What is it? XSD validation?
Short answer
XSD validation is a technical check of an electronic invoice. Checks that it is XML the invoice correctly created and whether other systems can read it correctly. Simply put: XSD check that the electronic invoice is correctly folded. However, it does not verify whether the data on the invoice is correct on a commercial or accounting basis.
Basic condition
Before XSD must be XML not at all well-formed, correctly closed tags, namespace, quotation marks, one root element.
Structure, not just order
Obligation of occurrence, frequency, data types, order and permitted location of the element by UBL 2. 1 XSD.
Business logic
XSD Doesn't know if the sum fits VAT, BuyerReference or rules EN 16931/Peppol BIS/Slovak transposition is used for this Schematron.
No custom XSD
Peppol BIS Billing 3.0 nublis its own XSD It's CIUS over EN 16931using the existing syntactical basis of OASIS UBL 2.1.
Conclusion
Financial Administration of the Slovak Republic, FAQ 9/VAT/2025/IM k e-invoice, July 2026 update
Not legal advice. Machine-translated answer, not yet manually reviewed. For the exact wording, see the Slovak original.