How much can be claimed on an invoice paid late
The statutory late payment interest rate for commercial transactions in Spain is 10.40% for the second half of 2026. It is not a penalty that has to be agreed: it applies by law from the day after the due date, even when the contract says nothing. Here is where it comes from, how to calculate it, and when claiming it is worth the trouble.
What it is, exactly
The Resolution of 30 June 2026 of the Spanish Treasury sets the rate at 10.40% for the second calendar half of 2026. For the first half it was 10.15%.
The arithmetic holds no mystery and sits in article 7 of Law 3/2004 on combating late payment: take the interest rate applied by the European Central Bank to its most recent main refinancing operation of the previous half-year, and add 8 percentage points. The ECB applied 2.40% on 30 June 2026. 2.40 plus 8 is 10.40.
The Treasury publishes the rate once per half-year. The one that governs a debt is the one in force in the half-year it accrues, so an invoice dragging since March carries two stretches: 10.15% until 30 June and 10.40% from 1 July.
What many people do not know they can add
Article 8 of the same law gives the right to a fixed compensation of 40 euros for recovery costs on every invoice claimed, with nothing to justify. Forty euros per invoice, not per customer. On a ledger with many small invoices that figure weighs more than the interest.
And where the real cost of the recovery exceeds those 40 euros, it can be claimed on top, this time with evidence.
A worked example
An invoice of 12,000 euros, due on 1 August 2026, paid on 15 September. That is 45 days late, all inside the second half-year.
| Item | Calculation | Amount |
|---|---|---|
| Late payment interest | 12,000 × 10.40% × 45 / 365 | 153.86 € |
| Recovery cost compensation | Article 8, fixed amount | 40.00 € |
| Total claimable | 193.86 € |
On a single invoice it looks small. Multiply it by the invoices that run late over a year and it stops looking small. That is exactly the conversation to have before deciding whether to claim.
The calculation when a debt crosses half-years
An invoice due on 15 May and paid on 30 September does not carry a single rate. It splits:
- 16 May to 30 June, 46 days at 10.15%
- 1 July to 30 September, 92 days at 10.40%
Adding up the days and applying the latest rate to all of them is the most common error, and it always favours whoever is claiming, which is precisely what makes it a problem when the figure has to be defended.
Is it worth claiming?
The honest answer is that it depends, and it depends on two things that do not appear in the calculator.
When it is
- When the delay is systematic. A customer paying at 90 days what was agreed at 30 does not have a cash problem, they have a habit. Interest is the only signal that reaches the right department.
- When the relationship is already broken. If the debt is heading for court, the interest and the 40 euros go into the account from the start or they do not go in at all.
- When it is used as leverage, not as punishment. Announcing the interest calculation and offering to waive it in exchange for payment today works more often than collecting it.
When it is not
- When the amount does not pay for the work. If calculating and chasing 30 euros of interest costs two hours of somebody's time, the argument was won and the money was lost.
- When the customer is worth more than the debt. That is not a reason to skip the principal, it is a reason to choose a different tool.
- When it has never been mentioned. Claiming interest out of nowhere after three years of tolerated delays reads as aggression, not as applying the law.
That last one matters most and is skipped most. The right exists from the due date, but the credibility is built earlier: in the terms of sale, in the first invoice and in the first delay.
What cannot be agreed away
Law 3/2004 declares void any clause that is abusive on the payment term, the interest rate or the recovery cost compensation. Specifically, the general term is 30 days and it can only be extended to 60 by express agreement, and that agreement cannot be the product of a dominant position.
Put plainly: a supplier may accept 60 days, but a standard term imposing 120 does not become valid because it was signed.
Frequently asked questions
What is the late payment interest rate in Spain in 2026?
10.40% for the second half and 10.15% for the first. The Treasury publishes it every six months, and it comes from adding 8 points to the ECB rate, which was 2.40% on 30 June 2026.
Does it have to be in the contract to be claimable?
No. It accrues automatically from the day after the due date, with no notice and no prior claim needed, and regardless of what the contract says. What a contract can do is agree a higher rate.
Is commercial late payment interest the same as the statutory interest on money?
No, and confusing them is expensive. The statutory interest on money is far lower and applies to other situations. Between businesses, on commercial transactions, this is the one that applies.
Can the 40 euros be claimed on every invoice?
On every invoice claimed for non-payment, with no expense to prove. It is 40 euros per invoice, not per customer or per grouped claim.
From which day does interest run?
From the day after the agreed due date. Where no term was agreed, from 30 calendar days after delivery or after receipt of the invoice, depending on the case.
And if the customer is a public authority?
That regime has its own particularities on terms and on how to claim, although the reference interest rate is the same. It deserves a separate review before applying the above as written.
What comes next
Interest is what gets charged once it is already late. The cheap part happens earlier: spotting in time a customer who is about to stop paying and measuring DSO to know what a day of delay costs. And when it is time to chase, do it with the right letter for the moment, which is not the same on day 10 as on day 60.
Calculating interest invoice by invoice, by hand, is exactly the kind of task nobody does. In FK it comes out of the due date itself. Book a demo and see it against real data.