Updated 8 October 2026 · SimplyX implementation guidance
The implementation process
This checklist is for finance and IT teams working together. For both Hungarian companies with an international background and foreign VAT-registered businesses, setup starts with the reportable invoice scope and the data available from your ERP.
1. Invoice workflow
- Record the issuing entity, Hungarian tax number and invoice types.
- Confirm the reporting scope with your tax adviser.
- Agree with IT when invoice data is final and how corrections are delivered.
2. Access and sample data
- Prepare Online Invoice registration and a technical user for the correct taxpayer.
- Agree the API or SFTP connection and provide anonymised sample invoices.
- Confirm whether NAV XML is available. We arrange a separate secure channel for production credentials.
3. Mapping and feedback
We agree source fields, conversion rules and invoice references. We define how repeat requests are handled, how NAV results are retrieved and where invoices needing correction appear. Assign an owner for each type of failure.
4. Joint testing
- Test ordinary invoices, corrections and cancellations.
- Include the currencies and tax treatments you use.
- Check handling of missing data, rejection and connectivity failures.
- Keep the actual NAV response alongside the expected result; finance and IT should review together.
5. Launch and support
Before launch, we agree checks for the first submissions, monitoring of incomplete reports and the escalation route. The service agreement records support availability, response commitments and how changes to NAV requirements are handled.
Questions before implementation
What is needed for an initial integration enquiry?
The ERP name and version, Hungarian VAT-registration stage, expected invoice volume and available source format provide the starting point. Live credentials are not needed for the initial enquiry.
Does successful testing mean every future invoice will be accepted?
No. Production data and transactions may differ. Status monitoring, correction ownership and an agreed operating process are needed after go-live.
Sources
The steps above are SimplyX implementation guidance. The official NAV interface documentation defines the technical requirements.
Related guides
Send your ERP name, VAT-registration stage, invoice volume and source format.