A contract signed with a click, an “I accept” box or a signature drawn on a phone is as binding as one on paper. The type of electronic signature does not change that validity; it changes how easy it is to prove if the other party denies it. The eIDAS Regulation distinguishes three types of signature, and only one is equivalent to a handwritten signature. In this article I explain what they are, how they differ and which to use in each case.
Form does not determine validity
A contract is binding whatever the form in which it is made, provided there is consent and the conditions of validity are met (article 1278 of the Civil Code). Law 34/2002, on e-commerce, confirms this for the digital environment: contracts concluded by electronic means produce all their effects. An agreement by email, an order confirmed by messaging or a signature on a screen are as binding as one signed on paper.
The common mistake —and the argument of anyone wanting to wriggle out— is to treat “electronic signature” as if it were a single thing. It is not. Regulation (EU) 910/2014, known as eIDAS and directly applicable in Spain, distinguishes three levels.
The three types of electronic signature
The simple electronic signature is any electronic data used to sign: the name at the foot of an email, an “I accept” box, a stroke on a tablet. It is a signature, but on its own it does not prove who made it.
The advanced electronic signature requires more: it must be uniquely linked to the signatory, allow them to be identified, be created using means under their sole control, and be attached to the document so that any later alteration is detectable. This is the level of the cloud signing platforms worthy of the name, which record who signed, when and from where, and seal the file.
The qualified electronic signature is an advanced signature created with a qualified device and based on a qualified certificate issued by a recognised trust service provider. It is the one on the electronic ID card (DNI electrónico) and the FNMT certificates.
Which one equals a handwritten signature
Of the three, only the qualified signature is equivalent by law to a handwritten one. This is established by article 25 of eIDAS. A contract signed in this way by both parties is, as regards authorship, as firmly established as one on paper.
A “simple” signature is not a worthless one
The fact that the other two are not equivalent to a handwritten signature does not deprive them of value. That same article 25 prohibits denying legal effect or admissibility as evidence to a signature merely because it is electronic or is not qualified. A simple or advanced signature may be enough to conclude a contract. The difference lies in the evidence: if the other party denies the signature, you have to be able to prove that it is theirs and that the document has not been altered.
What decides a case: the evidence
When an electronic signature is challenged, the question is settled on the ground of evidence. Law 6/2020 governs the evidential value of these signatures and how they are verified when denied, generally by means of an expert report. Proving that a digital contract is authentic —that the signature is whose it claims to be, that the date is the one recorded, that no clause was altered afterwards— depends on the metadata, the time stamps, the platform logs and the integrity of the file. It is a matter of electronic evidence: a well-preserved document defends itself; one kept carelessly, even with a qualified signature, makes life hard for whoever relies on it. I deal with this in more detail in why electronic evidence decides cases.
Which signature to use, depending on what is at stake
The choice is proportional to the risk. For everyday, low-value operations, a simple or advanced signature on a reliable platform is sufficient and leaves a trail. For high-value or foreseeably contentious operations —a significant sale, the sale of a company— it is worth requiring a qualified signature, or at least an advanced one with a proper audit trail. In any case, keep the original electronic file, not a printout or a screenshot: the evidential value is in the file.
At the firm we review and draft contracts from civil law, and when the problem is proving the authenticity of a digital document we approach it from cybercrime and electronic evidence. If you have a contract signed electronically and want to know whether it will hold up, you can write to us from the contact page.
Frequently asked questions
Is a contract signed with an electronic signature valid?
Yes. A contract is binding whatever its form, provided there is consent and the conditions of validity (article 1278 of the Civil Code), and Law 34/2002 confirms this for electronic means. An electronic signature is a valid way of giving consent.
Which electronic signature equals a handwritten one?
The qualified signature. Article 25 of the eIDAS Regulation gives it the same legal effect as a handwritten signature. It is the one on the electronic ID card and the FNMT certificates.
I signed with a click or with my finger on the screen, is that valid?
It may be. Under the eIDAS non-discrimination principle, a signature is not denied effect for being electronic or not qualified. The problem is not validity; it is evidence: if the other party denies it, you have to be able to prove that the signature is theirs and that the document has not been altered.
If the other party says they did not sign, what happens?
The question is settled by an expert report. Law 6/2020 governs the evidential value of these signatures and their verification when challenged. It then becomes decisive to have kept the original file and its trail —metadata, time stamps, platform logs—, which is the ground of electronic evidence.