Nestack Agent Care

Travel & Hospitality AI agent · Expense

Corporate-Travel Policy & Expense AI Agent

Check each claim against your policy and the accountable-plan rules, surface duplicates, outliers and exceptions as signals for a named approver, and route what cannot be substantiated to payroll.

4–6 weeksTypical delivery
Your stackDeployment
Signals onlyNamed approver
Agent CareAfter launch

What this agent does

A signal for an approver, not a verdict

In
01

Ingesting the claim, the receipts, the trip record and the policy in force for that traveller.

02

Normalising amounts, merchants, cost centres and trip legs, each carried with its own record.

Reason
03

Testing each claim against business connection, substantiation and the return of excess.

04

Reading a per diem as settling the amount only, and asking for time, place and business purpose.

05

Watching the substantiation and return windows, and surfacing a claim before either closes.

Decide
06

Raising duplicates, outliers and policy exceptions as signals for an approver to weigh.

07

Routing what cannot be substantiated to the approver, and onward to payroll as a wage item.

Out
08

Retaining the claim, the policy read against it, the substantiation, the edits and the approval.

09

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

Product statement

The agent checks and routes; a named approver decides, and the employer answers for how the arrangement itself is treated.

Example workflow

One claim, submission to approval

AgentHuman
1Claim submittedExpense tool, card feed, receipt capture or a traveller's own submission
2Context assembledReceipts, the trip record, the cost centre and the policy in force for that traveller
3Claim reviewedPolicy read, substantiation, flags
4Controls appliedBusiness-connection checks, substantiation checks, window checks, flags and confidence threshold
No human action required

Stages 1 to 4 run unaided, and nothing is reimbursed at any of them — the agent is checking, and the approver's lane opens at the confidence gate.

5DecisionBranches at the confidence threshold
High confidence

Goes to the named approver to release.

Low confidence

Adds a finance read first.

Approver releases

The claim is held with its policy read, its flagged lines and the confidence.

Approve · Query · Send to finance review
Approved — released for payment
6Expense systems updatedOnly where write access and approval policy allow it
7Outcome evaluatedFlag outcomes, override rates, substantiation gaps and items reclassified after payment
Overrides

Every approver override is counted in the evaluation.

What should not run autonomously

Human approval stays in control

Outside the boundary — human approval required8 items
Paying out a claim, or moving money against one.
Waiving substantiation for time, place or purpose.
Extending a substantiation or repayment deadline.
Calling a claim fraudulent, or naming a person.
Automation boundaryAgent acts unaided
Read each claim beside the policy in force for that traveller.
Test business connection, substantiation and return of excess.
Surface a duplicate or an outlier as a signal to weigh.
Flag what an approver must decide, and hold the claim there.
Any write happens inside the boundaries agreed at implementation, never ahead of approval.
Deciding whether a trip is safe for an employee.
Approving or refusing travel against a risk score.
Treating an unsubstantiated item as written off.
Changes to policy, thresholds or approval limits.

Example output

One claim, annotated

Everything the agent raises is attached to the claim and the policy it was read against.

Expense review output · single claimIllustrative example
Claim
Flagged line
Amount claimed
Source of record
Confidence
Standing
Two-night domestic trip
Meal claimed on a per diem, with no business purpose recorded against it
$142.60
Policy and trip record
88%
Signal for the approver
As receivedTaken from the claim, the receipts and the policy in force — nothing on this side is decided by the agent.
Records used Policy in force Trip and card record Prior approver reads
Why this is flaggedA per diem settles the amount and nothing else — time, place and purpose are still missing.
ActionApproveQuerySend to finance review
What the score decidesBelow the configured threshold the claim picks up a finance read before it reaches the approver.

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 claimFrom the claim and the policy
03Checking

Check against the policy

Read each claim against your written policy, the trip record and the accountable-plan requirements.

01Approved path

A flag is not a finding

Routine claims reach the approver already checked and already carrying what substantiates them.

02Human review

Send review to what money turns on

A duplicate, an outlier or an exception is a signal an approver weighs. The agent does not detect fraud and does not say that anyone committed any.

04Build an evidence trail

The claim, the policy and substantiation behind it and the approver who released it stay on the report.

Integrations

Typical integrations

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

Expense platformsSAP Concur · Expensify
Navan · Coupa · Brex
Card and payment feedsCorporate card issuers
Bank and settlement feeds
Travel and booking dataBooking tools · agencies
Itinerary and trip records

Agent

Corporate travel policy & expense

Reads the claim
Checks the policy
Holds for approval

Finance and payrollERP · general ledger
Payroll 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 payment

The layers nest. What each one misses is named in the map below.

L6 · Outermost — last line of defenceInward → L1 · closest to the model
L6Rollback / safe modeFall back to policy checking alone when evaluation or production signals degrade.Roll back
L5Version monitoringTrack model, prompt, policy-rule and threshold configuration changes.Track
L4TraceabilityRecord the claim, the policy read, the flags, the edits and the approval time.Record
L3Approver releasesHold claims for the named approver; it governs release, not whether an approved claim is sound.Gate
L2Policy guardrailsTest claims against business connection, substantiation and the windows; a failure returns the claim.Restrict
L1Confidence thresholdsRoute low-confidence claims to a finance read before the approver sees them.Require review
Model coreClaim reviewed — the policy read, the substantiation, the flags and confidence
L1 – L2Test whether a claim may stand
L3Puts the release in an approver's hands
L4 – L5Keep the claim and the substantiation behind it
L6Reverts to policy checking when signals degrade

How Nestack evaluates it

Evaluate the review workflow — not only the decision on one claim.

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

Surface — the claim the approver reads
Depth of coverage ▼
E1Final-output evaluationDid the policy read match the policy actually in force for that traveller?
E2Step-level evaluationDid the agent use the right trip record, cost centre and policy version?
E3Tool evaluationDid it read and write the correct claim and the correct report?
E4Confidence calibrationDo low-confidence claims actually attract more approver overrides?
E5Slice evaluationHow does performance change across specific claim types?
E6Business outcomeHow many claims were reclassified or corrected after payment?
Floor — the payroll position the employer carries

Failure modes

Where each failure originates in the agent

Seven failure modes, placed at the stage each one originates.

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

Wrong policy version read

A claim is checked against a policy that no longer applies.

Stage gathersClaims, receipts, trip records and the policy
02 · Reasoning2 modes
CZ-04

Per diem read as complete

The amount is taken to settle time, place and purpose too.

CZ-06

Flag read as a finding

A signal is written up as though it accused a person.

Stage proposesPolicy read, substantiation and confidence
03 · Tool / write2 modes
CZ-02

Released without an approver

A claim reaches payment with no person behind it.

CZ-05

Substantiation window missed

A claim passes the deadline before anyone is asked.

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

Risk note read as clearance

A travel-risk line is taken as a decision that a trip is safe.

Stage returnsThe claim the approver releases for payment
05 · Change / Version1 mode
CZ-07

Silent policy regression

A model or rule change loosens what the agent will pass.

Stage tracksModel, prompt, policy rules and threshold config
Sev-1 · a claim released unapproved Sev-2 · a wage event passes as expense Sev-3 · policy data degrades, claim to review

Affected slices

Overall quality can hide one bad cohort

Every number in this table is a ratio, and the denominator is what matters. Routine receipted claims sit at the bottom The cohorts that carry it are named, not averaged away..

Slice performance — reported separately, not only in aggregateIllustrative example
SliceFailure rateLift Lift vs. thresholdStatus
Per diem claims7.2%3.5× Review
Claims near a window edge4.5%2.2× Review
Flagged duplicates and outliers2.9%1.4× Watch
Routine receipted claims1.6%0.8× Normal
Bar: approver-override-rate lift vs. routine-receipted baseline · scale 0–4.0× · tick marks the 2.0× review threshold 2 of 4 slices over threshold

Evidence-linked improvement

A cycle ends in a standing test

A cycle is done when the miss has become a test the next release has to survive. That suite is what the next claim through review is measured against.

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

Approver-override rate rises in a claim slice.

02Diagnose

The claims themselves come first — the receipts, the policy version read against them and the flags raised — and they are read until the cause narrows to one.

03Improve

Version-stamp the change and attach the claims that exposed it.

04Verify

The affected cases run again, and a fail stops the release.

05Learn

It becomes a standing test, and the policy notes change with it.

Learn → DetectThe return edge. The next detection is measured against a longer suite.

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, review workflow, evaluation, integration, then production validation and handover.

Workstream Week 1Week 2Week 3Week 4Week 5Week 6
01Expense and travel policy discovery and boundaries.
02Expense, card and trip source assessment.
03Policy, substantiation and approval-limit rule mapping.
04Claim ingestion and normalisation.
05Policy-check logic and record binding.
06Confidence scoring and flag routing.
07Approver release workflow.
08Expense and payroll integration.
09Substantiation and window cases.
10Guardrails and approval controls.
11Claim-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 entity, one policy ProductionProduction expense systems AdvancedMultiple entities / policies
Introduced at Pilot
Checking against your policy
Approver release
Review-quality baseline
Introduced at Production
Reporting by cost centre
Approval workflow in your systems
Approved write-back
Expense-system integration
Introduced at Advanced
Multi-entity policy sets
Multi-stage finance approvals
High claim volume
Multi-entity approval 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 written policy and approval limits Claim ingestion and policy mappingWeek 1
02Claims you have already reviewed Review baseline, policy extraction and record bindingWeek 2
03Your substantiation rules and who approves Policy, substantiation and approval-limit rule mappingWeek 1
04Access to relevant APIs, feeds or exports Expense, card and trip-record assessment, then integration setupWeek 2
05Claims you would not want reimbursed Substantiation cases and failure-mode testingWeek 4
06What must reach an approver before money moves Confidence scoring, flag routing, guardrails and approval controlsWeek 3
07Named approvers to release claims 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

Phases are drawn over the weeks they actually occupy, which is why week 5 doubles up rather than padding.

Phase W1W2W3W4W5W6
Discovery W1
Build W2 – W3
Evaluate W4 – W5
Pilot & Launch W5 – W6
Week focus W1Expense workflow discovery, policy mapping and the automation boundary W2Expense-system integration and the review baseline W3Review workflow, confidence logic and approval controls W4Substantiation cases, window guardrails and failure-mode testing W5Payroll integration, pilot claims and targeted corrections W6One reporting cycle reviewed under finance, then handover
Reading the bandA bar covers the weeks its work is named in, and nothing else. The week 5 overlap is real, not padding.
At the end of W6The last checks clear on live claims and monitoring moves to Agent Care.
DurationSix-week plan shown · typical delivery 4–6 weeks depending on scope confirmed in discovery.

Next step · Travel & Hospitality AI agent

Build an expense agent that flags, and never accuses.

An approval outside the accountable-plan rules is not a policy exception; it is a payroll-tax event, and it attaches to everything paid under the arrangement rather than to the item that was waved through. So bring the three things that decide it — your written policy, the substantiation you actually require, and the named approver who releases money. This is a finance and tax control, not a spend-tracking tool.

Nestack Agents · Corporate travel and expenseAGT-TH-13 · Agent Care available after launch