Vendor Invoice Management: How Supplier Invoices Reach Your ERP

Manual keying

A person reads the PDF and types the fields. Accuracy depends entirely on attention, and the cost per invoice is flat: it never improves with volume. Workable below roughly 20 invoices a month, painful above it.

OCR and AI extraction

Software reads the PDF and predicts the fields. It is a genuine improvement over typing, and it is the only option for suppliers who will never send structured data. The catch is that a prediction needs a confidence threshold and a review queue. Layout changes at the supplier side, credit notes and multi-page line items are the usual failure cases, so you keep a human in the loop for exceptions.

Step 1: register the receiving address

Your company is published in the Peppol directory under an identifier, in Belgium normally the enterprise number under scheme 0208. Suppliers look it up and route to it. You do this once.

Step 2: subscribe to the webhook

An incoming document triggers a call to your endpoint. Your handler should acknowledge fast and process asynchronously, store the document identifier for idempotency, and treat a repeated delivery of the same identifier as a no-op. Retries happen. Build for them.

Step 3: map the fields once

The e-invoice.be API returns flat fields, so the mapping to an AP entry is direct. A received document looks like this:

{
  "document_type": "INVOICE",
  "invoice_id": "2026-00417",
  "invoice_date": "2026-09-02",
  "due_date": "2026-10-02",
  "vendor_name": "Depot Materiaal BV",
  "vendor_tax_id": "BE0123456789",
  "vendor_address": "Nijverheidslaan 12, 9000 Gent",
  "customer_name": "Your Company NV",
  "customer_tax_id": "BE0987654321",
  "customer_peppol_id": "0208:0987654321",
  "currency": "EUR",
  "items": [
    {
      "description": "Steel profile 40x40",
      "quantity": 25,
      "unit_price": 18.4,
      "tax_rate": 21
    }
  ]
}

The fields that matter for booking are vendor_tax_id to resolve the supplier record, invoice_id combined with the supplier to block duplicates, due_date to drive the payment run, and tax_rate per line to post VAT correctly. document_type tells you whether you are booking an invoice or a CREDIT_NOTE, which is a common thing to forget on a first integration.

Step 4: decide what happens to unknown suppliers

The first real integration bug in every project is an invoice from a supplier that does not exist in the ERP master data. Do not auto-create. Route it to a review queue, because a new supplier record with a bank account attached is exactly the thing invoice fraud targets.

Option A: dashboard as the AP inbox

Register, get the Peppol ID, and let vendor e-invoices land in the dashboard. Review them there and export to your accounting software as UBL, CSV or PDF. No development work.

• Account creation is instant. Company verification takes 24 to 48 hours, because we check a wire transfer. Everyone registered is a verified business.
• Receiving works the same week

Option B: API integration into the ERP

Wire the webhook into your ERP or middleware so invoices are booked without a human touching them. This is the route for anyone above a few hundred invoices a month.

• Typically a few days of development for the webhook, the field mapping and the duplicate check
• Add time for testing against real supplier documents, which is where format surprises show up

The part that actually takes months

Neither of the above is the long pole. Supplier coverage and internal approval rules are. Expect to spend weeks agreeing approval thresholds and cost centre defaults, and longer getting foreign suppliers onto the network. Keep a PDF conversion path for the ones who will not move. Sequence it by spend: onboard the twenty suppliers who send eighty percent of your invoice volume first, and leave the tail for later.