Knowledge

6 May 2026

ZertES: a practical guide to legally compliant electronic signatures in Switzerland

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Introduction

Electronic signatures are now a standard part of digital workflows. In Switzerland, however, their legal validity is governed by a specific framework: ZertES (Bundesgesetz über die elektronische Signatur / Loi fédérale sur la signature électronique / Legge federale sulla firma elettronica).

For companies operating in Switzerland, understanding ZertES is essential to ensure that digitally signed documents are not only convenient, but legally enforceable.

What is ZertES?

ZertES is the Swiss federal law regulating electronic signatures and trust service providers. Its purpose is to establish legal certainty in digital transactions by defining how identities are verified and how signatures are issued.

Unlike more flexible international approaches, ZertES places strong emphasis on certified identity verification and regulated infrastructure.

Legal validity under Swiss law

Under Swiss law, only a Qualified Electronic Signature (QES) is legally equivalent to a handwritten signature when written form is required (Art. 14 para. 2bis CO).

This distinction is critical in practice. While many digital signatures are sufficient for internal or low-risk agreements, they do not fulfil statutory form requirements.

Typical use cases where QES is required include:

financial agreements
termination of a tenancy agreement
regulated or compliance-driven processes

When is a ZertES (QES) signature required?

A Qualified Electronic Signature (QES) under ZertES is required whenever a document is subject to written form requirements under Swiss law.

This typically applies when:

the contract is governed by Swiss law, or
the document must comply with Swiss legal or regulatory requirements

In these cases, the validity of the signature depends on whether it fulfils the formal requirements defined by Swiss law, not on where a potential dispute would be resolved.

Typical examples include cases where written form is legally required, such as the termination of a tenancy agreement, consumer credit agreements, assignments of claims, and documents in regulated industries.

When written form is required under Swiss law, only a QES issued within a ZertES-compliant framework is legally equivalent to a handwritten signature.

ZertES in an international context

ZertES is often compared to the European eIDAS framework, as both define levels of electronic signatures and recognise qualified signatures as legally equivalent to handwritten ones.

However, they operate in different legal systems. While eIDAS ensures mutual recognition across EU member states, its validity in Switzerland is not automatic.

For organisations operating across borders, this distinction is essential: a signature compliant with eIDAS does not necessarily fulfil Swiss legal requirements under ZertES.

Types of electronic signatures

ZertES definiert drei Stufen elektronischer Signaturen.

A Simple Electronic Signature (SES) is the most basic form, commonly used for convenience.
An Advanced Electronic Signature (AES) offers stronger integrity and identity linkage.
Only the Qualified Electronic Signature (QES) combines verified identity, certified issuance, and legal equivalence to handwritten signatures.

Why many solutions are not compliant in Switzerland

A common misconception is that any e-signature platform can be used for legally binding agreements. In reality, many widely used tools only provide simple or advanced electronic signatures.

Under Swiss law, legal validity in cases requiring written form does not depend on the signature interface alone. It depends on whether the entire signing process is built on a ZertES-compliant framework, including certified identity verification, qualified certificates, and the involvement of recognised trust service infrastructure.

Without this, a solution may support digital signing, but it does not meet the legal standard required for a Qualified Electronic Signature (QES) in Switzerland.

Solution	QES (ZertES) support	Legal validity in Switzerland	Notes
DeepSign	Yes Native	Yes Equivalent to handwritten	End-to-end ZertES workflows, includes free ID verification
Skribble	Yes	Yes Equivalent to handwritten	Supports SES/AES/QES with 3rd party, paid ID verification options
Swisscom Sign	Yes	Yes Equivalent to handwritten	End-to-end ZertES workflows, with paid ID verification
SwissSign	Yes	Yes Equivalent to handwritten	Official Trust Service Provider certified under ZertES
DocuSign	Conditional Conditional	Conditional Depends on setup	QES possible only via integration with QTSPs (e.g. Swisscom)
Adobe Acrobat Sign	Conditional Conditional	Conditional Depends on setup	QES possible only via integration with QTSPs (e.g. Swisscom)
YouSign	No	Conditional Limited / Low	Native QES is strictly eIDAS (EU). Invalid for Swiss written form (ZertES).
Dropbox Sign	No	Conditional Limited / Low	Only supports eIDAS QES. No documented support for ZertES requirements.
PandaDoc	No	Conditional Limited / Low	No native support for qualified signatures in Switzerland (ZertES)
Odoo Sign	No	No Not for QES	SES/AES support only. No infrastructure for ZertES-compliant qualified signatures.

How to implement compliant signing

A ZertES-compliant process requires identity verification, qualified certificate issuance, secure signing, and timestamping. These elements ensure authenticity, integrity, and legal enforceability.

Conclusion

ZertES defines one of the most rigorous frameworks for electronic signatures in Europe. For Swiss businesses and public organisations, adopting a compliant solution is not only a legal requirement, but a foundation for trusted digital workflows.

FAQs

Is ZertES mandatory in Switzerland?

ZertES itself is not mandatory in all cases. However, whenever Swiss law requires a document to be in written form, a Qualified Electronic Signature (QES) issued within a ZertES-compliant framework is required.

When do I need a Qualified Electronic Signature (QES)?

A QES is required when a document must fulfil statutory written form requirements under Swiss law. Typical examples include the termination of a tenancy agreement, certain financial contracts such as consumer credit agreements and assignments of claims, as well as other documents where written form is explicitly required by law.

Are simple electronic signatures legally valid in Switzerland?

Yes, simple electronic signatures (SES) can be legally valid for many use cases. However, they do not meet written form requirements and are not equivalent to handwritten signatures.

Is a QES under eIDAS valid in Switzerland?

Not automatically. While eIDAS and ZertES share similar principles, they are separate legal frameworks, and additional requirements may apply under Swiss law.