Short answer. Binding, but harder to prove. Article 1156 defines an obligation as a juridical necessity to give, to do or not to do, and Article 1356 makes contracts obligatory in whatever form they were entered into. Writing is about evidence and, for a few contracts, enforceability — not about existence.

What the law says

An obligation is a juridical necessity to give, to do or not to do.

Civil Code, Article 1156 — Definition of an Obligation. Read the full provision →

Form is not the source of the obligation

Article 1156 is as short as a rule gets: An obligation is a juridical necessity to give, to do or not to do. Nothing in it mentions paper. Article 1157 lists where obligations come from — law, contracts, quasi-contracts, acts or omissions punished by law, and quasi-delicts — and Article 1305 describes a contract as a meeting of minds. Article 1315 completes the picture: contracts are perfected by mere consent. A verbal loan is therefore a real obligation from the moment the money changed hands, and Article 1159 gives it the force of law between the parties.

The exceptions that do require form

Article 1356 states the rule and its limit in one breath: contracts are obligatory in whatever form they may have been entered into, provided the essential requisites for their validity are present; but where the law requires a form for validity or enforceability, or requires that a contract be proved in a certain way, that requirement is absolute and indispensable. A plain loan of money between friends is not in that category. Some undertakings are — notably a promise to answer for another person's debt, which the Statute of Frauds requires to be in writing before it can be enforced. So the question is always which kind of promise you are dealing with.

The real cost of not writing it down

Two things bite. The first is proof: without a document you are proving the loan by messages, transfers, witnesses and the borrower's own admissions, and a defendant who simply denies receiving anything shifts the whole burden onto you. The second is time. Article 1145 requires an action upon an oral contract to be commenced within six years, against the ten years Article 1144 allows for a written one. Four years is a large penalty for a handshake, and it runs from when the right of action accrues, not from when you decide the friendship is over.

Turn the promise into a record

You do not need a new contract; you need an acknowledgment of the existing one. A dated message in which the borrower confirms the amount and says when he will pay is worth more than a formal document nobody signs, and Article 1155 treats a written acknowledgment of the debt by the debtor as interrupting prescription. Keep the transfer slips and the conversation in which the loan was agreed. If the promise concerns interest, note that it must be expressly stipulated in writing before any is due — a verbal rate collects nothing, however clearly it was said.

Cases citing this provision

These Supreme Court decisions cite the provision above. We list them so you can read them yourself; the summaries of what each decided are not ours to give.

Related provisions

Note. Statute text quoted on this page is reproduced from the official enactment and is linked to the full provision. The explanation around it is general legal information from Vivas & Nobles Law Office, not legal advice. Whether it applies to your situation depends on facts only a lawyer reviewing them can assess.