Has e-invoice contain the QR code?
Short answer
No. Slovak legislation and standards EN 16931 a Peppol BIS Billing does not currently generally require electronic invoices to contain QR code.
Not a substitute XML
QR code will not save an invoice that has bad amounts, identifiers or non-validated structure.
Practical use
Most often it bears payment data so that the customer does not have to overwrite IBAN, variable symbol and amount.
For people, not for the core
QR code may refer to preview or payment, but accounting import should read structured fields.
Data must fit
If QR contains an amount or an account, it must be consistent with XML and accounting documents.
Conclusion
QR code can be a useful complement to an electronic invoice, especially when paying or displaying a document.
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.