Diia.Signature-EU: Legal Aspects of Using the Ukrainian Electronic Signature in the EU

As digital technologies continue to evolve, the use of Ukrainian electronic signatures within the European Union has become an increasingly relevant topic. Specifically for use within the EU, the Diia app introduced the Diia.Signature-EU format, which allows documents to be signed with legal effect across the territory of the European Union.

The Legal Status of Diia.Signature-EU in the EU

In Ukraine, a qualified electronic signature is equivalent to a handwritten signature and carries full legal effect. In the European Union, however, a standard Ukrainian electronic signature issued through Diia is treated as an Advanced Electronic Signature (AdES).

The Diia.Signature-EU format was specifically designed to meet European standards and is likewise recognised in the EU as an Advanced Electronic Signature (AdES). A document signed this way has legal effect, ensures data integrity, contains a timestamp, and allows the signatory to be identified. However, an advanced electronic signature does not carry an automatic presumption of authenticity and is not equivalent to a handwritten signature — a status reserved for the EU’s Qualified Electronic Signature (QES).

Current State of Mutual Recognition

At present, there is no comprehensive agreement between Ukraine and the European Union providing for EU-wide mutual recognition of qualified electronic signatures. Ukraine became the first non-European country whose trust services were included in the European Commission’s special list — the TC AdES LOTL (Third Countries Trusted List). This allows Ukrainian advanced electronic signatures to be technically verified in EU member states, though it does not automatically grant them qualified electronic signature status.

According to public statements by Valeriya Ionan, former Deputy Minister of Digital Transformation of Ukraine, if Ukraine successfully implements the plan set out in the updated Joint Roadmap, certain Ukrainian electronic signatures, seals, and other trust services could be recognised in the EU as early as 2026, with full mutual recognition of all Ukrainian electronic identification and trust services expected by 2027.

The updated roadmap envisages several key steps:

• Assessing the compliance of Ukrainian legislation with EU standards, including eIDAS, NIS2, and GDPR requirements;
• Establishing cooperation procedures between Ukraine and the European Commission;
• Testing the cross-border interoperability of trust services;
• Verifying bilateral cooperation mechanisms.

European countries apply different electronic signature formats, each choosing the option best suited to its needs. The Baltic states — Estonia, Latvia, and Lithuania — actively use the XAdES format combined with the ASiC-E container. In Austria, Poland, and Italy, the PAdES format is more commonly used for PDF documents.

All of these standards — PAdES, CAdES, and XAdES — are now available within Diia.Signature. They are compatible with European services and require no additional configuration.

An Important Precedent — Latvia

In February 2026, Latvia became the first European Union country to introduce national-level mutual recognition of Ukrainian qualified electronic signatures. Such signatures, including Diia.Signature-EU, are now recognised in Latvia as equivalent to a handwritten signature. This decision demonstrates that bilateral arrangements can be implemented faster than an EU-wide agreement.

Practical Application in the EU

Within the European Union, public authorities and institutions are not always willing to accept an advanced electronic signature, since it does not qualify as an EU Qualified Electronic Signature. An EU Qualified Electronic Signature is equivalent to a handwritten signature and carries the maximum legal effect.

As a result, institutions may either accept or refuse documents signed with Diia.Signature-EU, depending on the field of application, the nature of the document, and internal requirements. For documents with significant legal consequences, an EU Qualified Electronic Signature is typically required.

Full, automatic recognition of Ukrainian qualified electronic signatures as equivalent to an EU QES across the entire European Union is still a work in progress, although positive momentum is visible, including at the level of individual EU member states.

If you need assistance with the legal aspects of using electronic signatures in Lithuania or elsewhere in the EU, the Legal Mechanic team is ready to advise you.