Does the e-invoice have to contain a QR code or a payment link?
Short answer
Nope. Neither the QR code nor the payment link are mandatory elements of the Slovak e-invoice. The VAT Act does not include a QR code or a payment link among the mandatory invoice data. It does not contain or give a separate business term for QR code or payment URL
Not a replacement for XML
The QR code will not save an invoice that has bad amounts, identifiers or an invalid structure.
Practical use
It most often carries payment data so that the customer does not have to rewrite the IBAN, variable symbol and amount.
For the people, not for the core
A QR code can refer to a preview or a payment, but the accounting import is supposed to read structured fields.
The data must fit
If the QR contains an amount or an account, it must be consistent with the XML and the accounting document.
Conclusion
A QR code can be a useful addition to an electronic invoice, especially when paying or displaying a document.
the VAT Act · FAQ of the Financial Administration of the Slovak Republic · Peppol BIS Billing 3.0 · OpenPeppol eDelivery
Not legal advice. Machine-translated answer, not yet manually reviewed. For the exact wording, see the Slovak original.