SES or QES? Choosing an Electronic Signature Under eIDAS
Understand how SES and QES differ under eIDAS, when each fits, and how to separate legal requirements from WQ3 signing levels.
1. SES and QES: what the terms mean
The EU’s eIDAS framework distinguishes electronic signatures, advanced electronic signatures and qualified electronic signatures. “Simple electronic signature” (SES) is common shorthand for the basic category, rather than a separately defined legal term. This article focuses on SES and QES, but the advanced category sits between them.
An SES can include typing a name or drawing a signature electronically, provided the electronic data is attached to or logically associated with other electronic data and used by the signer to sign. Its appearance alone does not determine the strength of the evidence behind it.
A qualified electronic signature (QES) is an advanced electronic signature created using a qualified electronic signature creation device and based on a qualified certificate for electronic signatures. That certificate is issued by a qualified trust service provider. QES status depends on these requirements—not on a signature looking official or a platform describing its workflow as secure.
2. The legal difference is more than identity checking
Under eIDAS, an electronic signature cannot be denied legal effect or admissibility as evidence solely because it is electronic or does not meet QES requirements. An SES therefore is not automatically invalid or unusable as evidence. Its evidential weight depends on the signing circumstances and supporting records.
A QES has the equivalent legal effect of a handwritten signature under eIDAS. A QES based on a qualified certificate issued in one EU Member State is recognised as a QES in the others. This provides a defined legal status beyond the basic protection available to electronic signatures.
Neither status answers every contractual question. Signer authority, the agreement’s contents and any transaction-specific formalities still matter. Identity verification is also distinct from qualification: checking an account holder’s identity does not, by itself, turn a signature into a QES.
3. When to choose each
Consider SES for everyday agreements where the applicable rules and receiving organisation permit it. Routine acknowledgements or ordinary service agreements may be suitable examples, depending on their requirements. Review how you will demonstrate signing intent, identify the signer and connect the signing record to the final document.
Choose QES when the applicable rules or receiving organisation specifically require it, or when your process calls for its handwritten-signature equivalence under eIDAS. Confirm the qualified certificate, provider status and qualified signature creation device rather than relying on a product label.
A high contract value is a reason to examine the requirements carefully, not a universal rule that QES is mandatory. For cross-border agreements, establish the required signing form before invitations go out. This avoids discovering later that the chosen method does not meet the recipient’s requirements.
4. How this relates to WQ3
WQ3 is aligned with eIDAS and offers exactly three signing levels: electronic signature, remote signing and token signing. These product levels are not interchangeable with the eIDAS categories. Remote or token signing should not be assumed to be QES merely because of the method’s name or its use of a digital certificate.
WQ3 recommends electronic signature for everyday agreements, and remote or token signing for formal, high-value contracts and organisations requiring a certified digital certificate. Its eKYC account-verification add-on can be required with any level; it is not another signing level or proof of QES status.
Select the requirements for each signer before sending. After completion, retain the final file and completion certificate, and use WQ3’s public check page to review the fingerprint match, signer names, levels and timestamps. These records support review without changing the signature level used.
This article is general information, not legal advice.
Read more on the related WQ3 page