Signing PDFs: What Counts Legally?

A PDF lands in your inbox, and you're asked to sign it and send it back. Print, sign, scan it again? There's an easier way: draw your signature on screen and place it straight into the document. But does that actually hold up legally? The short answer: usually yes – but not always. In this article we explain the difference between a placed image signature and electronic signatures under the EU's eIDAS regulation, and which option fits which situation. One thing up front: this is general information, not legal advice. When in doubt, ask a lawyer.

What Technically Happens When You "Sign" a PDF

Draw a signature in our signature tool, the PDF viewer, the Clip PDF app or almost any other PDF app, and technically one thing happens: your signature is embedded into the PDF page as an image. Just like a photo or a logo. There is no certificate, no cryptography and no checksum involved. The document looks signed – but there is no technical proof of who placed the image or whether the PDF was modified afterwards.

That sounds like a flaw, but for many everyday cases it's perfectly fine – what matters is knowing the difference.

The Three Levels of the eIDAS Regulation

Since 2016, the EU's eIDAS regulation has defined which electronic signatures exist and what they mean legally, across all member states. It distinguishes three levels:

1. Simple Electronic Signature (SES)

Anything electronic that expresses an intent to sign: the placed image signature, a typed name under an email, a clicked "I agree". Worth knowing: under Article 25 of eIDAS, an electronic signature cannot be denied legal effect solely because it is electronic. So an SES isn't "invalid" – it just carries little evidential weight, because an image is easy to copy.

2. Advanced Electronic Signature (AES)

An AES is uniquely linked to one person, created with means only that person controls, and makes any later change to the document detectable. Technically this usually relies on a cryptographic certificate. Providers such as DocuSign, Adobe Acrobat Sign, Skribble or Yousign create these; when you open such a PDF, the reader shows whether the signature is intact.

3. Qualified Electronic Signature (QES)

The highest level: an AES that additionally rests on a qualified certificate from an audited trust service provider – issued after verifying your identity, for example via ID card or video identification. Only the QES is legally equivalent to a handwritten signature: in Germany, for instance, it satisfies the statutory written-form requirement under section 126a of the Civil Code, unless the law explicitly rules out electronic form. Other countries follow similar logic, such as the US ESIGN Act.

When Is the Image Signature Enough in Practice?

Here's the good news: most contracts and declarations are not subject to any form requirement. They don't need a signature at all to be valid – a verbal "yes" or an email is legally sufficient. The signature then mainly serves documentation and courtesy. For those cases, a placed image signature is entirely adequate, for example:

• Internal approvals – leave requests, acceptance reports, purchase sign-offs
• Quotes and order confirmations between business partners who know each other
• Delivery notes, timesheets, meeting minutes
• Everyday consent forms – the reply slip for school, the club registration

To be honest, though: the evidential value is low. Anyone disputing their signature can point out that any image can be pasted in. So if serious money is involved, you don't know the other party, or a dispute seems likely, choose an AES or QES – even where no written form is required by law.

When Do You Definitely Need More?

For some documents the law prescribes written form. Then only a handwritten signature on paper will do – or a QES, where electronic form is permitted. In some cases electronic form is even explicitly excluded. Well-known examples from German law:

• Terminating an employment contract and mutual termination agreements (section 623 Civil Code): written form, electronic form excluded – even a QES won't help here, it has to be paper.
• Personal guarantee declarations (section 766 Civil Code): paper as well.
• Real estate purchases, inheritance contracts: notarization required – nothing works without a notary, and certainly not electronically.
• Consumer loan agreements and several other contracts with statutory form requirements.

And here we'll be blunt: for these cases, Clip PDF and our signature tool are the wrong instrument. A placed image signature does not satisfy written-form requirements. If you need a QES, go through a qualified trust service provider – for example sign-me by D-Trust (Bundesdruckerei), Skribble, or DocuSign with its QES option. These providers verify your identity once and then issue the qualified certificate – for form-bound contracts there is no way around it.

Step by Step: Signing a PDF for the Everyday Case

For all form-free cases, it works like this – right in your browser, no registration:

1. Open the signature tool and load your PDF – the file stays on your device and is processed locally in the browser.
2. Draw your signature with mouse, finger or stylus; it is stored locally so you can reuse it next time.
3. Pick the page, place the signature and adjust its size.
4. Download the finished PDF and send it off.

Alternatively, the same works in the PDF viewer or on the go in the Clip PDF app. In fairness: if you own a Mac, the built-in Preview app can do the same thing – for Apple users with no further needs, that's the simplest option. Our tool earns its place when you work across platforms or want signing alongside other features such as merging or compressing.

Improving Evidential Value in Everyday Use

A few simple habits make your image signature more credible if things are ever disputed:

• Send the signed PDF from your known email address and keep the email thread – it documents sender and time.
• Add place and date next to the signature.
• Keep the original file you sent.
• Optionally, password-protect the PDF against editing with our protection tool – not tamper-proof evidence, but it discourages casual changes.

Frequently Asked Questions (FAQ)

Is a placed image signature legally valid?

For contracts without form requirements: yes, it can take legal effect and cannot be rejected merely for being electronic. It proves little, however – for important contracts an AES or QES is the safer choice.

Is a scanned signature the same as a QES?

No. A scan is just an image and therefore a simple electronic signature. A QES rests on a qualified certificate with identity verification and is equivalent to a handwritten signature.

Do invoices need to be signed?

No. In Germany and most other countries, invoices are valid without any signature – on paper or as a PDF.

Can you tell whether a PDF was changed after signing?

With an image signature: no. Only AES and QES seal the document cryptographically, so the PDF reader flags any later modification.

How do I get a qualified signature?

Through a qualified trust service provider on the EU trust list, e.g. D-Trust (sign-me) or Skribble. After a one-time identification – via electronic ID or video identification, for example – you can sign at the qualified level there.