What is the difference between QES and AES?

An Advanced Electronic Signature (AES) under eIDAS Art. 26 identifies the signatory and detects document changes, but does not carry a statutory legal presumption equal to a handwritten signature. A QES requires a qualified certificate from an EUTL-listed QTSP and a qualified signature creation device, giving it the highest legal weight under EU and Swiss law.

When is a qualified electronic signature required by law?

In Switzerland, QES is required for contracts mandating written form, such as non-compete clauses in employment contracts (OR Art. 340) and personal guarantee agreements (OR Art. 493). In the EU, specific transaction types designated by member states require QES. For most commercial contracts, AES is sufficient, but QES provides the strongest legal protection.

Who issues qualified certificates for QES?

Qualified certificates are issued by Qualified Trust Service Providers (QTSPs) listed on the EU Trusted List at eidas.ec.europa.eu/efda/tl-browser/. In Switzerland, QTSPs must be accredited under ZertES by the Federal Office of Communications (BAKOM). Swisscom Trust Services is accredited under both ZertES and listed on the EUTL.

Does Swiss Trust Layer provide QES?

Yes. Swiss Trust Layer integrates with accredited QTSPs to apply qualified electronic signatures. Documents receive a qualified certificate chain, a trusted timestamp under RFC 3161, and a verification URL at validate.swisstrustlayer.com. Pricing starts at CHF 5 per document.

What Is a Qualified Electronic Signature (QES)?

Q: What is a qualified electronic signature?

A qualified electronic signature (QES) is an advanced electronic signature created with a qualified certificate from a Qualified Trust Service Provider (QTSP) listed on the EU Trusted List, using a qualified signature creation device. Under eIDAS Art. 25(2), a QES has the equivalent legal effect of a handwritten signature across all EU member states. Under ZertES Art. 11, a QES has the same legal effect as a handwritten signature in Switzerland.

A qualified electronic signature (QES) is the only e-signature type that carries the same legal weight as a handwritten signature under eIDAS Art. 25(2) and ZertES Art. 11. Here is what that means in practice.

An electronic signature is not a single thing. European and Swiss law define three distinct tiers, each with different legal weight and technical requirements. At the top sits the qualified electronic signature, or QES, the only tier that carries the same legal presumption as a handwritten signature by statute.

The Three Tiers of Electronic Signature

Under eIDAS Regulation (EU) No 910/2014 and Switzerland's ZertES (SR 943.03), electronic signatures are classified into three levels:

Simple Electronic Signature (SES) — any data in electronic form used to sign. A typed name in an email qualifies. No identity verification required. Legally the weakest tier.
Advanced Electronic Signature (AES) — uniquely linked to the signatory, capable of identifying them, created using data under their sole control, and linked to signed data so any change is detectable (eIDAS Art. 26). Strong but not qualified.
Qualified Electronic Signature (QES) — an AES created by a Qualified Electronic Signature Creation Device with a qualified certificate from a Qualified Trust Service Provider listed on the EU Trusted List. Under eIDAS Art. 25(2), a QES has the equivalent legal effect of a handwritten signature across all EU member states. Under ZertES Art. 11, a QES created in Switzerland has the same legal effect as a handwritten signature under Swiss law.

What Makes a Signature Qualified

The word qualified refers to the certificate used, not the software. A QES requires a qualified certificate from a QTSP listed on the EU Trusted List at eidas.ec.europa.eu/efda/tl-browser/ for EU-qualified signatures, or accredited under ZertES for Swiss-qualified signatures. Swisscom Trust Services is both EUTL-listed and ZertES-accredited.

The certificate must be issued after in-person or video-based identity verification against a government-issued ID. The signatory's identity is tied to a real person by an accredited authority, not just an email address.

Where QES Is Required by Law

Swiss law requires QES for specific contract types. A QES is the only e-signature accepted for contracts where statute requires written form, including employment contracts with non-compete clauses (OR Art. 340) and guarantee agreements (OR Art. 493). Without QES, these contracts may be voidable.

How Swiss Trust Layer Uses QES

Swiss Trust Layer integrates with accredited QTSPs to apply QES to documents sealed on the platform. Pricing starts at CHF 5 per document. See the fiduciary solutions page for workflow details.

QES vs a Notarized Document

For documents requiring notarial certification, a QES alone does not substitute. For documents requiring only written form (Schriftlichkeit), a QES under ZertES Art. 11 satisfies the requirement. Confirm with a licensed attorney in the relevant jurisdiction.