An invoice may arrive as a scanned PDF, a photograph, or an email attachment. Getting the total into a spreadsheet is only one step: your team still needs to check the supplier, tax, duplicate status, and purchase order. This guide follows that process from receipt to an approved record.
AI can help when supplier layouts vary or line items are difficult to capture with fixed templates. It should not be the authority that decides whether money is owed. Financial approvals, supplier identity, duplicate checks, totals, tax treatment, and posting rules still require deterministic controls and accountable people.
Related service: AI document and workflow automation- 01Capture the file and record its source, time, and checksum.
- 02Classify the document or route it to an unknown queue.
- 03Extract candidate fields and line items with provenance.
- 04Validate totals, suppliers, references, duplicates, and required fields.
- 05Resolve exceptions with the source document visible.
- 06Obtain approval and post the record once to the ERP.
- 07Monitor failures and reconcile the posted record with the source.
SECTION 01
Map the manual invoice flow first
Follow several real invoices from arrival to final posting. Record every inbox, upload folder, spreadsheet, approval, accounting screen, and person involved. Pay special attention to exceptions: a new supplier, a missing purchase order, a duplicated invoice number, a mismatch between lines and total, a credit note, or an unreadable scan.
The map should also show the source of truth. The email system may receive the document, a document store may preserve it, the ERP may own the payable record, and an approval system may own the decision. An automation that creates a second unofficial record can make reconciliation harder rather than easier.
Trigger
Email attachment, portal upload, scan, shared folder, or system event.
Required data
Supplier, invoice number, dates, currency, purchase reference, totals, taxes, and relevant line items.
Exceptions
Missing or conflicting data, duplicate records, unknown suppliers, failed purchase-order match, or unsupported files.
Completion
Approved record posted once, source retained, status visible, and downstream team notified if required.
SECTION 02
Design a seven-stage target flow
Treat each stage as a separate responsibility with its own input, output, error state, and owner. This makes the system testable and prevents a confident extraction from bypassing a failed business rule.
| Stage | System responsibility | Required control |
|---|---|---|
| 1. Capture | Receive the file and record its source, time, sender, and checksum. | Allow only approved channels and file types; quarantine failures. |
| 2. Classify | Identify invoice, credit note, supporting document, or unknown. | Keep an unknown queue and never force every file into an invoice class. |
| 3. Extract | Produce structured candidate fields and line items from the document. | Retain field-level provenance or location and confidence where available. |
| 4. Validate | Check format, totals, duplicate keys, supplier identity, references, and required fields. | Use fixed rules and current master data. |
| 5. Resolve exceptions | Present the source, failed rule, and proposed value to the right person. | Capture corrections and reasons; do not silently edit the source. |
| 6. Approve | Apply the organization's authority and separation-of-duty process. | A named role approves according to current policy. |
| 7. Post and monitor | Create or update the ERP record once and track the outcome. | Use idempotency, audit logs, reconciliation, alerting, and a recovery path. |
SECTION 03
Worked example: an invoice that must stop for review
Suppose a sample invoice contains two service lines: $600 and $400, with a stated $80 tax line and a stated total of $1,180. The amounts below are invented to demonstrate a consistency check; the tax line is taken from the sample document, not a tax-rate recommendation.
AI may correctly read every field and still produce a record that must not be posted. The arithmetic is $600 + $400 + $80 = $1,080, so the stated total differs by $100. A fixed validation rule should stop this item and show the discrepancy to an accounts-payable reviewer.
| Check | Expected behavior | Evidence retained |
|---|---|---|
| Total does not reconcile | Hold the invoice; do not silently replace $1,180 with $1,080. | Original file, extracted fields, computed sum, and failed rule. |
| Supplier correction arrives | Link the corrected document and ask the authorized reviewer to approve it. | Both versions and the review decision. |
| Posting request times out | Check the destination record using the stable invoice key before retrying. | Request key, attempt time, and any returned ERP identifier. |
| Same file arrives again | Identify the duplicate and show the existing processing status. | Original invoice identity and duplicate event. |
SECTION 04
Keep extraction and validation separate
An extracted value can look plausible and still be wrong. The supplier name may resemble a known supplier, the total may parse correctly while line items do not reconcile, or the invoice number may duplicate a record under another file name. Extraction answers what appears to be on the document; validation answers whether the candidate record is acceptable to the business.
Validation rules should be versioned and observable. If a rule changes, the team should be able to tell which invoices were evaluated under which version. A manual correction is valuable operational data: repeated corrections may reveal a supplier layout issue, a weak prompt, missing master data, or a rule that does not match the real process.
SECTION 05
Make exceptions and approval auditable
An exception interface should show the original document beside the extracted fields, highlight the failed rule, and provide the information needed to resolve it. The reviewer should not have to search across several systems to understand why the item stopped.
Record who changed a value, what changed, why it changed, when approval occurred, and what was posted. Restrict access by role, protect sensitive supplier and financial data in storage and transit, and decide how long documents and logs are retained according to the organization's legal and operational requirements.
SECTION 06
Integrate with the ERP as a recoverable transaction
Use an API or supported integration path where possible. Give each invoice a stable idempotency key so a retry does not create a second payable record. Save the external record identifier and the response needed for reconciliation. If posting fails after approval, keep the item in a visible retry queue rather than treating the workflow as complete.
Test authentication expiration, rate limits, validation errors, unavailable endpoints, partial line-item failures, and network interruption. The operational team needs a documented manual path when the integration is unavailable and a clear way to reconcile records after service returns.
- 01
Define the ERP fields, reference data, and validation rules required for a valid payable record.
- 02
Choose the stable key that prevents duplicate posting across retries.
- 03
Separate approved-but-not-posted items from unapproved exceptions.
- 04
Log request state without exposing credentials or unnecessary invoice data.
- 05
Reconcile successful postings and investigate unmatched items on a defined schedule.
SECTION 07
Estimate operational ROI without inventing savings
Collect a representative sample and measure active handling time before automation. Then run the proposed workflow in parallel and measure human review time, exception rate, correction time, support effort, and system cost. Do not count queue time as staff time unless reducing that delay has an identified business value.
A transparent starting formula is: monthly handling hours saved = invoice volume × (average active minutes before − average active minutes after) ÷ 60. From that result subtract monitoring, exception handling, maintenance, vendor, hosting, and integration costs. Use a range when volume or exception rate varies.
| Measure | Baseline | Pilot | Decision question |
|---|---|---|---|
| Invoices processed | Count by channel and supplier type | Same representative mix | Was the comparison like-for-like? |
| Active handling minutes | Observed median and range | Review plus exception time | Did staff effort actually fall? |
| Correction rate | Manual correction sample | Field and rule corrections | Which errors remain material? |
| Cycle time | Arrival to approved posting | Arrival to approved posting | Did queues or approvals improve? |
| Operating cost | Current labor and system cost | Technology, review, and maintenance | Is the total process worth operating? |
SECTION 08
Use a release checklist before live posting
Start with shadow processing or a non-production destination. Compare extracted and validated records with the existing process, test the most consequential exceptions, and require explicit sign-off from the finance and system owners before enabling live posting.
PRIMARY REFERENCES
Sources and further reading
These references cover the standards, platforms, or published prices discussed in the guide. Worked examples and checklists are our editorial guidance.
- AI Risk Management FrameworkNational Institute of Standards and Technology
EDITORIAL METHOD
About this guide
We use AI to assist with drafting and editing. Catapult AI Work is responsible for the published content. Examples illustrate possible approaches; they are not client case studies unless identified as such.
Budget examples are not Catapult package prices. Check linked provider pages for current fees and plan limits before making a purchase.
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