The short answer
Place invoice files in a restricted intake folder. n8n records the document, extracts available text or calls an approved OCR service, and validates candidate fields. Store the source and proposed values in a review queue. Only an authorised reviewer can approve export to the accounting system.
The connected workflow
Reference design · Proposed steps to validate in a pilot, not a deployed customer case study.
- Document received
Record the file ID, version and processing status.
- Text extracted
Read text-based PDFs or route scanned files to an approved OCR service.
- Fields checked
Validate supplier, invoice reference, currency, dates and totals.
- Duplicates flagged
Compare the document and supplier invoice reference against existing records.
- Person reviews
Present the original alongside candidate values and unresolved checks.
- Approved record exported
Write through the accounting system’s supported interface and retain its record ID.
What each tool does
- Google Drive
- Restricted intake and original document storage.
n8n + extraction service- Coordinates file handling, parsing and validation. Scanned documents need suitable OCR.
- Google Sheets / review system
- A limited pilot queue with document references and review status.
- Accounting team
- Resolves mismatches and approves the final accounting record.
Keep the original
Use one restricted intake route and retain the original document with a stable ID. Define accepted formats and file sizes. A changed file version should create a new review event, not silently change an approved invoice. Reject unreadable or unexpected files into a visible exception queue.
Choose the extraction route
The n8n Extract From File node supports extracting data from several file types, including PDFs. A scanned image may need a separate OCR service. Test both against your actual document formats. Treat the extracted fields as candidates; a fluent model response is not a verified accounting record.
Validate before review
Use explicit currency codes and parse dates according to the supplier context. Check that line amounts and taxes reconcile to the stated total within a defined rounding rule. Flag missing supplier information or ambiguous invoice references. Keep the source text or page reference with each field so the reviewer can check it.
Catch duplicates carefully
A file hash can catch the same document, while a supplier ID and invoice reference can catch a second scan. Neither check should automatically discard an ambiguous record. Credit notes, reissued invoices and shared references need review. Retain the reason for every duplicate flag.
Separate review from payment
A spreadsheet can support a small pilot, but approval identity, concurrent edits and access must be controlled. Use an authenticated approval step for the final decision. The workflow prepares a record; it does not authorise payments or change supplier bank details. Those actions stay in the established finance process.
Prove the export
Test a scan, a multi-page invoice, a missing currency, a duplicate, a corrected document and an accounting API timeout. If export may have succeeded, look for the external reference before retrying. Measure field corrections, blocked documents and duplicate exports separately.
Common questions
Can it read every PDF?
No. Text PDFs, scans and unusual layouts need different handling. Test a representative sample and keep a manual route for unsupported documents.
Will it pay invoices automatically?
No. This reference design ends with a reviewed accounting record. Payment authorisation remains in your existing finance process.
Sources & scope
Provider documentation checked on 20 October 2026. The workflow is our proposed implementation design; platform features, plans and integrations must be confirmed for your project.
Your next step
Share the document formats, monthly volume and accounting tool—without confidential invoices. We can scope an intake pilot around the checks your finance team already uses.
Explore the related solution