Can you sign a contract via WhatsApp?

Yes, a contract can be concluded via WhatsApp, even if there is no signature in the usual sense. There is a contract when one party makes an offer and the other clearly accepts its main terms, such as the thing or service and the price. The law gives contracts concluded by electronic means the same effect as any other contract. On the other hand, contracts that require a deed before a notary, such as the gift of a flat or the creation of a mortgage, cannot be made this way. Messages are valid as evidence, but if the agreement is important it is advisable to keep them safely and sign a document afterwards.

José Manuel Alburquerque

Alburquerque Abogados

Property and contract law

When there is a contract

In Catalonia, as in most of the rest of Spain, the Spanish Civil Code (“Código civil”) applies, together with the national law on information society services, which regulates contracting by electronic means. Under that law:

  • Contracts concluded electronically have full effect if there is consent and the other requirements for validity are met.
  • The parties do not need to have agreed beforehand that they would use electronic means.
  • If the law requires a contract to be in writing, the electronic format satisfies that requirement.
  • The electronic record of the contract is admissible in court as documentary evidence.

Between people who are not in the same place, the contract is concluded when the person who made the offer learns of the acceptance or, if it has been sent to them, can no longer ignore it without acting in bad faith. Acceptance must be clear and relate to the main terms. An “OK” or an emoji is open to dispute. It is better to state in words what is being accepted, for example “I accept the price of 1.500 euros and that it starts on Monday”.

What cannot be done via WhatsApp

The rules on electronic contracting do not apply to family law and inheritance contracts. Nor do they apply to acts that the law requires to be carried out by public deed or before a notary, a registrar or a judge. That is why you cannot give away a flat, create a mortgage or make a succession agreement by message.

If what is sent via WhatsApp is a photo of a contract signed on paper or a document with an electronic signature, that also works, because a contract is valid by virtue of the agreement and not of the means by which it is sent.

How to protect yourself

  • Check that the number belongs to the other party and that the person writing has the authority to commit to the agreement, for example if they are acting on behalf of a company.
  • Messages can be deleted or edited and screenshots can be tampered with. Export the full conversation and keep the phone.
  • If you submit the messages and the other party denies that they are genuine, you will have to prove it, for example with an expert report or a notarial record (“acta notarial”) of the phone's contents.
  • If the agreement is important, sign it afterwards in a document, either on paper or with a reliable electronic signature.

This answer is provided for educational purposes and offers initial guidance on the question raised. Every matter has its own circumstances and nuances that require individual assessment. For that reason, before taking decisions with significant consequences, it is advisable to consult a professional and not to rely solely on this information. Personalised advice makes it possible to apply these explanations to the specific case and to assess the options available with greater certainty.