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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.

Typical delivery
4–6 weeks
Deployment
Your stack
Controller review
Pre-payment
After launch
Agent Care

What this agent does

Verifies the change, not the vendor

In

  1. 01

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

  2. 02

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

Reason

  1. 03

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

  2. 04

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

  3. 05

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

Decide

  1. 06

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

  2. 07

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

Out

  1. 08

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

  2. 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

  1. 1Request receivedVendor email, onboarding portal, ERP change form or connected intake
  2. 2Context assembledExisting record, prior verifications, screening history and configured rules
  3. 3Change screenedScreening result, ownership signal, callback status and confidence
  4. 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

  1. 6Vendor-master system updatedOnly where write access and approval policy allow it
  2. 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 required

8 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 boundary

    Agent 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 change

Illustrative example
Vendor
Established vendor, new bank details
Change requested
Bank-detail change received by email; routing and account both differ from the record
Payee-name check
Close match
Screening result
No direct hit — aggregate ownership under review
Confidence
61%
Callback basis
Independently sourced contact, not the number in the request

As received

Taken 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 hold

A close match and an unresolved callback are evidence for the controller.

What the score decides

Below the configured threshold the change picks up a second verification pass before.

Action

ApproveRejectEscalate to compliance

Value

Where AI adds value

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

Where the value lands

Value 01 – 04

Every vendor

From 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.

04

Build 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 systems

    • SAP Ariba
    • Coupa
    • NetSuite
    • Oracle Procurement

  • Screening & sanctions data

    • OFAC SDN
    • EU & UK lists
    • Ownership & ID verification APIs

  • Payment & banking data

    • VoP / CoP results
    • W-9 / W-8 tax documents

Agent

Vendor master & payment verification

  • Reads the record
  • Screens the change
  • Holds for approval

  • Workflow

    • Email
    • ticketing
    • Approval systems

  • Observability & evaluation

    • OpenTelemetry
    • 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 defence

Inward → 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 – L2
Test whether the change may stand
L3
Puts the release in a controller's hands
L4 – L5
Keep the change and the verification behind it
L6
Holds 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

  1. E1Final-output evaluationDid the screening result and callback outcome match the record?
  2. E2Step-level evaluationDid the agent use the right contact, screening lists and configured rules?
  3. E3Tool evaluationDid it read and write the correct vendor and the correct field?
  4. E4Confidence calibrationDo low-confidence changes actually attract more controller overrides?
  5. E5Slice evaluationHow does performance change across specific vendor cohorts?
  6. 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 lifecycle

Direction of processing →

  1. 01 · Retrieval

    1 mode

    • VM-03

      Superseded callback contact

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

    Stage gathers

    Vendor submission, screening history and callbacks

  2. 02 · Reasoning

    2 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 proposes

    Screening result, callback outcome and confidence

  3. 03 · Tool / write

    2 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 writes

    Only where write access and approval policy allow it

  4. 04 · Output

    1 mode

    • VM-01

      Segregation-of-duties breach

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

    Stage returns

    The change the controller approves

  5. 05 · Change / Version

    1 mode

    • VM-07

      Silent backup-withholding gap

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

    Stage tracks

    Model, 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
See the complete Accounting failure-mode catalogue

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 aggregate

Illustrative example
SliceFailure rateLiftLift 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 stages

Switchback — the path turns at Improve and returns at Learn

  1. 01

    Detect

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

  2. 02

    Diagnose

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

  3. 03

    Improve

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

  4. 04

    Verify

    A failing verification case holds the release until it clears.

  5. 05

    Learn

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

  6. Learn → Detect

    The 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

  1. 01Vendor workflow discovery and boundary definition.Week 1
  2. 02Vendor-master and payment-source review.Week 1, Week 2
  3. 03Screening and verification-policy mapping and rule mapping.Week 1, Week 2
  4. 04Submission ingestion and normalisation.Week 2
  5. 05Screening logic and ownership aggregation.Week 2, Week 3
  6. 06Confidence scoring and callback routing.Week 3
  7. 07Controller approval workflow.Week 3, Week 4
  8. 08Vendor-master and ERP integration.Week 5
  9. 09Bank-change regression cases.Week 4, Week 5
  10. 10Guardrails and release controls.Week 4
  11. 11Vendor-trail instrumentation.Week 5, Week 6
  12. 12Deployment, documentation and Agent Care handover.Week 6

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 tierPilotOne vendor source, one entityProductionProduction vendor-master systemsAdvancedMultiple 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 priceFrom $5,000From $8,000Custom quote
Final build price
Confirmed after discovery based on integrations, workflow complexity, transaction volume, approval controls and deployment requirements.
Separate from build
Build 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.

  1. 01Your vendor intake fields and master-file structure

    Vendor-master ingestion and field mapping

    Week 1

  2. 02Representative historical vendor onboardings

    Onboarding baseline, screening setup and ownership mapping

    Week 2

  3. 03Your screening rules and approved contact sources

    Screening and verification-policy mapping

    Week 1

  4. 04Access to relevant APIs, feeds or exports

    Vendor-master and payment-source assessment, then integration setup

    Week 2

  5. 05Changes you would not want released

    Impersonation cases and the evaluation suite

    Week 4

  6. 06What no vendor change may skip

    Confidence scoring, callback routing, guardrails and approval controls

    Week 3

  7. 07Named controllers to review flagged vendors

    Controller approval workflow, then pilot and production validation

    Weeks 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

W1

W2

W3

W4

W5

W6

  1. DiscoveryW1
  2. BuildW2 – W3
  3. EvaluateW4 – W5
  4. Pilot & LaunchW5 – 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 band
A bar covers only the weeks its work is named in. The week 5 overlap is real, not padding.
At the end of W6
The final checks clear on live changes and monitoring moves to Agent Care.
Duration
Six-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.

Typical delivery
4–6 weeks
Deployment
Your vendor-master stack
Controller approval
Pre-payment
After launch
Agent Care available

Nestack Agents · Vendor master & payment verification

AGT-ACC-21 · Agent Care available after launch

Build a vendor-master agent

Four questions so the call starts from your actual setup — then pick a time that suits you.

About you
Your vendor master

No obligation. We’ll map the workflow, name the automation boundary and tell you if an agent is the wrong answer.