Raw UBL XML

Raw XML is a first-class input. Send a complete UBL 2.1/HR-CIUS Invoice or CreditNote, not a Tax Administration FIS request.

Direct XML

POST /public/v1/outgoing-invoices HTTP/1.1
Authorization: Bearer TOKEN
Content-Type: application/ubl+xml
Idempotency-Key: erp-ubl-2026-000001
IIProxy-Auto-Issue: true
IIProxy-Delivery-Channel: AS4

<?xml version="1.0" encoding="UTF-8"?>
<Invoice xmlns="urn:oasis:names:specification:ubl:schema:xsd:Invoice-2">...</Invoice>

Supported content types are application/xml, text/xml, and application/ubl+xml. Automatic issuance also requires invoices:issue.

JSON envelope

Use the envelope when XML needs explicit advance applications or control options.

{"format":"UBL","ublXml":"<?xml version=\"1.0\"?><Invoice ...>...</Invoice>","deliveryChannel":"AS4","advanceApplications":[{"sourceInvoiceId":"...","amount":100}],"issue":true}

Validation and preservation

Klik Račun rejects DTD and entity declarations, extracts standalone UBL from SBDH, checks supplier and operator ownership, validates exchange and fiscalization rules, verifies that amounts can be projected safely, and preserves the P1–P12 process classification.

It stores the standalone XML and its SHA-256 digest. Issuance does not regenerate raw XML from JSON. The only permitted enrichment is deterministic insertion of missing, system-managed BG-3 references required by the guarded advance flow. Download the effective document from /extract-xml/ubl.

Corrections use a guarded flow

The general create route rejects P10 and InvoiceTypeCode 384. Submit that XML through the correction preview and confirmation flow, where Klik Račun verifies the chain, reference, and source version.