Signing a rental agreement, a job offer or a property deal without touching paper has become routine, yet the question of whether that click on a commercial platform carries the same weight as a pen stroke still trips people up. The short answer: almost any electronic signature is legally binding, but not all of them defend you equally if someone later claims they never signed. Understanding the distinction matters most in the contracts where money, housing or employment is on the line.
- Three tiers exist: eIDAS defines simple, advanced and qualified electronic signatures, each with different legal presumptions.
- Burden of proof shifts: Qualified signatures carry a legal presumption of integrity, while non-qualified ones leave you arguing over audit logs and IP addresses.
- Context decides: A click is fine for most day-to-day deals, but property deeds still require a notary and public document.
The legal foundation: form is almost never the obstacle
The starting point is Spain’s Civil Code, whose Article 1278 states that contracts bind “whatever the form in which they were celebrated,” provided they meet the essential conditions of validity. The Information Society Services Law reinforces this in Article 23, confirming that contracts concluded electronically produce all their effects and that, where the law demands something be in writing, an electronic medium satisfies that requirement.
So the useful question is not whether an online contract is valid. It is what you will be able to prove if the signature is challenged.
Regulation (EU) 910/2014, known as eIDAS and amended in 2024 by Regulation (EU) 2024/1183, sets out three escalating levels. A simple electronic signature covers data in electronic form attached to other data and used by the signer to sign — drawing your initials with a finger on a screen, typing your name or ticking an “I accept” box all qualify. An advanced electronic signature must meet four conditions under Article 26: it is uniquely linked to the signer, capable of identifying them, created using data the signer controls with a high level of confidence, and linked to the document so that any later change is detectable. A qualified electronic signature is an advanced signature created with a qualified signature creation device and based on a qualified certificate issued by a supervised trust service provider.
Article 25 lays down the two rules that matter. First, no legal effect or admissibility as evidence can be denied to a signature merely because it is electronic or not qualified. Second, a qualified signature has a legal effect equivalent to a handwritten signature.
Commercial platforms operate across all three tiers. DocuSign, for instance, states that its service supports simple, advanced and qualified electronic signatures. For the advanced level it adds identity verification of the signer, and for the qualified level it requires in-person or equivalent identity verification, which can be done by video conference. The default click-to-sign remains the simple tier.
What changes in court: who has to prove what
This is where the real difference between tiers lives, and it is fixed by Spain’s Law 6/2020, which complements the European regulation. Its Article 3 refers to two paragraphs of Article 326 of the Civil Procedure Law, which Law 6/2020 itself amended.
If a document was signed with a non-qualified trust service and the other party contests its authenticity, integrity or date, the general regime for proving private documents applies, without the presumption in favour of the document that a qualified service enjoys. In practice, that usually means disputing the platform’s audit trail, emails or IP addresses, and sometimes paying for an expert witness.
If a qualified service listed on the trusted list of qualified providers was used, the law presumes the document meets the contested characteristic and that the service worked properly. The party contesting it bears the burden of verification; if the check comes back negative, they pay their own costs, and if the court deems the challenge reckless it may impose a fine of 300 to 1,200 euros.
The practical reading: for everyday matters, the simple signature of a reputable platform is enough, and most contracts never reach a courtroom. But the signature level is a decision about who will carry the burden of proof if things go wrong, and that is best decided in advance. A rental with a deposit, an employment contract with non-compete clauses or the sale of a second-hand car are exactly the cases where someone may have an interest in denying their signature.
Rentals, jobs and purchases: when a click is enough
Housing rental. A lease signed through an electronic signature platform is valid. The Civil Code only requires a public document for property leases of six or more years when they must affect third parties (Article 1280). Before signing anything remotely, though, verify who the owner is: the usual fraud lies not in the signature but in the person.
Employment contract. This falls under the general principle of Article 23 of the Information Society Services Law: if the law requires written form, an electronic medium satisfies it. Keep a copy of the signed PDF with its audit report; it is your proof of the agreed terms.
Property purchase. Here a platform signature is not enough for everything. Article 1280 of the Civil Code requires a public document for acts that create, transfer or modify rights over real estate, and the Information Society Services Law itself excludes contracts that legally require public form or the involvement of notaries or registrars. A deposit agreement can be signed online; the deed must be executed before a notary.
When to use your digital certificate. If you hold an FNMT certificate or electronic DNI, you can sign a PDF with AutoFirma, the government application available for Windows, macOS and Linux, with a mobile client for Android and iOS. A signature based on a qualified certificate raises the evidential bar without paying a platform, although strict qualified signature status additionally requires a qualified signature creation device; if that is decisive in your case, ask whoever drafts the contract. Note also that Law 6/2020 caps the validity of qualified certificates at five years: once expired, they cannot be used to sign.
What is coming may simplify all of this. The reformed eIDAS requires European digital identity wallets (EUDI Wallet) to let any natural person sign by default and free of charge with a qualified electronic signature, though each member state may limit that free use to non-professional purposes.
The likely trajectory is that once the wallet is on everyone’s phone, simple platform signatures will be reserved for trivial matters and qualified signatures will become the norm for rentals and employment contracts. Until then, the practical rule is straightforward: sign online without fear, but choose the signature level with the worst day of the contractual relationship in mind, not the first.