UBL vs ISDOC — a comparison of electronic invoice formats
UBL 2.1 and ISDOC are the two main electronic invoice formats in Central Europe. We compare their advantages, disadvantages and use.
For the obligation from 2027 you need UBL 2.1 (EN 16931) through the Peppol network — the Czech ISDOC is not enough to comply with Slovak law. ISDOC only makes sense when your Czech customer or their accounting software requires it. Efakturia exports both formats, so you do not have to choose.
UBL 2.1 (Universal Business Language)
UBL is an international standard maintained by OASIS. Version 2.1 is the basis for the European standard EN 16931 and Peppol BIS 3.0.
- Use: Europe-wide, mandatory for Peppol.
- Format: XML.
- Standard: EN 16931 (the European standard for electronic invoicing).
- Support: broad — SAP, Oracle, Microsoft, most ERP systems.
ISDOC 6.0
ISDOC (Information System DOCument) is the Czech national format for electronic invoices. It was developed by the Czech Association for Electronic Commerce (APEK).
- Use: mainly in the Czech Republic, partly in Slovakia.
- Format: XML.
- Support: Pohoda, FlexiBee, Money S3, Abra.
Comparison
| Feature | UBL 2.1 | ISDOC 6.0 |
|---|---|---|
| International standard | Yes (EU) | No (Czech) |
| Peppol compatible | Yes | No |
| EN 16931 compatible | Yes | Partly |
| Accounting software support | Broad | CZ/SK systems |
| Obligation from 2027 (385/2025) | Compliant | Will not be enough |
Which format to use?
For the obligation from 2027 we recommend UBL 2.1 through the Peppol network (delivered by a certified postman). If the Czech ISDOC is enough for your customers (e.g. for import into Pohoda), efakturia.sk supports export to both formats.
Pohoda XML
Besides UBL and ISDOC, efakturia.sk also supports export to the Pohoda XML format (mServer), which is compatible with Stormware Pohoda — the most widely used accounting software in the Czech Republic and Slovakia.