Short answer. Generally, you bear the loss. Article 2070 of the Civil Code says that when a guarantor pays without notifying the debtor, and the debtor unknowingly pays again, the guarantor has no remedy against the debtor — only against the now-insolvent creditor. There is a narrow exception for gratuitous guarantors prevented by a fortuitous event.
What the law says
If the guarantor has paid without notifying the debtor, and the latter not being aware of the payment, repeats the payment, the former has no remedy whatever against the debtor, but only against the creditor.
Civil Code, Article 2070 — Double Payment. Read the full provision →
The general rule: no notice, no remedy against the debtor
Article 2070 of the Civil Code places the risk squarely on the guarantor who paid in silence. When you settle the debt without telling the borrower, and the borrower — unaware of what you did — goes ahead and pays the creditor as well, the law says you have no remedy whatever against the debtor. The debtor did exactly what they were supposed to do: pay the creditor. You failed to communicate your prior payment, so you cannot turn around and demand that the debtor now reimburse you. Your only recourse is against the creditor who collected twice.
Why the notice requirement exists
The rule reflects a basic fairness principle. The debtor had an obligation to pay the creditor. If you as guarantor paid first but kept silent, the debtor had no way of knowing the debt was already settled. Imposing a loss on an innocent debtor who paid in good faith would be unjust. The law shifts the consequences of that failure to communicate onto the person who caused it — the guarantor who chose to pay without notifying anyone. The duty to notify is simple and easy to satisfy; the consequences of ignoring it are significant.
The exception for gratuitous guarantors stopped by a fortuitous event
Article 2070 carves out one narrow exception. If your guaranty was gratuitous — meaning you received nothing for it — and you were prevented by a fortuitous event from notifying the debtor before they made a second payment, and the creditor then becomes insolvent, the law shifts. In that limited scenario, the debtor must reimburse you for what you paid. A fortuitous event means something beyond your control — not mere inconvenience or oversight. This exception does not apply if you simply forgot to notify, or chose not to.
What this means for your situation
If your guaranty was not gratuitous — meaning you received compensation for being the guarantor — the exception does not apply to you, and you are left with only a claim against the insolvent creditor. If your guaranty was gratuitous and you genuinely were prevented by circumstances outside your control from giving notice, you may have a claim against the debtor under the exception. Either way, gathering evidence about the nature of your guaranty, the sequence of payments, and why notice was not given will be essential. A lawyer can assess whether the exception applies to your specific facts.