If someone in Spain owes you money under a contract and has not paid, or you have been accused of not fulfilling your side of a deal, Spanish law gives both sides a clear set of rules to work from. Here is what actually applies.
Under the Spanish Civil Code, a contract is not just a piece of paper. Article 1,089 says obligations can arise from the law itself, from contracts, from quasi-contracts, and from wrongful acts or negligence. Article 1091 goes further: once you sign a contract, its terms carry the force of law between you and the other party, and both sides must fulfil them as agreed.
Spanish contract law also respects freedom to agree your own terms (Articles 1254 and 1255), but that freedom has a limit. Article 1256 makes clear that the validity and fulfilment of a contract can never be left to the discretion of just one of the parties. In other words, one side cannot simply decide on its own whether or not to honor what was agreed.
Article 1258 adds an important detail: a contract becomes binding the moment both sides agree to it, not only for what was explicitly written down, but also for everything that naturally follows from good faith, common practice, and the law. Article 1278 confirms this binding nature applies regardless of the form the contract took, whether written, verbal, or otherwise.
What happens when payment is late
Article 1100 states that someone who owes a delivery or a service is considered in default from the moment the other party formally demands, in or out of court, that they fulfil the obligation. Article 1108 deals specifically with money debts: if the obligation is to pay a sum of money and the debtor is in default, compensation for the delay is normally the agreed interest rate, or if nothing was agreed, the legal interest rate.
These provisions are the backbone of most breach of contract cases involving unpaid amounts, and understanding them helps you know where you stand before a dispute goes further.
