Merlin ERP and e-Invoicing in 2026: integration options, frequent errors, solutions
Merlin ERP does not include a native e-invoicing connector in the standard license, requiring a partner or custom development. Complete guide for integration with ANAF (the Romanian tax authority), top 10 CIUS-RO errors, and the Smart Layer solution.
Bogdan Minoiu — Founder Azuvio · 2026-08-12 · 10 min · Reglementări
e-Invoicing Status in Merlin ERP
Prodigy Software has delivered e-invoicing support through add-on modules, rather than including it in the core license. There are three integration options:
1. Official Prodigy Module: developed by the internal team, delivered as a paid add-on (~€2,000-€4,000 initially + annual maintenance). It covers CIUS-RO XML generation, digital signature, submission to the tax authority, and receiving status updates.
2. Integration Partners: certain local providers offer e-invoicing connectors for Merlin. Cost: €1,200-€3,500/year.
3. Azuvio Smart Layer: includes the e-invoicing module at no extra cost, featuring CIUS-RO validation and automatic retry logic.
Typical e-Invoicing Workflow
1. The invoice is issued in Merlin (standard form)
2. The system generates the CIUS-RO XML (mapping Merlin fields → official schema)
3. XML is signed with a digital certificate
4. Sent to the tax authority (ANAF) via official API
5. Response received (accepted / rejected / errors)
6. Status saved back into Merlin on the invoice record
Top 10 Common CIUS-RO Errors
1. Invalid Supplier VAT ID or missing prefix — automatic verification must be implemented.
2. Incorrect VAT codes — VAT 19% vs 9% vs 5% vs exemptions — incorrect mapping in Merlin.
3. Non-standard unit of measure — CIUS-RO requires UNECE codes (PCE, KGM, etc.), while Merlin allows free text.
4. Missing CPV code — mandatory for transactions with public institutions (B2G).
5. Amounts without 2 decimals — local formats (comma vs point) cause rejections.
6. Incomplete address — region + postal code + country are mandatory.
7. Duplicate Invoice ID — Merlin may allow number reuse, the tax authority does not.
8. Missing exchange rate — for invoices in other currencies, the official central bank rate for the issue date is mandatory.
9. Missing attachments for prepayments — advance invoices require contract references.
10. Expired digital signature — certificates must be renewed annually.
The Azuvio Smart Layer Solution
Azuvio Smart Layer intercepts the invoice from Merlin, validates all 10 points above before submission, generates the compliant CIUS-RO XML, signs, submits to the tax authority, and saves the response in Merlin via API.
Advantages:
Zero modifications in Merlin (zero risk for the ERP)
Pre-submission validation (rejection rates <1% vs an average of 8-12%)
Automatic retry for temporary tax authority downtime
Centralized dashboard (all invoices, all statuses)
Cost: included in the Smart Layer subscription
Comparative Cost
| Option | Year 1 Cost | Maintenance | Note |
|---------|-----------|------------|------|
| Prodigy Module | €2,500-€4,000 | €600/year | Requires Merlin upgrades |
| Integration Partner | €1,500 | €1,200/year | Variable quality |
| Azuvio Smart Layer | included | included | Pre-submission validation |
Conclusion
For e-invoicing, Azuvio Smart Layer offers the best combination of cost + risk + UX. If you already have the Prodigy module and it works stably, keep it. If you are still looking for a solution or facing high rejection rates — Smart Layer is the pragmatic choice.
See also «SAF-T D406 in Merlin».