---
updatedAt: 2026-08-19T14:45:32.000Z
agentTools:
  projectIndex: https://ae.docs.digitax.tech/llms.txt
---

# Self-billed invoices calculations and validations

* Requires `supplier_id` (enforced indirectly: without it, `389` fails the regular `IsValidInvoiceType()` check).
* The branch must have company details and a postal address configured.
* Otherwise shares all core invoice validation and calculation rules above.