01What is an e-invoice?
An e-invoice is a structured electronic document that contains all the elements of a classic invoice but in a machine-readable format (XML) — not as a PDF or scan, but as data that the buyer’s system can post automatically without manual entry.
The EU has standardised the e-invoice under EN 16931 (the semantic model) and the UBL 2.1 format (Universal Business Language). The specific profile for cross-border exchange is Peppol BIS Billing 3.0 — the standard REDOK uses for every outbound invoice.
In Croatia, the EU standard sits alongside the national e-invoice fiscalisation specification (Fiscalisation 2.0, in force from 1 January 2026). REDOK covers both layers in a single pass.
02Croatian Fiscalisation 2.0
From 1 January 2026, every B2B invoice in Croatia must be issued as an e-invoice and reported to the Tax Authority. Legal entities that don’t exchange structured e-invoices after that date risk administrative fines and tax liability.
REDOK acts as the information intermediary towards the Tax Authority:
- We forward the e-invoice for fiscalisation just before delivery to the buyer.
- We receive and store the fiscalisation response (JIR, ZKI, status).
- We validate syntactically and semantically before sending — errors caught at source.
- We archive the original document and the response for at least 11 years, integrity sealed.
The customer only sees a green check — REDOK handles REST calls to the Tax Authority, retry logic, edge cases (Tax Authority down → deferred submission), audit trail and reporting in the background.
03For sellers / For buyers
E-invoicing is a two-way exchange. REDOK covers both sides — outbound invoices (you issue to customers) and inbound (you receive from suppliers).
Outbound e-invoices
You generate the invoice in your ERP — REDOK validates it, signs it electronically, sends it for fiscalisation, and delivers it to the buyer (via Peppol or directly).
- UBL 2.1 / Peppol BIS 3.0
- JIR and ZKI automatic
- Electronic signature (eIDAS)
- PDF attachment for human review
Inbound e-invoices
You receive invoices from suppliers — REDOK validates them against EN 16931, converts them into your ERP format, and delivers for automatic posting.
- Automatic detection of VAT/OIB, seller OIB, amounts
- Match against the purchase order (3-way match)
- Notification of rejected invoices
- 11-year archive with full-text search
04Technical details
Supported formats
- UBL 2.1 — primary outbound format, Peppol BIS Billing 3.0 profile
- CII (Cross Industry Invoice) — UN/CEFACT, ZUGFeRD compatible
- EDIFACT INVOIC D96A/D01B — legacy EDI routes to large retailers
- e-Faktura.hr XML — Croatian national profile
- PDF/A-3 with embedded XML — hybrid format for human + machine review
Validation
Before an e-invoice leaves the REDOK network, it goes through four validation layers:
- Syntactic — XML schema validation
- Semantic — EN 16931 business rules (BR-01 through BR-66)
- Profile-specific — Peppol BIS BR-PEPPOL-, or Croatian BR-CO-
- Customer-specific — custom business rules by agreement
Signing and archive
Every outbound e-invoice is signed with a qualified electronic signature (eIDAS), with a time stamp (TSA), and stored in the e-archive that guarantees integrity through a SHA-256 hash chain. Statutory retention is 11 years; many customers keep documents longer for internal purposes.
05Pricing
Two models — pick what fits
- Super Offer — €12 / month for 16 invoices (HR/B2B). Ideal for small and medium businesses that know their monthly volume.
- Prepaid — from €0.07 per invoice, no monthly subscription. Pay only what you use. Ideal for seasonal business or pilot integrations.
The price includes fiscalisation, sending, receiving, archive, helpdesk and updates in line with regulation. For enterprise volumes (10,000+ invoices monthly) and custom integrations we have a separate price list — contact us for a tailored quote.
06Frequently asked questions
Do I need REDOK if my ERP already supports e-invoices?
Not strictly, but most ERPs only generate the XML — they don’t fiscalise it with the Tax Authority, don’t sign with eIDAS, don’t archive in line with the law and don’t forward via Peppol. REDOK is the layer that solves all of this in a single pass, without touching your ERP.
Do I need a certificate for fiscalisation?
Yes — for fiscalisation the Tax Authority requires a FINA (or other qualified issuer) digital certificate. REDOK can mediate the issuance and manage the certificate on your behalf.
What if the Tax Authority doesn’t respond?
REDOK retries in line with the law (up to 8 days of deferred submission). We deliver the invoice to the buyer with a provisional status until the JIR arrives; the customer can issue the invoice even before fiscalisation, as the regulation permits.
Can I send e-invoices abroad?
Yes — via the Peppol network you send to 30+ EU/EEA countries that are on Peppol. For non-EU partners we use other routes (DBNA, partner networks). Every recipient receives the invoice in their local format.
What does onboarding look like?
A typical onboarding is 5-10 business days: (1) contract and certificate, (2) technical connection to your ERP, (3) test messages, (4) UAT with real invoices, (5) go-live. We have ready-made connectors for every major Croatian ERP.
What if I decide to leave?
Within 30 days we export your entire archive in UBL/XML format (and optionally a PDF/A-3 bundle) free of charge. Your data is always yours.