Is an electronic signature required on e-invoice?
Short answer
No. Where e-invoice is delivered through the Peppol network, neither a qualified electronic signature nor a qualified electronic seal is required. For an e-invoice delivered outside Peppol, a signature or seal may be used as one method of ensuring authenticity of origin and integrity of content under § 71 ods. 3 písm. b) of the VAT Act, but it is not mandatory for every e-invoice.
Not a generic replacement
Not every e-invoice must have a qualified signature.
Delivery service
The secure channel and the identity of the providers are part of the provability.
Control bond
Logs, statuses, versions and patches are important.
Content of the document
The signature will not correct wrong amounts, VAT numbers or missing fields.
Detailed explanation
When it comes to e-invoicing, the concept of evidential value is often confused with that of a signature. An electronic signature may be one of the tools, but modern electronic invoicing relies primarily on a structured document, secure transmission, identification of the parties involved, validation rules and an audit trail. A company must be able to prove who issued the invoice, what it contained, how it was delivered and that it was not altered after issuance without a record of such changes.
As set out in the law and technical rules
The Financial Administration’s FAQ distinguishes between an e-invoice delivered via Peppol, for which neither a KEP nor a K-EP seal is required, and delivery outside the Peppol network, for which a signature or seal is one of the options under Section 71(3)(b) of the VAT Act. From 1 July 2030, the wording of the Act will be clarified to specify a qualified electronic signature or a qualified electronic seal.
Practical examples
- The invoice is delivered via a certified courier, and the company retains the XML file, delivery status and internal approval.
- The partner contractually requires the attachment to be signed. This is a specific business requirement, not a general rule for every e-invoice.
- If the XML file is overwritten after dispatch without a record being made, neither the signature nor the PDF preview will resolve the compromised audit trail.
Common misconceptions
- “Without a signature, an e-invoice is invalid.” Not generally speaking. Evidential value can also be ensured by other checks.
- “A signature is sufficient in place of validation.” No. The XML must be correct in terms of both content and technical format.
- “The PDF signs the invoice, so the XML isn’t needed.” No. A mandatory e-invoice is a structured document.
Conclusion
An electronic signature may be an additional assurance method, but it is not a general requirement for e-invoice delivered through Peppol.
Legal and technical basis
- Act No. 222/2004 Coll. on VAT, rules on authenticity of origin, integrity of content and legibility
- Act No. 222/2004 Coll. on VAT, Section 76a
- Act No. 431/2002 Coll. on accounting
- OpenPeppol eDelivery rules
Related questions
This does not constitute legal advice. Sources: Financial Administration FAQ 9/DPH/2025/IM, example no. 68 and technical example no. 13; VAT Act, Section 71(3) letters b). Verified on 13 July 2026.
Official cases from the Slovak Financial Administration’s FAQs
The following questions and answers are taken from the current July FAQ from the Financial Administration and have been assigned to this topic. Grouping the cases prevents the creation of duplicate pages, whilst retaining the full answer and the exact wording of the question.
Example No. 2: Ensuring the authenticity and integrity of an e-invoice (without an electronic signature): How will the authenticity of the document be ensured, given that it will not be electronically signed? Apart from the fact that, once sent, the accounting system will lock it after issuance to prevent any compromise of its authenticity? Will this be handled as part of the ‘security’ measures by the postal service providers?
The authenticity and integrity of the document are ensured by a combination of procedural and technical mechanisms within the Peppol network, in particular through the use of the secure AS4 communication protocol, the trustworthiness of the message brokers, unique document identification (UUID), the Message Level Status (MLS) mechanism, and internal controls within the accounting system (e.g. locking the document after dispatch). A document-level electronic signature is not required in this model.
Example No. 13: Ensuring integrity and authenticity (KEP/K-EPeč): Will invoices transmitted in G2G (or B2G) mode be required to be signed with a qualified electronic seal (K-EPeč) or a qualified electronic signature (KEP)? Or is it considered sufficient if the integrity of the content and authentication of the origin are ensured by the transmission technology itself (e.g. an encrypted channel between certified access points and a reliable audit trail), or will an additional element of electronic document authorisation be required by law?
No. If an e-invoice is delivered via the Peppol network, neither a qualified electronic signature (KEP) nor a qualified electronic seal (K-EPečať) is required. The authenticity of origin, integrity of content and secure transmission of e-invoices are ensured on the Peppol network through a combination of procedural and technical mechanisms, in particular the secure AS4 communication protocol, the trustworthiness of certified delivery service providers (e-invoicing delivery-service providers), unique document identification (UUID), the Message Level Status (MLS) mechanism, and internal controls within the accounting system. If an e-invoice is delivered outside the Peppol network (for example, by agreement between the supplier and the customer), a qualified electronic signature or a qualified electronic seal may be used to ensure the authenticity of origin and the integrity of the XML file’s content, in accordance with Section 71(3)(b) of the VAT Act. A qualified electronic signature or a qualified electronic seal is therefore one of the possible ways of securing an electronic invoice outside the Peppol network, but it is not a requirement when delivering it via the Peppol network.
Primary source: Financial Administration of the Slovak Republic, FAQ 9/VAT/2025/IM k e-invoice, July 2026 update. Processed and checked on 13 July 2026.