How legally valid is an acknowledgement of debt?

Question

José Manuel Alburquerque · Accepted Answer

It is valid even if it is signed in a private document without a notary and even if it does not say where the debt comes from. Its main effect is that it is not the creditor who has to prove the debt but the debtor who has to prove that it does not exist or is not valid if they want to avoid paying it. It also interrupts the limitation period, so the time limit for claiming starts again in full. What it does not do is create a debt that did not exist. If it is not signed before a notary, it does not allow the creditor to apply directly for attachment of the debtor's assets either. Why it is valid and what effect it has An acknowledgement of debt is a document in which one person states that they owe a sum to another. The “Código Civil de Cataluña”, the Catalan Civil Code, has no rules of its own on it, so the Spanish Civil Code (“Código civil”) applies, which does not require any special form. A document signed by the debtor is enough. Under the Spanish Civil Code, even if a contract does not state its cause (consideration), that is, the reason why someone takes on the obligation, the cause is presumed to exist and to be lawful unless the debtor proves otherwise. The “Tribunal Supremo”, Spain's Supreme Court, explains it as follows. The acknowledgement does not create a new debt, nor is it binding on its own if there is no real debt behind it, but it changes who has to prove what. The creditor does not have to show where the sum claimed comes from. It is the debtor who, to escape liability, has to prove that the debt does not exist, that they have already paid it or that it is void, for example because the document was signed to conceal something else. What it should say Although it is not compulsory, the document should include: The names and identity document numbers of both parties. The amount and where the debt comes from, for example a loan made on a specific date. That avoids arguments about what is being acknowledged. How and when it will be paid, if a payment schedule has been agreed. The date and the debtor's signature. The creditor should keep the original. Limitation and collecting the debt Signing an acknowledgement interrupts the limitation period, after which the right to claim is lost if it has not been exercised in time. The time limit starts again from the beginning, with the ten years generally allowed by the Catalan code or the five under the Spanish Civil Code in most of the rest of Spain. If it is signed when the debt was already time-barred, its effects depend on the case and on what the document says. When it comes to collecting the debt, how it was signed matters: If it is a private document and the debtor does not pay, you have to claim in court, after first trying to reach an agreement as the law has generally required since 2025. There the document helps a great deal, because it is the debtor who has to prove that they owe nothing. If it is signed before a notary, as a public deed, the enforceable copy obtained from the notary allows the creditor to apply directly to the court for attachment of the debtor's assets, without prior court proceedings, if the debt exceeds 300 euros. The same applies to a commercial contract witnessed by a notary (a “póliza intervenida”).