One vendor change, request to release

AgentHuman
1Request receivedVendor email, onboarding portal, ERP change form or connected intake
2Context assembledExisting record, prior verifications, screening history and configured rules
3Change screenedScreening result, ownership signal, callback status and confidence
4Controls appliedSanctions checks, ownership aggregation, callback verification and confidence threshold
No human action required

Stages 1 to 4 run unaided, and nothing changes on the vendor record at any of them — the controller's lane opens at the confidence gate.

5DecisionBranches at the confidence threshold
High confidence

Goes to the controller to approve.

Low confidence

Adds a second verification pass first.

Controller approval

The change is held with its screening result, its callback outcome and the confidence.

Approve · Reject · Escalate to compliance
Approved — released to update
6Vendor-master system updatedOnly where write access and approval policy allow it
7Outcome evaluatedVerification accuracy, overrides, escalations and payment outcome
Overrides

Every controller override is counted in the evaluation.

What should not run autonomously

Human approval stays in control

Outside the boundary — human approval required8 items
Approving a new vendor for payment.
Releasing a payment to any vendor.
Clearing a sanctions or watch-list hit.
Changing bank details on its own authority.
Automation boundaryAgent acts unaided
Collect and validate onboarding data and the required tax form.
Run screening and ownership aggregation against configured lists.
Verify bank-detail changes out of band against.
Flag what doesn't reconcile, and hold the record.
Any write happens inside the boundaries agreed at implementation, never ahead of approval.
Deciding a name match is a false positive.
Waiving the out-of-band callback.
Filing US beneficial-ownership reports.
Changes to screening rules or callback thresholds.

Example output

One vendor change, annotated

Everything the agent verifies is attached to the request it came from.

Verification output · single vendor changeIllustrative example
Vendor
Change requested
Payee-name check
Screening result
Confidence
Callback basis
Established vendor, new bank details
Bank-detail change received by email; routing and account both differ from the record
Close match
No direct hit — aggregate ownership under review
61%
Independently sourced contact, not the number in the request
As receivedTaken from the request and the existing vendor record — nothing on this side is inferred.
Evidence used Verified contact on file Prior verified callback Payee-name check
Why this holdA close match and an unresolved callback are evidence for the controller.
ActionApproveRejectEscalate to compliance
What the score decidesBelow the configured threshold the change picks up a second verification pass before.

Value

Where AI adds value

The same four claims, placed at the point in the workflow where each one applies.

Where the value landsValue 01 – 04
Every vendorFrom the vendor record on file
03Verification

Screen and verify from the record

Draw on the existing contact on file and the controller's configured screening rules.

01Approved path

A hit is not a decision

Under OFAC's ownership-aggregation rule, blocked ownership stacks across sanctions programmes — an entity can be blocked without appearing on any single list.

02Human review

Focus the controller on exceptions

Screening hits, ownership signals and unresolved callbacks are flagged, so the controller's read starts where fraud risk concentrates.

04Build an evidence trail

The change, the channel it was verified on and the officer who released it stay on the vendor record.

Integrations

Typical integrations

Five system groups connect to the same agent. Which of them are in scope is decided in discovery.

Vendor-master & ERP systemsSAP Ariba · Coupa
NetSuite · Oracle Procurement
Screening & sanctions dataOFAC SDN · EU & UK lists
Ownership & ID verification APIs
Payment & banking dataVoP / CoP results
W-9 / W-8 tax documents

Agent

Vendor master & payment verification

Reads the record
Screens the change
Holds for approval

WorkflowEmail · ticketing
Approval systems
Observability & evaluationOpenTelemetry · Langfuse
Supported monitoring/evaluation sources

Integration availability depends on the client's existing systems and API access.

Agent controls

Six layers between the model and the vendor record

The layers wrap one another. What gets past them all is set out in the map below.

L6 · Outermost — last line of defenceInward → L1 · closest to the model
L6Rollback / safe modePull verification back to hold-only when evaluation or production signals degrade.Roll back
L5Version monitoringTrack model, prompt, screening-rule and policy changes.Track
L4TraceabilityRecord the request, the screening result, the callback and the disposition.Record
L3Controller approvalHold changes for the named controller; it governs release, not whether the match is right.Gate
L2Policy guardrailsTest changes against configured screening, callback and tax-form rules; a failure holds it.Restrict
L1Confidence thresholdsRoute low-confidence changes to a second verification pass before the controller sees them.Require review
Model coreChange screened — screening result, ownership signal, callback status and confidence
L1 – L2Test whether the change may stand
L3Puts the release in a controller's hands
L4 – L5Keep the change and the verification behind it
L6Holds the vendor at pending when signals degrade

How Nestack evaluates it

Evaluate the verification workflow — not only the final screen.

Coverage runs the whole depth of the workflow, and every layer is cut by slice.

Surface — the change the payment system sees
Depth of coverage ▼
E1Final-output evaluationDid the screening result and callback outcome match the record?
E2Step-level evaluationDid the agent use the right contact, screening lists and configured rules?
E3Tool evaluationDid it read and write the correct vendor and the correct field?
E4Confidence calibrationDo low-confidence changes actually attract more controller overrides?
E5Slice evaluationHow does performance change across specific vendor cohorts?
E6Business outcomeHow many changes needed a controller override after release?
Floor — the outcome the controller answers for

Failure modes

Where each failure originates in the agent

Seven failure modes, mapped to the stage each one starts at.

Agent lifecycleDirection of processing →
01 · Retrieval1 mode
VM-03

Superseded callback contact

The verification contact drawn from the record predates the vendor's last confirmed update.

Stage gathersVendor submission, screening history and callbacks
02 · Reasoning2 modes
VM-04

Ownership-aggregation rule missed

Ownership stacked across programmes crosses the block threshold with no single owner over it.

VM-06

Hit read as cleared

A fuzzy name match is treated as resolved without a target-match review.

Stage proposesScreening result, callback outcome and confidence
03 · Tool / write2 modes
VM-02

Low-confidence auto-release

Agent releases a bank-detail change despite an unresolved callback.

VM-05

Stale verification reused

A prior callback clearance is applied to a new bank-detail change.

Stage writesOnly where write access and approval policy allow it
04 · Output1 mode
VM-01

Segregation-of-duties breach

The same actor edits the vendor master and releases the resulting payment.

Stage returnsThe change the controller approves
05 · Change / Version1 mode
VM-07

Silent backup-withholding gap

A TIN-mismatch rule change stops flagging failed certifications without review.

Stage tracksModel, prompt, screening rules and callback policy
Sev-1 · a change releases outside the boundary Sev-2 · a bad account reaches a payment run Sev-3 · source degrades, change routes to review

Affected slices

An overall catch rate can hide one exposed tier

An overall catch rate can look strong while one exposed vendor tier absorbs most of the attempts. Nestack reports the held-for-review rate by vendor tier, not only in total.

Slice performance — reported separately, not only in aggregateIllustrative example
SliceFailure rateLift Lift vs. thresholdStatus
Bank-change requests by email only7.8%4.0× Review
New vendors onboarded under time pressure5.6%2.9× Review
Vendors sharing an address or account3.5%1.8× Watch
Established vendors, unchanged details1.9%0.8× Normal
Bar: held-for-review-rate lift vs. the unchanged-vendor baseline · scale 0–4.0× · tick marks the 2.0× review threshold 2 of 4 slices over threshold

Evidence-linked improvement

Every cycle closes on a case, not an explanation

A cycle shuts when the missed impersonation is a case the next release has to catch. That suite is what the next bank change handled is measured against.

Improvement cycle · five stagesSwitchback — the path turns at Improve and returns at Learn
01Detect

Held-for-review rate rises in a vendor tier.

02Diagnose

The bank-change email that read correctly is traced back to the callback that should have caught it, until the cause narrows to one.

03Improve

The change ships against a version, with the vendors that exposed it attached.

04Verify

A failing verification case holds the release until it clears.

05Learn

The case joins the standing suite and the callback rules move with it.

Learn → DetectThe return edge. The next bank change is checked against a suite one case longer.

Typical build scope

Twelve workstreams across six weeks

The build scope read against the delivery timeline. Week structure follows the six-week plan — discovery, sources, verification workflow, evaluation, integration, then production validation and handover.

Workstream Week 1Week 2Week 3Week 4Week 5Week 6
01Vendor workflow discovery and boundary definition.
02Vendor-master and payment-source review.
03Screening and verification-policy mapping and rule mapping.
04Submission ingestion and normalisation.
05Screening logic and ownership aggregation.
06Confidence scoring and callback routing.
07Controller approval workflow.
08Vendor-master and ERP integration.
09Bank-change regression cases.
10Guardrails and release controls.
11Vendor-trail instrumentation.
12Deployment, documentation and Agent Care handover.
12 workstreams · 6 weeks · bar shows the weeks a workstream is active — several run in parallel Final scope and sequence confirmed in discovery

Engagement tiers

What each tier includes

Rows are the capabilities named in each tier's scope. Higher tiers include everything below them.

Capability✓ in scope · — not at this tier PilotOne vendor source, one entity ProductionProduction vendor-master systems AdvancedMultiple entities / systems
Introduced at Pilot
Screening and verification to your rules
Controller approval
Verification-accuracy baseline
Introduced at Production
Reporting by vendor group
Approval workflow in your systems
Approved write-back
Vendor-master integration
Introduced at Advanced
Multi-entity and multi-currency rules
Multi-stage controller approvals
High vendor volume
Multi-entity vendor controls
Build price From $5,000 From $8,000 Custom quote
Final build priceConfirmed after discovery based on integrations, workflow complexity, transaction volume, approval controls and deployment requirements.
Separate from buildBuild pricing is separate from recurring Agent Care, which covers managed monitoring, evaluations, incidents and verified improvements after launch.

What we need from you

What you bring, and what we build with it

Each input maps to a piece of build scope and a week in the delivery timeline.

You bringWe build with it
01Your vendor intake fields and master-file structure Vendor-master ingestion and field mappingWeek 1
02Representative historical vendor onboardings Onboarding baseline, screening setup and ownership mappingWeek 2
03Your screening rules and approved contact sources Screening and verification-policy mappingWeek 1
04Access to relevant APIs, feeds or exports Vendor-master and payment-source assessment, then integration setupWeek 2
05Changes you would not want released Impersonation cases and the evaluation suiteWeek 4
06What no vendor change may skip Confidence scoring, callback routing, guardrails and approval controlsWeek 3
07Named controllers to review flagged vendors Controller approval workflow, then pilot and production validationWeeks 5–6
Nothing else is required Deployment, documentation and Agent Care handover are ours.

Delivery timeline

Four phases across six weeks

Each band sits on the weeks the work occupies, so week 5 runs evaluation and pilot together.

Phase W1W2W3W4W5W6
Discovery W1
Build W2 – W3
Evaluate W4 – W5
Pilot & Launch W5 – W6
Week focus W1Vendor workflow discovery, policy mapping and the automation boundary W2Source integration and the screening baseline W3Verification workflow, confidence logic and approval controls W4Evaluation suite, guardrails and failure-mode testing W5Vendor-master integration, pilot vendors and targeted corrections W6One payment cycle verified under the controller, then Agent Care handover
Reading the bandA bar covers only the weeks its work is named in. The week 5 overlap is real, not padding.
At the end of W6The final checks clear on live changes and monitoring moves to Agent Care.
DurationSix-week plan shown · typical delivery 4–6 weeks depending on scope confirmed in discovery.

Next step · Accounting AI agent

Build a vendor-master agent around your onboarding and verification chain.

Show us your vendor intake, your screening sources and who owns the callback. We'll map the verification workflow, set the automation boundary, and confirm where vendor approval ends and payment release begins.

Nestack Agents · Vendor master & payment verificationAGT-ACC-21 · Agent Care available after launch