Electronic Signatures
The three signature levels according to eIDAS, when which signature is sufficient, and why canvas signatures are legally valid for most freelance contracts.
Electronic signatures make it possible to sign contracts and proposals digitally – quickly, conveniently, and legally valid. This guide explains the different signature levels and when which signature is sufficient for your purposes.
The Three Signature Levels According to eIDAS
The EU regulation eIDAS defines three levels of electronic signatures with different security levels:
| Feature | Simple (SES) | Advanced (AES) | Qualified (QES) |
|---|---|---|---|
| Security level | Low | Medium | High |
| Identity verification | None | Limited (e.g., SMS code) | Strict (video ident) |
| Cryptography | Not required | Required | Certified required |
| Evidential value | Low | Medium | High (prima facie evidence) |
| Replaces written form | ❌ | ❌ | ✅ |
| Costs | Low/free | Moderate | Higher |
Simple Electronic Signature (SES)
The simplest form of electronic signature:
- Scanned signature
- Typed name
- Canvas signature (drawn with finger or stylus)
- Checkbox "I agree"
Legal effect: Generally recognized as declaration of intent, but lower evidential value in disputes.
Advanced Electronic Signature (AES)
Higher security level through:
- Unique assignment to the signer
- Identification of the signer (e.g., email + SMS code)
- Subsequent changes are detectable
- Cryptographic security
Legal effect: Increased evidential value, recommended for most business contracts.
Qualified Electronic Signature (QES)
The highest level with maximum legal certainty:
- Certificate from a qualified trust service provider
- Strict identity verification (video ident, PostIdent)
- Legally equivalent to handwritten signature
- Replaces the legal written form
Legal effect: Maximum evidential value, legally equivalent to handwritten signature.
When is Which Signature Sufficient?
The Principle of Freedom of Form
German civil law allows most contracts to be form-free – verbal, by email, or digital. The written form (§ 126 BGB) is only legally required in certain cases.
Form-Free Contracts (SES/AES Sufficient)
For most freelance contracts, a simple or advanced signature is sufficient:
| Contract Type | Recommended Signature |
|---|---|
| Work contracts (§ 631 BGB) – Projects, design, development | SES or AES |
| Service contracts (§ 611 BGB) – Consulting, coaching | SES or AES |
| Proposals and order confirmations | SES with audit trail |
| Freelance framework agreements | AES |
| T&Cs and terms of use | SES (checkbox) |
Written Form Required (QES Necessary)
In these cases, a qualified electronic signature is required or written form is completely excluded:
| Document | Requirement |
|---|---|
| Fixed-term employment contracts | QES or handwritten |
| Post-contractual non-compete clauses | QES or handwritten |
| Employment law terminations | Handwritten only (§ 623 BGB) |
| Sureties (except commercial) | QES or handwritten |
| Debt acknowledgments | QES or handwritten |
Important: For employment law terminations, electronic form is excluded – a handwritten signature is always required.
Canvas Signatures: Legally Sufficient?
A common question: Are signatures drawn with a finger or stylus legally valid?
Yes, for form-free contracts, canvas signatures are legally valid
Canvas signatures are considered simple electronic signatures (SES) and are therefore perfectly sufficient for most freelance contracts.
Document for Increased Evidential Value
To increase the evidential value of a canvas signature, you should store the following information:
- Timestamp – Date and time of signing
- Name and email of the signer
- IP address
- Signature graphic – The actually drawn signature
- Browser and device information
- Hash value of the document – Proof that the document was not modified
This "audit trail" significantly increases evidential value and makes the signature practically as secure as an AES.
Recommendations for Proposal Air
| Document Type | Recommended Signature |
|---|---|
| Proposal (< 5,000 €) | SES with audit trail |
| Proposal (> 5,000 €) | AES |
| Work contract | AES |
| NDA/Confidentiality agreement | AES or QES |
| Data processing agreement (DPA under GDPR) | AES or QES |
How to Use Signatures in Proposal Air
- Activate signature – Enable the signature function for your proposal
- Send link – Your customer receives a link to sign
- Capture signature – The customer signs via canvas or typed signature
- Audit trail created – All relevant data is automatically saved
- PDF generated – A signed PDF with all evidence is created
International Recognition
The eIDAS regulation applies in all EU member states. Qualified electronic signatures from one EU country are recognized in all other EU countries.
For Non-EU Countries
| Country | Recognition |
|---|---|
| Switzerland | Own ZertES law, largely compatible |
| USA | E-SIGN Act and UETA, more liberal than EU |
| UK | Own regulation after Brexit, but largely compatible |
For international contracts, a qualified electronic signature or agreeing to written form in the contract itself is recommended in case of doubt.
Frequently Asked Questions
Is an Email Confirmation Sufficient?
Yes, for form-free contracts, an email confirmation ("I hereby commission...") can also serve as a declaration of intent. However, the evidential value is lower than with a canvas signature with audit trail.
What Happens with Signature Forgery?
For disputed signatures, the burden of proof varies:
- SES/AES: The sender must prove authenticity
- QES: The recipient must prove forgery (prima facie evidence)
Do I Need an External Signature Service?
Not necessarily. For SES and AES, you can use your own solutions. For QES, you need a qualified trust service provider (e.g., D-Trust, sign-me, Swisscom).
Related Topics
- Best Practices – Designing proposals professionally
- GDPR – Data protection in digital contract signing
- Conversion Tips – Digital signatures for faster closes
Billing and Invoicing
Create professional invoices from accepted proposals, send them electronically as PDF or ZUGFeRD e-invoices, and manage your complete invoice history with status tracking and audit trail.
GDPR for Proposals and Customer Data
Which customer data you may store, retention periods, and the appropriate legal bases for your data processing.