Partner Transaction API

The Partner Transaction API lets an ERP partner send its clients' sales and purchase invoices and credit notes to VAT IT for VAT return preparation and filing, and read back the status, errors and filing state of every line.

Key rules:

• One record is one document: an invoice or credit note, with its lines nested inside it.
• Resending is always safe. A document is keyed by client_ref and document_id, and ordered by source_updated_at, the time it last changed in your ERP.
• A newer source_updated_at replaces the whole document. You never send a delta.
• A credit note is a document of its own. It never voids or replaces the invoice it credits.
• Documents are acknowledged in seconds and checked in the next scheduled processing cycle. Sending as invoices are raised and sending after month-end close both work, through the same endpoint.
• Every problem is a stable code plus the field it concerns. Show your users your own text, keyed by code.
• A line's tax code is a VAT IT tax code, or your own code where VAT IT keeps the mapping for that client.
• Sending is the only part you must build. The read endpoints are optional; without them, VAT IT works through any errors found after arrival with the client directly.