Sales-Tax & Compliance-Filing AI Agent

What this agent does

Prepares the return, holds the submission

Ingest sales and purchase transactions from supported ERP, billing, e-commerce and marketplace sources.

Normalise each line into customer, ship-from and ship-to, product or service code and date.

Reason

Determine taxability and rate for the jurisdiction a transaction sources to, on the date it sources.

Apply the registration footprint, exemption certificates and the client's agreed taxability positions.

Prepare each return and reconcile it to the transaction detail and the general ledger.

Decide

Detect tie-out variances, certificate gaps, nexus thresholds in reach and calendar changes.

Route variances, unregistered jurisdictions and low-confidence determinations to human review.

Out

Retain the workpaper trail — source detail, rate applied, tie-out and reviewer decision.

Assemble the filing package and hold it; submission and remittance need explicit authorisation.

→ Product statement

The agent prepares and reconciles inside the approval boundaries agreed during implementation; an authorised person submits the return and releases the money.

Example workflow

One filing period, end to end

AgentHuman

1Period drawnERP, billing, e-commerce and marketplace transactions

2Positions resolvedRegistration footprint, sourcing, taxability, certificates and the rates in force on each date

3Return preparedLiability by jurisdiction, schedules and the ledger tie-out

4Controls appliedTie-out variance, certificate coverage, nexus and calendar checks, and the confidence threshold

No human action required

Stages 1 to 4 run without a person in the loop — nothing has been filed or paid yet, so the lane stays empty until the gate.

5DecisionSplits on the tie-out and confidence gate

Ties out

Goes forward for authorisation.

Variance or gap

Held for the indirect-tax reviewer.

Reviewer authorisation

The package is held with its workpapers, tie-out, certificate coverage and confidence.

Authorise · Adjust · Escalate

Authorised — handed back▼

6Filing package handed overAn authorised person submits and pays; the agent attaches the confirmation to the workpapers

7Outcome evaluatedTie-out variance, taxability accuracy, certificate coverage, on-time filing, notices and amendments

Adjustments

Adjustments and escalations made in review are counted in the evaluation.

What should not run autonomously

Human approval stays in control

Outside the boundary — human approval required8 items

Submitting a return to any filing portal.

Releasing a remittance or approving a payment file.

Registering the business in a new jurisdiction.

Amended returns and refund claims.

Automation boundaryAgent acts unaided

✓Determine taxability, sourcing and rate for each transaction.

✓Apply the registration footprint, certificates and agreed positions.

✓Prepare returns and reconcile them to the general ledger.

✓Route variances and coverage gaps to review with the workpapers.

Returns are submitted and money released only inside the approval boundaries agreed during implementation.

Responses to notices and assessments.

New taxability positions for a product or service.

Accepting a certificate the agent cannot validate.

Changes to rate sources, calendars or thresholds.

Example output

One prepared return, annotated

Everything the agent proposes is attached to the period it was built from.

Prepared return · single periodIllustrative example

Jurisdictions

Taxable sales

Period

Prepared return

Confidence

Ledger tie-out

State, home-rule city

$318,400.00

Monthly

Ready to authorise

91%

Within tolerance

As receivedTaken from the transaction detail for the closed period — nothing here is restated to make it balance.

Evidence used Rate in force at the date Certificate on file Return-to-ledger tie-out

Why two schedulesThe home-rule city taxes a category the state exempts, so each base is prepared apart.

ActionAuthoriseAdjustEscalate

What the score decidesBelow the configured threshold the package is held for review instead of going forward for authorisation.

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

All taxable transactionsFrom billing and the ERP

03Determination

Apply your own footprint

Use the registration footprint, exemption certificates and the taxability positions already agreed.

01Approved path

Cut the preparation and tie-out work

Routine periods come back prepared, reconciled and evidenced instead of being rebuilt by hand each month.

02Human review

Put reviewers on the variances

Unreconciled periods, certificate gaps and new jurisdictions reach a reviewer instead of every return doing so.

04Build an evidence trail

Retain the source detail, rate applied, tie-out, confidence, evaluator result and reviewer decision — on both paths.

Integrations

Typical integrations

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

Transaction sourcesERP · billing · e-commerce
POS · Marketplace feeds

Tax engines & rate dataAvalara · Vertex
Sovos · Rate and boundary files

Certificates & documentsCertificate systems · customer master
Document management · notice files

Agent

Sales-tax & compliance filing

Determines taxability
Prepares and ties out
Holds for authorisation

Filing & remittanceFiling portals · e-file channels
Banking for remittance

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 a filed return

Each control wraps the one inside it. A return clears every layer before anyone is asked to sign it.

L6 · Outermost — last line of defenceInward → L1 · closest to the model

L6Rollback / safe modeRestrict automation if evaluations or production signals degrade.Roll back

L5Version monitoringTrack rate and rule updates, model, prompt and configuration changes.Track

L4TraceabilityRecord source detail, rate applied, tie-out, decision and adjustment.Record

L3Filing authorityDefine who may submit a return and release the remittance.Gate

L2Scope guardrailsRestrict returns to registered jurisdictions, periods and agreed positions.Restrict

L1Tie-out checksPrepared liability must reconcile to the detail and the ledger.Reconcile

Model coreReturn prepared — liability by jurisdiction, schedules, tie-out and confidence

L1 – L2Decide whether the return may stand

L3Decides who may submit and pay

L4 – L5Keep the record and the rates current

L6Pulls automation back when signals degrade

How Nestack evaluates it

Evaluate the full workflow — not only the filed number.

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

Surface — the return the reviewer signs

Depth of coverage ▼

E1Final-output evaluationWas the liability right for that jurisdiction and period?

E2Determination evaluationWere taxability, sourcing and rate correct per transaction?

E3Reconciliation evaluationDoes the return tie to the detail and to the ledger?

E4Escalation calibrationAre variances and certificate gaps actually held back?

E5Slice evaluationHow does performance change across specific filing cohorts?

E6Business outcomeHow many returns were amended, late or drew a notice?

Floor — the outcome the client pays for

Failure modes

Where each failure originates in the agent

Seven failure modes plotted against the five stages of the agent lifecycle.

Agent lifecycleDirection of processing →

01 · Retrieval1 mode

ST-01

Rate applied from the wrong date

A rate change is read from the wrong quarter.

Stage gathersTransactions, sourcing data, certificates and rates

02 · Determination2 modes

ST-02

Sourced to the wrong jurisdiction

Origin used where the state sources to delivery.

ST-03

Exemption claimed without support

A missing or expired certificate reads as valid.

Stage proposesTaxability, rate, jurisdiction and confidence

03 · Tool / write2 modes

ST-04

Filed or paid without authorisation

Submitted or paid before anyone authorised it.

ST-05

Filed to the wrong period

The return lands in a period already closed.

Stage writesOnly where filing authority and approval policy allow

04 · Output1 mode

ST-06

Return does not tie to the ledger

Prepared liability and the ledger disagree.

Stage returnsThe prepared return and its tie-out to the ledger

05 · Change / Version1 mode

ST-07

Nexus or calendar drift

A crossed threshold or a new frequency is missed.

Stage tracksRate updates, calendars, model and configuration

Sev-1 · a filing obligation is breached Sev-2 · wrong liability reaches the return Sev-3 · tie-out fails, package routes to review

See the complete Accounting failure-mode catalogue →

Affected slices

One jurisdiction mix can carry the whole error rate

Single-state monthly filings behave predictably; home-rule cities, exempt sales and newly registered states are where determination and tie-out errors concentrate. Nestack reports performance by slice, not only in total.

Slice performance — reported separately, not only in aggregateIllustrative example

Slice	Failure rate	Lift	Status
Home-rule jurisdictions	5.2%	3.3×	Review
Exempt and resale sales	3.7%	2.4×	Review
Newly registered states	2.8%	1.8×	Watch
Single-state monthly filings	1.0%	0.6×	Normal

Bar: lift vs. single-state baseline · scale 0–4.0× · tick marks the 2.0× review threshold 2 of 4 slices over threshold

Evidence-linked improvement

Rates and certificates go stale on a date

Each cycle ends with a rate source re-dated, a certificate chased or a tie-out rule tightened — and the next period is measured against that.

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

01Detect

Tie-out variance or notices rise in a cohort.

02Diagnose

Traced to a rate source, a sourcing rule, a certificate or the feed.

03Improve

The fix is approved, version-linked and dated from the period it applies.

04Verify

Affected periods are prepared and tied again.

05Learn

That period becomes a standing case in the regression calendar.

Learn → DetectThe return edge. The next period starts with one more dated rule and one more re-tied case.

Typical build scope

Twelve workstreams across six weeks

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

Workstream Week 1Week 2Week 3Week 4Week 5Week 6

01Workflow discovery and filing-authority definition.

02Registration footprint and filing calendars.

03Source-system and tax-engine assessment.

04Transaction ingestion and sourcing data.

05Taxability, sourcing and rate-date logic.

06Certificate matching and coverage checks.

07Return preparation and ledger tie-out.

08Filing-portal and remittance integration.

09Evaluation suite and regression periods.

10Guardrails and filing-authorisation controls.

11Observability and trace 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 state and its locals ProductionProduction filing cycle AdvancedMulti-state and home rule

Introduced at Pilot

Return preparation and tie-out✓✓✓

Human authorisation before filing✓✓✓

Baseline evaluation✓✓✓

Introduced at Production

Client taxability positions—✓✓

Exemption-certificate checks—✓✓

Authorised filing packages—✓✓

Observability and evaluation—✓✓

Introduced at Advanced

Home-rule and local schedules——✓

Nexus and calendar monitoring——✓

Multi-entity, high volume——✓

Enterprise controls——✓

Build price From $5,000 From $8,000 Custom quote

Final build priceConfirmed after discovery based on jurisdictions in scope, transaction volume, certificate coverage, filing 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 registrations, filing calendars and portal access → Registration footprint and filing-calendar mappingWeek 1

02Who may submit a return and release the remittance → Filing-authority definition and authorisation controlsWeek 1

03Access to the ERP, billing and marketplace transaction data → Source-system and tax-engine assessment, then ingestionWeek 2

04Your agreed taxability positions by product and service → Taxability, sourcing and rate effective-date logicWeek 3

05Exemption certificates and the customers they cover → Certificate matching, coverage checks and expiry handlingWeek 3

06Recent returns, notices and any amended filings → Evaluation suite, regression periods and failure-mode testingWeek 4

07Named reviewers or test users → Authorisation workflow, then the pilot filing cycle and 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. Week 5 runs evaluation and the first supervised filing cycle together.

Phase W1W2W3W4W5W6

Discovery W1

Build W2 – W3

Evaluate W4 – W5

Pilot & Launch W5 – W6

Week focus W1Workflow discovery, filing authority and registration footprint W2Transaction ingestion, engine access and the determination baseline W3Taxability and sourcing logic, certificates and the ledger tie-out W4Evaluation suite, authorisation guardrails and failure-mode testing W5Portal and remittance integration, then a supervised filing cycle W6One live period filed under authorisation, then Agent Care handover

Reading the bandBars cover only the weeks their work is named in. Nothing is filed before week 5, and only under authorisation.

At the end of W6One live period is prepared, tied out, authorised and filed by your team, then Agent Care monitors.

DurationSix-week plan shown · typical delivery 4–6 weeks depending on scope confirmed in discovery.

Next step · Accounting AI agent

Build a sales-tax filing agent around your compliance calendar.

Show us your registrations, transaction sources and who signs the returns. We'll work back from the authorisation point, agree what can be prepared unattended and scope a pilot on one filing period.

Discuss this agent →

Nestack Agents · Sales-tax & compliance filingAGT-ACC-07 · Agent Care available after launch