How to claim an unpaid invoice in Spain

Between businesses in Spain, Ley 3/2004 sets a 30-calendar-day payment term from delivery when none was agreed (art. 4.1), and no agreement can push it beyond 60 calendar days (art. 4.3). Once the term expires the debtor is automatically in default, with no notice needed (art. 5), and owes:

• the agreed late-payment interest or, failing that, the legal rate: ECB rate + 8 points (art. 7);
• a fixed 40€ recovery-cost compensation, added without having to ask (art. 8.1).

The rate for each semester and a worked example are in the late-payment interest guide.

A short, polite email with the invoice number, amount, due date and how to pay. If there is no reply, repeat every few days with a gradually firmer tone, and keep every message: it is your record of having claimed.

If reminders do not work, the usual next step is a formal demand stating:

• the invoice details (number, date, amount and due date);
• the accrued late-payment interest and the 40€ under arts. 7 and 8 of Ley 3/2004;
• a specific deadline to pay and a proposal to settle without going to court.

What matters is being able to prove the debtor received it, when, and with what content. Correos' burofax lets you certify the text sent and get a receipt signed by the recipient (Correos).

Since 3 April 2025, Organic Law 1/2025 generally requires an attempt to negotiate before suing in the civil courts, including the special proceedings in book IV of the Civil Procedure Act, where the monitorio sits (art. 5); the monitorio is not among the exceptions in its art. 5.2. Failing a document signed by both parties, the attempt can be evidenced by any document proving the other party received the invitation to negotiate or the proposal, on what date, and could access its full content (art. 10.2). A demand with a proposal sent by a provable channel leaves that record. If you are unsure how it applies to your case, ask a lawyer.

The monitorio is the court procedure designed to collect documented money debts. It is governed by arts. 812 to 818 of the Civil Procedure Act (LEC):

• What can be claimed. A money debt of any amount that is liquid, determined, due and payable, backed by documents — including invoices or delivery notes created by the creditor itself, if they are the kind that usually document that relationship (art. 812).
• Where. The first-instance court of the debtor's domicile or residence — since Organic Law 1/2025, the civil section of the Tribunal de Instancia (art. 813).
• How. A petition naming the debtor, the addresses, and the origin and amount of the debt, with the documents attached. It can use a standard form, on paper or from the courts' e-office, and needs neither a lawyer nor a court representative (arts. 814, 23.2 and 31.2).
• Payment order. The court requires the debtor to pay within 20 days or oppose, explaining why the amount is not owed (art. 815).
• If the debtor pays, the case is closed (art. 817). If it neither pays nor opposes, the monitorio ends and the creditor can request enforcement with a simple application (art. 816).
• If it opposes, the matter goes to trial (art. 818). Up to 15,000€ it continues as a juicio verbal (arts. 818.2 and 250.2); above that, the creditor has one month to file a claim, failing which the proceedings are discontinued with costs against the creditor. A lawyer and court representative may then be required depending on the amount: they are not mandatory in a juicio verbal of up to 2,000€ (arts. 23.2 and 31.2).

InvoiceUp helps with steps 1 and 2 by email: it sends reminders on the cadence you choose and, when you decide, a formal payment demand with the late-payment interest and the 40€, on invoices you already issued in your own invoicing tool. That demand sets a payment deadline, but it does not include a negotiation proposal and does not on its own evidence the negotiation attempt Organic Law 1/2025 requires before a monitorio. It does not send burofax, does not file the monitorio and is not a substitute for a lawyer.